U.S. patent application number 13/051237 was filed with the patent office on 2011-12-15 for nmda receptor modulators and uses thereof.
Invention is credited to Amin Khan, Joseph Moskal, Paul Wood.
Application Number | 20110306586 13/051237 |
Document ID | / |
Family ID | 42039880 |
Filed Date | 2011-12-15 |
United States Patent
Application |
20110306586 |
Kind Code |
A1 |
Khan; Amin ; et al. |
December 15, 2011 |
NMDA Receptor Modulators and Uses Thereof
Abstract
Disclosed are compounds having enhanced potency in the
modulation of NMDA receptor activity. Such compounds are
contemplated for use in the treatment of diseases and disorder such
as learning, cognitive activities, and analgesia, particularly in
alleviating and/or reducing neuropathic pain. Orally available
formulations and other pharmaceutically acceptable delivery forms
of the compounds, including intravenous formulations, are also
disclosed.
Inventors: |
Khan; Amin; (Chicago,
IL) ; Wood; Paul; (Saskatoon, CA) ; Moskal;
Joseph; (Evanston, IL) |
Family ID: |
42039880 |
Appl. No.: |
13/051237 |
Filed: |
March 18, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/US2009/057401 |
Sep 18, 2009 |
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13051237 |
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61098088 |
Sep 18, 2008 |
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Current U.S.
Class: |
514/210.02 ;
540/363 |
Current CPC
Class: |
C07D 471/20 20130101;
A61P 25/28 20180101; A61P 25/24 20180101; A61P 25/30 20180101; A61P
25/00 20180101; A61P 25/32 20180101; A61P 25/18 20180101; A61P
25/04 20180101; C07D 487/10 20130101 |
Class at
Publication: |
514/210.02 ;
540/363 |
International
Class: |
A61K 31/407 20060101
A61K031/407; A61P 25/04 20060101 A61P025/04; A61P 25/18 20060101
A61P025/18; A61P 25/24 20060101 A61P025/24; A61P 25/30 20060101
A61P025/30; C07D 487/10 20060101 C07D487/10; A61P 25/00 20060101
A61P025/00 |
Claims
1. A compound represented by Formula I: ##STR00025## and
pharmaceutically acceptable salts, stereoisomers, and N-oxides
thereof; wherein T is, independently for each occurrence,
CR.sub.4R.sub.4 , and n is 0, 1, 2 or 3; A is optionally present
and is selected from phenyl or pyridine, wherein A is optionally
substituted by one or more substituents selected from R.sub.a;
R.sub.1 is selected from the group consisting of H, hydroxyl,
--S(O).sub.2--C.sub.1-C.sub.4alkyl; --SO.sub.2,
C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4alkenyl, phenyl, R.sub.7, or
##STR00026## wherein C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4alkenyl,
or phenyl is optionally substituted by one or more substituents
selected from R.sub.a; X is CH or N; R.sub.3 and R.sub.3' are
independently selected from the group consisting of H, halogen,
hydroxyl, phenyl, C.sub.1-C.sub.1alkyl, amido, amine, or
C.sub.2-C.sub.4alkenyl, wherein C.sub.1-C.sub.4alkyl,
C.sub.2-C.sub.4alkenyl and phenyl are optionally substituted by one
or more substituents selected from R.sub.a; R.sub.4 and R.sub.4'
are independently selected from the group consisting of H, halogen,
hydroxyl, phenyl, C.sub.1-C.sub.4alkyl, amido, amine,
C.sub.1-C.sub.4alkoxy or C.sub.2-C.sub.4alkenyl, wherein
C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4alkenyl,
C.sub.1-C.sub.4alkoxy, and phenyl are optionally substituted by one
or more substituents selected from R.sub.a; R.sub.2 is selected
from the group consisting of H, R.sub.7, --S(O).sub.2,
S(O).sub.2--C.sub.1-C.sub.4alkyl, hydroxyl, or phenyl wherein
C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4 alkenyl and phenyl are
optionally substituted by one or more substituents selected from
R.sub.a; R.sub.5 and R.sub.5' are each independently selected from
group consisting of H, halogen, C.sub.1-C.sub.4alkyl,
C.sub.1-C.sub.4alkoxy, C.sub.2-C.sub.4alkenyl, cyano, amino,
phenyl, and hydroxyl, wherein C.sub.1-C.sub.4alkyl,
C.sub.2-C.sub.4alkenyl and phenyl are optionally substituted by one
or more substituents selected from R.sub.a; R.sub.7 is selected
from group consisting of --C(O)--C.sub.1-C.sub.4alkyl or
C(O)--O--C.sub.1-C.sub.4alkyl, wherein C.sub.1-C.sub.4 alkyl is
optionally substituted by 1, 2 or 3 substituents selected from
R.sub.b; R.sub.8 is selected from group consisting of H,
--C(O)--C.sub.1-C.sub.4 alkyl or C(O)--O--C.sub.1-C.sub.4 alkyl,
wherein C.sub.1-C.sub.4alkyl is optionally substituted by 1, 2 or 3
substituents selected from R.sub.a; R.sub.a is selected,
independently for each occurrence, from carboxy, hydroxyl, halogen,
amino, phenyl, C.sub.1-C.sub.4 alkyl, and C.sub.1-C.sub.4 alkoxy;
R.sub.b is selected, independently for each occurrence, from the
group consisting of carboxy, hydroxyl, halogen, amino, phenyl,
C.sub.1-C.sub.4 alkyl, C.sub.1-C.sub.4 alkoxy, and --NH--R.sub.c;
and R.sub.c is selected, independently for each occurrence,
--C(O)--O--C.sub.1-C.sub.4alkyl; and
--C(O)--C.sub.1-C.sub.4alkyl.
2. The compound of claim 1, represented by: ##STR00027## wherein
R.sub.1 is C(O)--C.sub.2-C.sub.4alkyl, wherein C.sub.2-C.sub.4alkyl
is substituted at one carbon with NH.sub.2 or --N-carbobenzyloxy
and at a different carbon by hydroxyl.
3. The compound of claim 1, wherein R.sub.1 is
C(O)--O--C.sub.1-C.sub.4alkyl, wherein C.sub.1-C.sub.4alkyl is
substituted by phenyl.
4. The compound of claim 3, wherein R.sub.1 is carbobenzyloxy.
5. The compound of claim 1, wherein R.sub.1 is: ##STR00028##
wherein: X is N; R.sub.5' is H; and R.sub.8 is
C(O)--C.sub.2-C.sub.4alkyl, wherein C.sub.2-C.sub.4alkyl is
substituted at one carbon with NH.sub.2 or --N-carbobenzyloxy and
at a different carbon by hydroxyl.
6. The compound of claim 1, wherein R.sub.3 is phenyl.
7. The compound of claim 1, wherein R.sub.3 is H.
8. The compound of claim 1, wherein R.sub.2 is
--C(O)--C.sub.2-C.sub.4alkyl, substituted at one carbon with
NH.sub.2 and another carbon with hydroxyl.
9. The compound of claim 1, wherein C.sub.1-C.sub.4alkyl is
selected from the group consisting of methyl, ethyl, propyl,
n-butyl or t-butyl, and wherein said C.sub.1-C.sub.4alkyl is
optionally substituted by one, two, or three substituents selected
from the group consisting of F, Cl, or Br.
10. The compound of claim 1, wherein the compound is represented
by: ##STR00029##
11. A compound represented by formula II: ##STR00030## and
pharmaceutically acceptable salts, stereoisomers and N-oxides
thereof; wherein R.sub.1 is selected from the group consisting of
H, hydroxyl, --S(O).sub.2--C.sub.1-C.sub.4alkyl; --SO.sub.2,
C.sub.1-C.sub.4alkyl; R.sub.7, or ##STR00031## X is CH or N;
R.sub.3 and R.sub.3' are each independently selected from the group
consisting of H, halogen, hydroxyl, phenyl, C.sub.1-C.sub.4alkyl,
amido, amine, or C.sub.2-C.sub.4alkenyl, wherein
C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4alkenyl and phenyl are
optionally substituted by one or more substituents selected from
Ra; R.sub.2 is selected from the group consisting of H, R.sub.7,
--S(O).sub.2, S(O).sub.2--C.sub.1-C.sub.4alkyl, C.sub.1-C.sub.4
alkyl, hydroxyl, or phenyl wherein C.sub.1-C.sub.4alkyl,
C.sub.2-C.sub.4 alkenyl and phenyl are optionally substituted by
one or more substituents selected from R.sub.a; R.sub.5 is selected
from group consisting of H, halogen, C.sub.1-C.sub.4 alkyl,
C.sub.1-C.sub.4 alkoxy, C.sub.2-C.sub.4 alkenyl, cyano, amino,
phenyl, and hydroxyl, wherein C.sub.1-C.sub.4alkyl,
C.sub.2-C.sub.4alkenyl and phenyl are optionally substituted by one
or more substituents selected from R.sub.a; R.sub.6 is selected
from group consisting of H, halogen, C.sub.1-C.sub.4 alkyl,
C.sub.1-C.sub.4 alkoxy, C.sub.2-C.sub.4alkenyl, cyano, amino,
phenyl, and hydroxyl wherein C.sub.1-C.sub.4 alkyl,
C.sub.2-C.sub.4alkenyl and phenyl are optionally substituted by 1,
2 or 3 substituents selected from R.sub.a; R.sub.7 is selected from
group consisting of --C(O)--C.sub.1-C.sub.4alkyl or
--C(O)--O--C.sub.1-C.sub.4alkyl, wherein C.sub.1-C.sub.4 alkyl is
optionally substituted by 1, 2 or 3 substituents selected from
R.sub.b; or or R.sub.1 and R.sub.6, taken together with formula II
form: ##STR00032## R.sub.8 is selected from group consisting of H,
--C(O)--C.sub.1-C.sub.4alkyl or C(O)--O--C.sub.1-C.sub.4 alkyl,
wherein C.sub.1-C.sub.4alkyl is optionally substituted by 1, 2 or 3
substituents selected from R.sub.a; R.sub.a is selected,
independently for each occurrence, from carboxy, hydroxyl, halogen,
amino, phenyl, C.sub.1-C.sub.4alkyl, and C.sub.1-C.sub.4alkoxy;
R.sub.b is selected, independently for each occurrence, from the
group consisting of carboxy, hydroxyl, halogen, amino, phenyl,
C.sub.1-C.sub.4alkyl, C.sub.1-C.sub.4alkoxy, and --NH--R.sub.c; and
R.sub.c is selected, independently for each occurrence,
--C(O)--O--C.sub.1-C.sub.4alkyl; and
--C(O)--C.sub.1-C.sub.4alkyl.
12. The compound of claim 1, wherein R.sub.1 is selected from the
group consisting of: ##STR00033##
13. The compound of claiml represented by: ##STR00034##
14. The compound of claim 1, wherein the compound is selected from
the group consisting of: ##STR00035##
15. A compound of claim 1, which is capable of generating an
enhanced single shock evoked NMDA receptor-gated single neuron
conductance (I.sub.NMDA) in hippocampal CA1 pyramidal neurons at
concentrations of 100 nM to 1 .mu.M.
16. A non-peptidyl compound selected from the group consisting of:
##STR00036## ##STR00037## ##STR00038## or pharmaceutically
acceptable salts, stereoisomers and N-oxides thereof.
17. A method for treating a cognitive disorder comprising
administering to an patient in need thereof an effective amount of
a compound of claim 1.
18. The method of claim 17, wherein the cognitive disorder is
associated with memory loss or impaired learning.
19. The method of claim 19, wherein the compound is
##STR00039##
20. The method of claim 19, wherein the compound is administered
orally.
21. A pharmaceutically acceptable composition comprising a compound
of any one of claims 1-16, and a pharmaceutically acceptable
excipient.
22. The composition of claim 21, wherein the composition is
suitable for oral administration to a patient.
23. A method for treating neuropathic pain in a patient in need
thereof comprising administering an effective amount of a compound
of claim 1.
24. A method for treating depression, obsessive-compulsive
disorder, or schizophrenia in a patient in need thereof comprising
administering an effective amount of a compound of claim 1.
25. A method for treating post traumatic stress disorder, an
alcohol dependency disorder, or an addiction to an addictive drug
in a patient in need thereof comprising administering an effective
amount of a compound of claim 1.
26. The compound represented by: ##STR00040## and pharmaceutically
acceptable salts, stereoisomers, and N-oxides thereof.
27. A composition comprising the compound of claim 26, and a
pharmaceutically acceptable carrier.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of International
Application No. PCT/US2009/057401, filed Sep. 18, 2009, which in
turn claims priority to U.S. Ser. No. 61/098,088, filed Sep. 18,
2008, both of which are hereby incorporated by reference in their
entirety.
BACKGROUND
[0002] An N-methyl-d-aspartate (NMDA) receptor is a postsynaptic,
ionotropic receptor that is responsive to, inter alia, the
excitatory amino acids glutamate and glycine and the synthetic
compound NMDA. The NMDA receptor controls the flow of both divalent
and monovalent ions into the postsynaptic neural cell through a
receptor associated channel (Foster et al., Nature 1987,
329:395-396; Mayer et al., Trends in Pharmacol. Sci. 1990,
11:254-260). The NMDA receptor has been implicated during
development in specifying neuronal architecture and synaptic
connectivity, and may be involved in experience-dependent synaptic
modifications. In addition, NMDA receptors are also thought to be
involved in long term potentiation and central nervous system
disorders.
[0003] The NMDA receptor plays a major role in the synaptic
plasticity that underlies many higher cognitive functions, such as
memory acquisition, retention and learning, as well as in certain
cognitive pathways and in the perception of pain (Collingridge et
al., The NMDA Receptor, Oxford University Press, 1994). In
addition, certain properties of NMDA receptors suggest that they
may be involved in the information-processing in the brain that
underlies consciousness itself
[0004] The NMDA receptor has drawn particular interest since it
appears to be involved in a broad spectrum of CNS disorders. For
instance, during brain ischemia caused by stroke or traumatic
injury, excessive amounts of the excitatory amino acid glutamate
are released from damaged or oxygen deprived neurons. This excess
glutamate binds to the NMDA receptors which opens their
ligand-gated ion channels; in turn the calcium influx produces a
high level of intracellular calcium which activates a biochemical
cascade resulting in protein degradation and cell death. This
phenomenon, known as excitotoxicity, is also thought to be
responsible for the neurological damage associated with other
disorders ranging from hypoglycemia and cardiac arrest to epilepsy.
In addition, there are preliminary reports indicating similar
involvement in the chronic neurodegeneration of Huntington's,
Parkinson's, and Alzheimer's diseases. Activation of the NMDA
receptor has been shown to be responsible for post-stroke
convulsions, and, in certain models of epilepsy, activation of the
NMDA receptor has been shown to be necessary for the generation of
seizures. Neuropsychiatric involvement of the NMDA receptor has
also been recognized since blockage of the NMDA receptor Ca.sup.++
channel by the animal anesthetic PCP (phencyclidine) produces a
psychotic state in humans similar to schizophrenia (reviewed in
Johnson, K. and Jones, S., 1990). Further, NMDA receptors have also
been implicated in certain types of spatial learning.
[0005] The NMDA receptor is believed to consist of several protein
chains embedded in the postsynaptic membrane. The first two types
of subunits discovered so far form a large extracellular region,
which probably contains most of the allosteric binding sites,
several transmembrane regions looped and folded so as to form a
pore or channel, which is permeable to Ca.sup.+, and a carboxyl
terminal region. The opening and closing of the channel is
regulated by the binding of various ligands to domains (allosteric
sites) of the protein residing on the extracellular surface. The
binding of the ligands is thought to affect a conformational change
in the overall structure of the protein which is ultimately
reflected in the channel opening, partially opening, partially
closing, or closing.
[0006] NMDA receptor compounds may exert dual (agonist/antagonist)
effect on the NMDA receptor through the allosteric sites. These
compounds are typically termed "partial agonists". In the presence
of the principal site ligand, a partial agonist will displace some
of the ligand and thus decrease Ca.sup.++ flow through the
receptor. In the absence of or lowered level of the principal site
ligand, the partial agonist acts to increase Ca.sup.-+ flow through
the receptor channel.
[0007] A need continues to exist in the art for novel and more
specific/potent compounds that are capable of binding the glycine
binding site of NMDA receptors, and provide pharmaceutical
benefits. In addition, a need continues to exist in the medical
arts for an orally deliverable forms of such compounds.
SUMMARY
[0008] Provided herein, at least in part, are compounds that are
NMDA modulators, for example, partial agonists of NMDA. For
example, disclosed herein are compounds represented by Formula
I:
##STR00001##
and pharmaceutically acceptable salts, stereoisomers, and N-oxides
thereof; wherein [0009] T is, independently for each occurrence,
CR.sub.4R.sub.4', and n is 0, 1, 2 or 3; [0010] A is optionally
present and is selected from phenyl or pyridine, wherein A is
optionally substituted by one or more substituents selected from
R.sub.a; [0011] R.sub.1 is selected from the group consisting of H,
hydroxyl, --S(O).sub.2--C.sub.1-C.sub.4alkyl; --SO.sub.2,
C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4alkenyl, phenyl, R.sub.7,
or
##STR00002##
[0011] wherein C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4alkenyl, or
phenyl is optionally substituted by one or more substituents
selected from R.sub.a; [0012] X is CH or N; [0013] R.sub.3 and
R.sub.3' are independently selected from the group consisting of H,
halogen, hydroxyl, phenyl, C.sub.1-C.sub.4alkyl, amido, amine, or
C.sub.2-C.sub.4alkenyl, wherein C.sub.1-C.sub.4alkyl,
C.sub.2-C.sub.4alkenyl and phenyl are optionally substituted by one
or more substituents selected from R.sub.a; [0014] R.sub.4 and
R.sub.4' are independently selected from the group consisting of H,
halogen, hydroxyl, phenyl, C.sub.1-C.sub.4alkyl, amido, amine,
C.sub.1-C.sub.4alkoxy or C.sub.2-C.sub.4alkenyl, wherein
C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4alkenyl,
C.sub.1-C.sub.4alkoxy, and phenyl are optionally substituted by one
or more substituents selected from R.sub.a; [0015] R.sub.2 is
selected from the group consisting of H, R.sub.7, --S(O).sub.2,
S(O).sub.2--C.sub.1-C.sub.4alkyl, C.sub.1-C.sub.4alkyl, hydroxyl,
or phenyl wherein C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4 alkenyl and
phenyl are optionally substituted by one or more substituents
selected from R.sub.a; [0016] R.sub.5 and R.sub.5' are each
independently selected from group consisting of H, halogen,
C.sub.1-C.sub.4alkyl, C.sub.1-C.sub.4alkoxy,
C.sub.2-C.sub.4alkenyl, cyano, amino, phenyl, and hydroxyl, wherein
C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4alkenyl and phenyl are
optionally substituted by one or more substituents selected from
R.sub.a; [0017] R.sub.7 is selected from group consisting of
--C(O)--C.sub.1-C.sub.4alkyl or C(O)--O--C.sub.1-C.sub.4alkyl,
wherein C.sub.1-C.sub.4 alkyl is optionally substituted by 1, 2 or
3 substituents selected from R.sub.b; [0018] R.sub.8 is selected
from group consisting of H, --C(O)--C.sub.1-C.sub.4 alkyl or
C(O)--O--C.sub.1-C.sub.4 alkyl, wherein C.sub.1-C.sub.4alkyl is
optionally substituted by 1, 2 or 3 substituents selected from
R.sub.a; [0019] R.sub.a is selected, independently for each
occurrence, from carboxy, hydroxyl, halogen, amino, phenyl,
C.sub.1-C.sub.4 alkyl, and C.sub.1-C.sub.4 alkoxy; [0020] R.sub.b
is selected, independently for each occurrence, from the group
consisting of carboxy, hydroxyl, halogen, amino, phenyl,
C.sub.1-C.sub.4 alkyl, C.sub.1-C.sub.4 alkoxy, and --NH--R.sub.c;
and [0021] R.sub.c is selected, independently for each occurrence,
--C(O)--O--C.sub.1-C.sub.4alkyl; and
--C(O)--C.sub.1-C.sub.4alkyl.
[0022] Also provided herein are pharmaceutically acceptable
compositions comprising a disclosed compound, and a
pharmaceutically acceptable excipient. For example, such
compositions may be suitable for oral administration to a
patient.
[0023] A method for treating a cognitive disorder, such as a
disorder associated with memory loss or impaired learning
comprising administering to an patient in need thereof an effective
amount of a disclosed compound. For example, provided herein are
methods of treating or ameliorating memory loss or impaired
learning in a patient in need thereof.
[0024] In an embodiment, methods for treating neuropathic pain in a
patient in need thereof comprising administering an effective
amount of a disclosed compound is provided.
[0025] Also disclosed herein are methods for treating depression,
obsessive-compulsive disorder, or schizophrenia in a patient in
need thereof comprising administering an effective amount of a
disclosed compound. In another embodiment, methods for treating
post traumatic stress disorder, an alcohol dependency disorder, or
an addiction to an addictive drug in a patient in need thereof
comprising administering an effective amount of a disclosed
compounds are provided.
DESCRIPTION OF FIGURES
[0026] FIGS. 1A-1D indicate that a disclosed compound (AK52)
biphasically alters postsynaptic NMDA receptor-mediated excitatory
postsynaptic currents (e.p.s.c.s) at Shaffer collateral-CA1
synapses, and selectively enhances induction of LTP. 1A: Time
course of the marked reduction by AK52 (1 .mu.M; solid bar) of the
NMDA component of Schaffer collateral-evoked e.p.s.c.s in CA1
pyramidal neurons. (Each point is the mean.+-.SEM of e.p.s.c.
peNRXe amplitude of 5 cells.) 1B: Time course of the enhancement of
a ten-fold lower concentration of AK52 (100 NM; grey bar) of the
NMDA component of Schaffer collateral-evoked e.p.s.c.s. in CA1
pyramidal neurons. (Each point is the mean.+-.SEM of e.p.s.c. peNRX
amplitude of 5 cells). 1C: Time course of LTD induced by a low
frequency stimulus train (2 Hz/10 min; Starting at arrow) at
Schaffer collateral--CA1 synapses in slices pre-treated with 1
.mu.M (filled circles; n=10) and 100 nM (filled diamonds; n=6)
NRX-10,052, compared to control, untreated slices (open circles;
n-8). (Each point is the mean.+-.SEM of normalized extracellular
field EPSP slope of n slices.) 1D: Time course of experiments
comparing LTP induced by a high frequency stimulus train
(3.times.100 Hz/500 ms; arrow) at Schaffer collateral-CA1 synapses
in slices pre-treated with 1 .mu.M (filled circles; n=10 or 100 nM
(filled diamonds; n=8) NRX-10,052, compared to control, untreated
slices (open circles; n=15). (Each point is the mean.+-.SEM of
normalized field e.p.s.p. lsope of n slices).
[0027] FIGS. 2A-2E indicate a low concentration of a disclosed
compound B markedly enhances pharmacologically-isolated
postsynaptic NMDA receptor-mediated excitatory postsynaptic
currents (e.p.s.c.s) at Shaffer collateral-CA1 synapses and
potentiates LTP, while a 20-fold higher concentration reduces NMDA
e.p.s.c.s. 2A: Time course of the marked enhancement by Compound B
(50 nM; solid bar) of single shock Schaffer collateral-evoked
pharmacologically-isolated NMDA e.p.s.c.s. recorded in CA1
pyramidal neurons. 2B: Time course of the enhancement by compound B
(50 nM; solid bar) of burst-evoked (4 pulses/100 Hz) NMDA
e.p.s.c.s. 2C: Time course of the marked reduction by compound B (1
.mu.M; solid bar) of single shock Schaffer collateral-evoked NMDA
e.p.s.c.s. recorded in CA1 pyramidal neurons. 2D: Time course of
the reduction by compound B (1 .mu.M; solid bar) of burst-evoked (4
pulses 100 Hz) Schaffer collateral-evoked NMDA e.p.s.c.s recorded
in CA1 pyramidal neurons. 2E: Enhancement of high frequency (100
Hz/500 ms.times.3; solid arrow) Schaffer collateral stimulus-evoked
LTP at synapses on CA1 pyramidal neurons by 50 nM Compound B
(filled circles) compared to control, untreated slices (open
circles). (Each point is the mean.+-.SEM of e.p.s.c. peNRX
amplitude of n cells.).
[0028] FIGS. 3A-3C demonstrate 100 nM and 1 .mu.M concentrations of
a disclosed compound (AK51) both enhance pharmacologically-isolated
postsynaptic NMDA receptor-mediated (e.p.s.c.s.) at Shaffer
collateral-CA1 synapse and potentiate LTP. 3A: Time course of the
marked enhancement by NRX-10,051 (100 nM; solid bar) of single
shock Schaffer collateral-evoked pharmacologically-isolated NMDA
e.p.s.c.s recorded in CA1 pyramidal neurons (n=x). 3B: Time course
of the enhancement by AK51 (1 .mu.M; solid bar) of single shock
Schaffer collateral-evoked pharmacologically-isolated NMDA
e.p.s.c.s recorded in CA1 pyramidal neurons (n=y). 3C: Enhancement
of high frequency (100 Hz/500 ms.times.3; solid arrow) Schaffer
collateral stimulus-evoked LTP at synapses on CA1 pyramidal neurons
by 100 nM ( ) and 1 .mu.M (filled circles) AK5151, compared to
control, untreated slices (open circles). 3D: Time course of LTD
induced by a low frequency stimulus train (2 Hz/10 min; starting at
arrow) at Schaffer collateral-CA1 synapses in slices pre-treated
with 1 .mu.M (filled circles; n=10) or 100 nM (filled diamonds; n=6
NRX-10,051, compared to control, untreated slices (open circles;
n=8). Each point is the mean.+-.EM of e.p.s.c. peNRX amplitude of n
cells.).
[0029] FIG. 4 indicates that a disclosed compound enhances NMDA
current and LTP. A: Time course of effect of 20 min bath
application of 100 nM AK51 (solid bar) on normalized
pharmacologically-isolated NMDA receptor-gated current in CA1
pyramidal neurons under whole-cell recording (mean.+-.SEM, n=5). B:
Time course of effect of 20 min bath application of 1 .mu.M AK51
(solid bar) on normalized pharmacologically-isolated NMDA
receptor-gated current in CA1 pyramidal neurons under whole-cell
recording (mean.+-.SEM, n=6). C: Time course of effect of bath
application of 100 nM AK51 (solid bar, filled circles, n=8)
compared to untreated control slices (open circles, n=6) on the
magnitude of long-term potentiation (LTP) of extracellular
excitatory postsynaptic potential slope (mean.+-.SEM, fEPSP)
induced by high-frequency Schaffer collateral stimulation
(arrow,2.times.100 Hz/500 msec). D: Time course of effect of bath
application of 1 .mu.M AK51 (solid bar, filled circles, n=8)
compared to untreated control slices (open circles, n=6) on the
magnitude of LTP of fEPSP slope (mean.+-.SEM) induced by
high-frequency Schaffer collateral stimulation (arrow,2.times.100
Hz/500 msec). E: Time course of effect of bath application of 1
.mu.M AK51 (solid bar, filled circles, n=10) compared to untreated
control slices (open circles, n=8) on the magnitude of long-term
depression of fEPSP slope (mean.+-.SEM) induced by low-frequency
Schaffer collateral stimulation (arrow, 2 Hz/10 min)
[0030] FIG. 5 depicts the results of a T-maze test in rats using a
disclosed compound.
[0031] FIG. 6 depicts the results of a formalin neuropathic pain
assay in rats.
[0032] FIG. 7 indicates that one isomer of a disclosed compound
AK-55-A potently enhances NMDA current and LTP, while AK-55-B does
not.
[0033] FIG. 8 depicts quantification by GC/MS and shows the area
under the curve for AK-51 and [2H7]proline internal standard and
was analyzed with GC/MS by selective ion monitoring following TBDMS
derivatization based on methods adapted from Wood et al. Journal of
Chromatography B, 831, 313-9 (2005). The quantitative range of the
assay for this compound was 0.312 pmol to 10 pmol column. The ions
utilized for SIM were 241.2 (this compound) and 350.3 (deuterated
proline). R2=0.9998 (Quadratic non-liner regression).
DETAILED DESCRIPTION
[0034] This disclosure is generally directed to compounds that are
capable of modulating NMDA, e.g. NMDA antagonists or partial
agonists, and compositions and/or methods of using the disclosed
compounds.
[0035] The following definitions are used throughout the
description of the present disclosure:
[0036] The term "alkenyl" as used herein refers to an unsaturated
straight or branched hydrocarbon having at least one carbon-carbon
double bond, such as a straight or branched group of 2-12, 2-10, or
2-6 carbon atoms, referred to herein as C.sub.2-C.sub.12alkenyl,
C.sub.2-C.sub.10alkenyl, and C.sub.2-C.sub.6alkenyl, respectively.
Exemplary alkenyl groups include, but are not limited to, vinyl,
allyl, butenyl, pentenyl, hexenyl, butadienyl, pentadienyl,
hexadienyl, 2-ethylhexenyl, 2-propyl-2-butenyl,
4-(2-methyl-3-butene)-pentenyl, etc.
[0037] The term "alkoxy" as used herein refers to an alkyl group
attached to an oxygen (--O-alkyl). Exemplary alkoxy groups include,
but are not limited to, groups with an alkyl group of 1-12, 1-8, or
1-6 carbon atoms, referred to herein as C.sub.1-C.sub.12alkoxy,
C.sub.1-C.sub.8alkoxy, and C.sub.1-C.sub.6alkoxy, respectively.
Exemplary alkoxy groups include, but are not limited to methoxy,
ethoxy, etc. Similarly, exemplary "alkenoxy" groups include, but
are not limited to vinyloxy, allyloxy, butenoxy, etc.
[0038] The term "alkyl" as used herein refers to a saturated
straight or branched hydrocarbon. Exemplary alkyl groups include,
but are not limited to, methyl, ethyl, propyl, isopropyl,
2-methyl-1-propyl, 2-methyl-2-propyl, 2-methyl-l-butyl,
3-methyl-1-butyl, 2-methyl-3-butyl, 2,2-dimethyl-1-propyl,
2-methyl-1-pentyl, 3-methyl-1-pentyl, 4-methyl-1-pentyl,
2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl-2-pentyl,
2,2-dimethyl-1-butyl, 3,3-dimethyl-1-butyl, 2-ethyl-1-butyl, butyl,
isobutyl, t-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl,
octyl, etc.
[0039] Alkyl, alkenyl and alkynyl groups can optionally be
substituted, if not indicated otherwise, with one or more groups
selected from alkoxy, alkyl, cycloalkyl, amino, halogen, and
--C(O)alkyl. In certain embodiments, the alkyl, alkenyl and alkynyl
groups are not substituted, i.e., they are unsubstituted.
[0040] The term "alkynyl" as used herein refers to an unsaturated
straight or branched hydrocarbon having at least one carbon-carbon
triple bond. Exemplary alkynyl groups include, but are not limited
to, ethynyl, propynyl, and butynyl.
[0041] The term "amide" or "amido" as used herein refers to a
radical of the form --R.sub.aC(O)N(R.sub.b)--,
--R.sub.aC(O)N(R.sub.b)R.sub.c--, or --C(O)NR.sub.bR.sub.c, wherein
R.sub.a, R.sub.b and R.sub.c are each independently selected from
alkoxy, alkyl, alkenyl, alkynyl, amide, amino, aryl, arylalkyl,
carbamate, cycloalkyl, ester, ether, formyl, halogen, haloalkyl,
heteroaryl, heterocyclyl, hydrogen, hydroxyl, ketone, and nitro.
The amide can be attached to another group through the carbon, the
nitrogen, R.sub.b, R.sub.c, or R.sub.a. The amide also may be
cyclic, for example R.sub.b and R.sub.c, R.sub.a and R.sub.b, or
R.sub.a and R.sub.c may be joined to form a 3- to 12-membered ring,
such as a 3- to 10-membered ring or a 5- to 6-membered ring. The
term "carboxamido" refers to the structure
--C(O)NR.sub.bR.sub.c.
[0042] The term "amine" or "amino" as used herein refers to a
radical of the form --NR.sub.dR.sub.e, where R.sub.d and R.sub.e
are independently selected from hydrogen, alkyl, alkenyl, alkynyl,
aryl, arylalkyl, cycloalkyl, haloalkyl, heteroaryl, and
heterocyclyl. The amino also may be cyclic, for example, R.sub.d
and R.sub.e are joined together with the N to form a 3- to
12-membered ring, e.g., morpholino or piperidinyl. The term amino
also includes the corresponding quaternary ammonium salt of any
amino group, e.g., --[N(Rd)(Re)(Rf)]+. Exemplary amino groups
include aminoalkyl groups, wherein at least one of R.sub.d,
R.sub.e, or R.sub.f is an alkyl group. In certain embodiment,
R.sub.d and R.sub.e are hydrogen or alkyl.
[0043] The terms "halo" or "halogen" or "Hal" as used herein refer
to F, Cl, Br, or I. The term "haloalkyl" as used herein refers to
an alkyl group substituted with one or more halogen atoms.
[0044] The terms "heterocyclyl" or "heterocyclic group" are
art-recognized and refer to saturated or partially unsaturated 3-
to 10-membered ring structures, alternatively 3- to 7-membered
rings, whose ring structures include one to four heteroatoms, such
as nitrogen, oxygen, and sulfur. Heterocycles may also be mono-,
bi-, or other multi-cyclic ring systems. A heterocycle may be fused
to one or more aryl, partially unsaturated, or saturated rings.
Heterocyclyl groups include, for example, biotinyl, chromenyl,
dihydrofuryl, dihydroindolyl, dihydropyranyl, dihydrothienyl,
dithiazolyl, homopiperidinyl, imidazolidinyl, isoquinolyl,
isothiazolidinyl, isoxazolidinyl, morpholinyl, oxolanyl,
oxazolidinyl, phenoxanthenyl, piperazinyl, piperidinyl, pyranyl,
pyrazolidinyl, pyrazolinyl, pyridyl, pyrimidinyl, pyrrolidinyl,
pyrrolidin-2-onyl, pyrrolinyl, tetrahydrofuryl,
tetrahydroisoquinolyl, tetrahydropyranyl, tetrahydroquinolyl,
thiazolidinyl, thiolanyl, thiomorpholinyl, thiopyranyl, xanthenyl,
lactones, lactams such as azetidinones and pyrrolidinones, sultams,
sultones, and the like. The heterocyclic ring may be substituted at
one or more positions with substituents such as alkanoyl, alkoxy,
alkyl, alkenyl, alkynyl, amido, amidino, amino, aryl, arylalkyl,
azido, carbamate, carbonate, carboxy, cyano, cycloalkyl, ester,
ether, formyl, halogen, haloalkyl, heteroaryl, heterocyclyl,
hydroxyl, imino, ketone, nitro, phosphate, phosphonato,
phosphinato, sulfate, sulfide, sulfonamido, sulfonyl and
thiocarbonyl. In certain embodiments, the heterocyclic group is not
substituted, i.e., the heterocyclic group is unsubstituted.
[0045] The term "heterocycloalkyl" is art-recognized and refers to
a saturated heterocyclyl group as defined above. The term
"heterocyclylalkoxy" as used herein refers to a heterocyclyl
attached to an alkoxy group. The term "heterocyclyloxyalkyl" refers
to a heterocyclyl attached to an oxygen (--O--), which is attached
to an alkyl group.
[0046] The terms "hydroxy" and "hydroxyl" as used herein refers to
the radical --OH.
[0047] "Pharmaceutically or pharmacologically acceptable" include
molecular entities and compositions that do not produce an adverse,
allergic or other untoward reaction when administered to an animal,
or a human, as appropriate. "For human administration, preparations
should meet sterility, pyrogenicity, general safety and purity
standards as required by FDA Office of Biologics standards
[0048] As used in the present disclosure, the term "partial NMDA
receptor agonist" is defined as a compound that is capable of
binding to a glycine binding site of an NMDA receptor; at low
concentrations a NMDA receptor agonist acts substantially as
agonist and at high concentrations it acts substantially as an
antagonist. These concentrations are experimentally determined for
each and every "partial agonist.
[0049] As used herein "pharmaceutically acceptable carrier" or
"exipient" includes any and all solvents, dispersion media,
coatings, antibacterial and antifungal agents, isotonic and
absorption delaying agents, and the like that are physiologically
compatible. In one embodiment, the carrier is suitable for
parenteral administration. Alternatively, the carrier can be
suitable for intravenous, intraperitoneal, intramuscular,
sublingual or oral administration. Pharmaceutically acceptable
carriers include sterile aqueous solutions or dispersions and
sterile powders for the extemporaneous preparation of sterile
injectable solutions or dispersion. The use of such media and
agents for pharmaceutically active substances is well known in the
art. Except insofar as any conventional media or agent is
incompatible with the active compound, use thereof in the
pharmaceutical compositions of the invention is contemplated.
Supplementary active compounds can also be incorporated into the
compositions.
[0050] The term "pharmaceutically acceptable salt(s)" as used
herein refers to salts of acidic or basic groups that may be
present in compounds used in the present compositions. Compounds
included in the present compositions that are basic in nature are
capable of forming a wide variety of salts with various inorganic
and organic acids. The acids that may be used to prepare
pharmaceutically acceptable acid addition salts of such basic
compounds are those that form non-toxic acid addition salts, i.e.,
salts containing pharmacologically acceptable anions, including but
not limited to malate, oxalate, chloride, bromide, iodide, nitrate,
sulfate, bisulfate, phosphate, acid phosphate, isonicotinate,
acetate, lactate, salicylate, citrate, tartrate, oleate, tannate,
pantothenate, bitartrate, ascorbate, succinate, maleate,
gentisinate, fumarate, gluconate, glucaronate, saccharate, formate,
benzoate, glutamate, methanesulfonate, ethanesulfonate,
benzenesulfonate, p-toluenesulfonate and pamoate (i.e.,
1,1'-methylene-bis-(2-hydroxy-3-naphthoate)) salts. Compounds
included in the present compositions that include an amino moiety
may form pharmaceutically acceptable salts with various amino
acids, in addition to the acids mentioned above. Compounds included
in the present compositions that are acidic in nature are capable
of forming base salts with various pharmacologically acceptable
cations. Examples of such salts include alkali metal or alkaline
earth metal salts and, particularly, calcium, magnesium, sodium,
lithium, zinc, potassium, and iron salts.
[0051] The compounds of the disclosure may contain one or more
chiral centers and/or double bonds and, therefore, exist as
stereoisomers, such as geometric isomers, enantiomers or
diastereomers. The term "stereoisomers" when used herein consist of
all geometric isomers, enantiomers or diastereomers. These
compounds may be designated by the symbols "R" or "S," depending on
the configuration of substituents around the stereogenic carbon
atom. The present invention encompasses various stereoisomers of
these compounds and mixtures thereof. Stereoisomers include
enantiomers and diastereomers. Mixtures of enantiomers or
diastereomers may be designated "(.+-.)" in nomenclature, but the
skilled artisan will recognize that a structure may denote a chiral
center implicitly.
[0052] Individual stereoisomers of compounds of the present
invention can be prepared synthetically from commercially available
starting materials that contain asymmetric or stereogenic centers,
or by preparation of racemic mixtures followed by resolution
methods well known to those of ordinary skill in the art. These
methods of resolution are exemplified by (1) attachment of a
mixture of enantiomers to a chiral auxiliary, separation of the
resulting mixture of diastereomers by recrystallization or
chromatography and liberation of the optically pure product from
the auxiliary, (2) salt formation employing an optically active
resolving agent, or (3) direct separation of the mixture of optical
enantiomers on chiral chromatographic columns. Stereoisomeric
mixtures can also be resolved into their component stereoisomers by
well known methods, such as chiral-phase gas chromatography,
chiral-phase high performance liquid chromatography, crystallizing
the compound as a chiral salt complex, or crystallizing the
compound in a chiral solvent. Stereoisomers can also be obtained
from stereomerically-pure intermediates, reagents, and catalysts by
well known asymmetric synthetic methods.
[0053] Geometric isomers can also exist in the compounds of the
present invention. The symbol denotes a bond that may be a single,
double or triple bond as described herein. The present invention
encompasses the various geometric isomers and mixtures thereof
resulting from the arrangement of substituents around a
carbon-carbon double bond or arrangement of substituents around a
carbocyclic ring. Substituents around a carbon-carbon double bond
are designated as being in the "Z" or "E" configuration wherein the
terms "Z" and "E" are used in accordance with IUPAC standards.
Unless otherwise specified, structures depicting double bonds
encompass both the "E" and "Z" isomers.
[0054] Substituents around a carbon-carbon double bond
alternatively can be referred to as "cis" or "trans," where "cis"
represents substituents on the same side of the double bond and
"trans" represents substituents on opposite sides of the double
bond. The arrangement of substituents around a carbocyclic ring are
designated as "cis" or "trans." The term "cis" represents
substituents on the same side of the plane of the ring and the term
"trans" represents substituents on opposite sides of the plane of
the ring. Mixtures of compounds wherein the substituents are
disposed on both the same and opposite sides of plane of the ring
are designated "cis/trans."
[0055] The compounds disclosed herein can exist in solvated as well
as unsolvated forms with pharmaceutically acceptable solvents such
as water, ethanol, and the like, and it is intended that the
invention embrace both solvated and unsolvated forms. In one
embodiment, the compound is amorphous. In one embodiment, the
compound is a polymorph. In another embodiment, the compound is in
a crystalline form.
[0056] The invention also embraces isotopically labeled compounds
of the invention which are identical to those recited herein,
except that one or more atoms are replaced by an atom having an
atomic mass or mass number different from the atomic mass or mass
number usually found in nature. Examples of isotopes that can be
incorporated into compounds of the invention include isotopes of
hydrogen, carbon, nitrogen, oxygen, phosphorus, fluorine and
chlorine, such as .sup.2H, .sup.3H, .sup.13C, .sup.14C, .sup.15N,
.sup.18O, .sup.17O, .sup.31P, .sup.32P, .sup.35S, .sup.18F, and
.sup.36Cl, respectively.
[0057] Certain isotopically-labeled disclosed compounds (e.g.,
those labeled with .sup.3H and .sup.14C) are useful in compound
and/or substrate tissue distribution assays. Tritiated (i.e.,
.sup.3H) and carbon-14 (i.e., .sup.14C) isotopes are particularly
preferred for their ease of preparation and detectability. Further,
substitution with heavier isotopes such as deuterium (i.e.,
.sup.2H) may afford certain therapeutic advantages resulting from
greater metabolic stability (e.g., increased in vivo half-life or
reduced dosage requirements) and hence may be preferred in some
circumstances. Isotopically labeled compounds of the invention can
generally be prepared by following procedures analogous to those
disclosed in the e.g., Examples herein by substituting an
isotopically labeled reagent for a non-isotopically labeled
reagent.
[0058] As used in the present disclosure, "NMDA" is defined as
N-methyl-d-aspartate.
[0059] In the present specification, the term "therapeutically
effective amount" means the amount of the subject compound that
will elicit the biological or medical response of a tissue, system,
animal or human that is being sought by the researcher,
veterinarian, medical doctor or other clinician. The compounds of
the invention are administered in therapeutically effective amounts
to treat a disease. Alternatively, a therapeutically effective
amount of a compound is the quantity required to achieve a desired
therapeutic and/or prophylactic effect, such as an amount which
results in defined as that amount needed to give maximal
enhancement of a behavior (for example, learning), physiological
response (for example, LTP induction), or inhibition of neuropathic
pain.
Compounds
[0060] Disclosed compounds include those represented by Formula
I:
##STR00003## [0061] and pharmaceutically acceptable salts,
stereoisomers, and N-oxides thereof; wherein [0062] T is,
independently for each occurrence, CR.sub.4R.sub.4', and n is 0, 1,
2 or 3; [0063] A is optionally present and is selected from phenyl
or pyridine, wherein A is optionally substituted by one or more
substituents selected from R.sub.a; [0064] R.sub.1 is selected from
the group consisting of H, hydroxyl,
--S(O).sub.2--C.sub.1-C.sub.4alkyl; --SO.sub.2,
C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4alkenyl, phenyl, R.sub.7,
or
##STR00004##
[0064] wherein C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4alkenyl, or
phenyl is optionally substituted by one or more substituents
selected from R.sub.a; [0065] X is CH or N; [0066] R.sub.3 and
R.sub.3' are independently selected from the group consisting of H,
halogen, hydroxyl, phenyl, C.sub.1-C.sub.4alkyl, amido, amine, or
C.sub.2-C.sub.4alkenyl, wherein C.sub.1-C.sub.4alkyl,
C.sub.2-C.sub.4alkenyl and phenyl are optionally substituted by one
or more substituents selected from R.sub.a; [0067] R.sub.4 and
R.sub.4' are independently selected from the group consisting of H,
halogen, hydroxyl, phenyl, C.sub.1-C.sub.4alkyl, amido, amine,
C.sub.1-C.sub.4alkoxy or C.sub.2-C.sub.4alkenyl, wherein
C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4alkenyl,
C.sub.1-C.sub.4alkoxy, and phenyl are optionally substituted by one
or more substituents selected from R.sub.a; [0068] R.sub.2 is
selected from the group consisting of H, R.sub.7, --S(O).sub.2,
S(O).sub.2--C.sub.1-C.sub.4alkyl, C.sub.1-C.sub.4alkyl, hydroxyl,
or phenyl wherein C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4 alkenyl and
phenyl are optionally substituted by one or more substituents
selected from R.sub.a; [0069] R.sub.5 and R.sub.5' are each
independently selected from group consisting of H, halogen,
C.sub.1-C.sub.4alkyl, C.sub.1-C.sub.4alkoxy,
C.sub.2-C.sub.4alkenyl, cyano, amino, phenyl, and hydroxyl, wherein
C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4alkenyl and phenyl are
optionally substituted by one or more substituents selected from
R.sub.a; [0070] R.sub.7 is selected from group consisting of
--C(O)--C.sub.1-C.sub.4alkyl or C(O)--O--C.sub.1-C.sub.4alkyl,
wherein C.sub.1-C.sub.4 alkyl is optionally substituted by 1, 2 or
3 substituents selected from R.sub.b; [0071] R.sub.8 is selected
from group consisting of H, --C(O)--C.sub.1-C.sub.4 alkyl or
C(O)--O--C.sub.1-C.sub.4 alkyl, wherein C.sub.1-C.sub.4alkyl is
optionally substituted by 1, 2 or 3 substituents selected from
R.sub.a; [0072] R.sub.a is selected, independently for each
occurrence, from carboxy, hydroxyl, halogen, amino, phenyl,
C.sub.1-C.sub.4 alkyl, and C.sub.1-C.sub.4 alkoxy; [0073] R.sub.b
is selected, independently for each occurrence, from the group
consisting of carboxy, hydroxyl, halogen, amino, phenyl,
C.sub.1-C.sub.4 alkyl, C.sub.1-C.sub.4 alkoxy, and --NH--R.sub.c;
and [0074] R.sub.c is selected, independently for each occurrence,
--C(O)--O--C.sub.1-C.sub.4alkyl; and
--C(O)--C.sub.1-C.sub.4alkyl.
[0075] For example, disclosed compounds may include those
represented by:
##STR00005##
wherein R.sub.1 is C(O)--C.sub.2-C.sub.4alkyl, wherein
C.sub.2-C.sub.4alkyl is substituted at one carbon with NH.sub.2 or
--N-carbobenzyloxy and at a different carbon by hydroxyl. For
example, R.sub.1 may be C(O)--O--C.sub.1--C.sub.4alkyl (e.g.,
methyl, ethyl, propyl, wherein C.sub.1-C.sub.4alkyl is substituted
by phenyl.
[0076] For example, R.sub.1 may be carbobenzyloxy, or may be
represented by:
##STR00006##
wherein X may be N; R.sub.5' may be H; and R.sub.8 may be
--C(O)--C.sub.2-C.sub.4alkyl (e.g. ethyl, propyl, n-butyl, or
t-butyl), wherein C.sub.2-C.sub.4alkyl is substituted at one carbon
with NH.sub.2 or --N-carbobenzyloxy and at a different carbon by
hydroxyl.
[0077] In certain embodiments, R.sub.3 may be phenyl (optionally
substituted as above), or may be H. R.sub.2 may be, in some
embodiments, a --C(O)--C.sub.2-C.sub.4alkyl, (e.g. ethyl, propyl,
n-butyl, or t-butyl), optionally substituted at one carbon with
NH.sub.2 and another carbon with hydroxyl.
[0078] For any contemplated R-group that includes
C.sub.1-C.sub.4alkyl (e.g. R.sub.1, R.sub.3, R.sub.5), the alkyl
may be selected from the group consisting of methyl, ethyl, propyl,
n-butyl or t-butyl, and wherein said C.sub.1-C.sub.4alkyl is
optionally substituted by one, two, or three substituents selected
from the group consisting of F, Cl, or Br.
[0079] Such compounds may have differing isomerizations, and in
some embodiments, may be represented by:
##STR00007##
[0080] In another embodiment, compounds represented by formula II
are contemplated:
##STR00008##
and pharmaceutically acceptable salts, stereoisomers and N-oxides
thereof; wherein [0081] R.sub.1 is selected from the group
consisting of H, hydroxyl, --S(O).sub.2--C.sub.1-C.sub.4alkyl;
--SO.sub.2, C.sub.1-C.sub.4alkyl; R.sub.7, or
[0081] ##STR00009## [0082] X is CH or N; [0083] R.sub.3 and
R.sub.3' are each independently selected from the group consisting
of H, halogen, hydroxyl, phenyl, C.sub.1-C.sub.4alkyl, amido,
amine, or C.sub.2-C.sub.4alkenyl, wherein C.sub.1-C.sub.4alkyl,
C.sub.2-C.sub.4alkenyl and phenyl are optionally substituted by one
or more substituents selected from Ra; [0084] R.sub.2 is selected
from the group consisting of H, R.sub.7, --S(O).sub.2,
S(O).sub.2--C.sub.1-C.sub.4alkyl, C.sub.1-C.sub.4alkyl, hydroxyl,
or phenyl wherein C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4 alkenyl and
phenyl are optionally substituted by one or more substituents
selected from R.sub.a; [0085] R.sub.5 is selected from group
consisting of H, halogen, C.sub.1-C.sub.4 alkyl, C.sub.1-C.sub.4
alkoxy, C.sub.2-C.sub.4 alkenyl, cyano, amino, phenyl, and
hydroxyl, wherein C.sub.1-C.sub.4alkyl, C.sub.2-C.sub.4alkenyl and
phenyl are optionally substituted by one or more substituents
selected from R.sub.a; [0086] R.sub.6 is selected from group
consisting of H, halogen, C.sub.1-C.sub.4 alkyl, C.sub.1-C.sub.4
alkoxy, C.sub.2-C.sub.4alkenyl, cyano, amino, phenyl, and hydroxyl
wherein C.sub.1-C.sub.4 alkyl, C.sub.2-C.sub.4alkenyl and phenyl
are optionally substituted by 1, 2 or 3 substituents selected from
R.sub.a; [0087] R.sub.7 is selected from group consisting of
--C(O)--C.sub.1-C.sub.4alkyl or --C(O)--O--C.sub.1-C.sub.4alkyl,
wherein C.sub.1-C.sub.4 alkyl is optionally substituted by 1, 2 or
3 substituents selected from R.sub.b; or [0088] or R.sub.1 and
R.sub.6, taken together with formula II form:
[0088] ##STR00010## [0089] R.sub.8 is selected from group
consisting of H, --C(O)--C.sub.1-C.sub.4alkyl or
C(O)--O--C.sub.1-C.sub.4 alkyl, wherein C.sub.1-C.sub.4alkyl is
optionally substituted by 1, 2 or 3 substituents selected from
R.sub.a; [0090] R.sub.a is selected, independently for each
occurrence, from carboxy, hydroxyl, halogen, amino, phenyl,
C.sub.1-C.sub.4alkyl, and C.sub.1-C.sub.4alkoxy; [0091] R.sub.b is
selected, independently for each occurrence, from the group
consisting of carboxy, hydroxyl, halogen, amino, phenyl,
C.sub.1-C.sub.4alkyl, C.sub.1-C.sub.4alkoxy, and --NH--R.sub.c; and
[0092] R.sub.c is selected, independently for each occurrence,
--C(O)--O--C.sub.1-C.sub.4alkyl; and
--C(O)--C.sub.1-C.sub.4alkyl.
[0093] In an exemplary embodiment, a R.sub.1 moiety of Formula I,
II, Ia or Ib may be selected from the group consisting of:
##STR00011##
[0094] Exemplary compounds include
##STR00012##
[0095] Disclosed herein are compounds selected from the group
consisting of:
##STR00013## ##STR00014## ##STR00015##
and pharmaceutically acceptable salts, stereoisomers, or N-oxides
thereof.
[0096] The compounds of the present disclosure and formulations
thereof are intended to include both a D-isomeric form, an
L-isomeric form, or a racemic mixture (both D- and L-isomeric
forms) of any one or more of the compounds. In addition, the
formulations of the compounds are intended to include any
combination or ratio of L-isomeric forms to D-isomeric forms of one
or more of the analogs described herein. These and other
formulations of the disclosed compounds comprising a greater ratio
of the D- and/or L-isomeric analog form may posses enhanced
therapeutic characteristic relative to racemic formulations of a
disclosed compounds or mixture of compounds. For example, disclosed
compounds may be enantiomers, e.g.:
##STR00016##
[0097] Disclosed compounds may provide for efficient cation channel
opening at the NMDA receptor, e.g. may bind or associate with the
glutamate site of the NMDA receptor to assist in opening the cation
channel. The disclosed compounds may be used to regulate (turn on
or turn off) the NMDA receptor through action as an agonist.
[0098] The compounds as described herein may be glycine site NMDA
receptor partial agonists. A partial agonist as used in this
context will be understood to mean that at a low concentration, the
analog acts as an agonist and at a high concentration, the analog
acts as an antagonist. Glycine binding is not inhibited by
glutamate or by competitive inhibitors of glutamate, and also does
not bind at the same site as glutamate on the NMDA receptor. A
second and separate binding site for glycine exists at the NMDA
receptor. The ligand-gated ion channel of the NMDA receptor is,
thus, under the control of at least these two distinct allosteric
sites. Disclosed compounds may be capable of binding or associating
with the glycine binding site of the NMDA receptor. In some
embodiments, disclosed compounds may possess a potency that is
10-fold or greater than the activity of existing NMDA receptor
glycine site partial agonists. For example, disclosed compounds may
possess a 10-fold to 20-fold enhanced potency compared to GLYX-13.
GLYX-13 is represented by:
##STR00017##
[0099] For example, provided herein are compounds that may be at
least about 20-fold more potent as compared to GLYX-13, as measured
by burst activated NMDA receptor-gated single neuron conductance
(I.sub.NMDA) in a culture of hippocampal CA1 pyramidal neurons at a
concentration of 50 nM. In another embodiment, a provided compound
may be capable of generating an enhanced single shock evoked NMDA
receptor-gated single neuron conductance (I.sub.NMDA) in
hippocampal CA1 pyramidal neurons at concentrations of 100 nM to 1
.mu.M. Disclosed compounds may have enhanced potency as compared to
GLYX-13 as measured by magnitude of long term potentiation (LTP) at
Schaffer collateral-CA-1 synapses in in vitro hippocampal
slices.
Synthetic Routes
[0100] The following schemes are representative synthetic that may
be used to prepare disclosed compounds and intermediates
thereof.
##STR00018##
##STR00019##
[0101] Ceric ammonium nitrate, or "CAN", is the chemical compound
with the formula (NH.sub.4).sub.2Ce(NO.sub.3).sub.6. This
orange-red, water-soluble salt is widely used as an oxidizing agent
in organic synthesis. This compound is used as a standard oxidant
in quantitative analysis.
[0102] PMP refers to p-methoxybenzylidene; Cbz refers to a
carbobenzyloxy radical that can be depicted as:
##STR00020##
Compositions.
[0103] In other aspects, formulations and compositions comprising
the disclosed compounds and optionally a pharmaceutically
acceptable excipient are provided. In some embodiments, a
contemplated formulation comprises a racemic mixture of one or more
of the disclosed compounds.
[0104] Contemplated formulations may be prepared in any of a
variety of forms for use. By way of example, and not limitation,
the compounds may be prepared in a formulation suitable for oral
administration, subcutaneous injection, or other methods for
administering an active agent to an animal known in the
pharmaceutical arts.
[0105] Amounts of a disclosed compound as described herein in a
formulation may vary according to factors such as the disease
state, age, sex, and weight of the individual. Dosage regimens may
be adjusted to provide the optimum therapeutic response. For
example, a single bolus may be administered, several divided doses
may be administered over time or the dose may be proportionally
reduced or increased as indicated by the exigencies of the
therapeutic situation. It is especially advantageous to formulate
parenteral compositions in dosage unit form for ease of
administration and uniformity of dosage. Dosage unit form as used
herein refers to physically discrete units suited as unitary
dosages for the mammalian subjects to be treated; each unit
containing a predetermined quantity of active compound calculated
to produce the desired therapeutic effect in association with the
required pharmaceutical carrier.
[0106] The specification for the dosage unit forms of the invention
are dictated by and directly dependent on (a) the unique
characteristics of the compound selected and the particular
therapeutic effect to be achieved, and (b) the limitations inherent
in the art of compounding such an active compound for the treatment
of sensitivity in individuals.
[0107] As used herein "pharmaceutically acceptable carrier" or
"excipient" includes any and all
[0108] Therapeutic compositions typically must be sterile and
stable under the conditions of manufacture and storage. The
composition can be formulated as a solution, microemulsion,
liposome, or other ordered structure suitable to high drug
concentration. The carrier can be a solvent or dispersion medium
containing, for example, water, ethanol, polyol (for example,
glycerol, propylene glycol, and liquid polyethylene glycol, and the
like), and suitable mixtures thereof. The proper fluidity can be
maintained, for example, by the use of a coating such as lecithin,
by the maintenance of the required particle size in the case of
dispersion and by the use of surfactants. In many cases, it will be
preferable to include isotonic agents, for example, sugars,
polyalcohols such as mannitol, sorbitol, or sodium chloride in the
composition. Prolonged absorption of the injectable compositions
can be brought about by including in the composition an agent which
delays absorption, for example, monostearate salts and gelatin.
[0109] The compounds can be administered in a time release
formulation, for example in a composition which includes a slow
release polymer. The compounds can be prepared with carriers that
will protect the compound against rapid release, such as a
controlled release formulation, including implants and
microencapsulated delivery systems. Biodegradable, biocompatible
polymers can be used, such as ethylene vinyl acetate,
polyanhydrides, polyglycolic acid, collagen, polyorthoesters,
polylactic acid and polylactic, polyglycolic copolymers (PLG). Many
methods for the preparation of such formulations are generally
known to those skilled in the art.
[0110] Sterile injectable solutions can be prepared by
incorporating the comound in the required amount in an appropriate
solvent with one or a combination of ingredients enumerated above,
as required, followed by filtered sterilization. Generally,
dispersions are prepared by incorporating the active compound into
a sterile vehicle which contains a basic dispersion medium and the
required other ingredients from those enumerated above. In the case
of sterile powders for the preparation of sterile injectable
solutions, the preferred methods of preparation are vacuum drying
and freeze-drying which yields a powder of the active ingredient
plus any additional desired ingredient from a previously
sterile-filtered solution thereof.
[0111] In accordance with an alternative aspect of the invention, a
compound may be formulated with one or more additional compounds
that enhance the solubility of the compound.
Methods
[0112] Methods for treating cognitive disorders and for enhancing
learning is provided. Such methods include administering a
pharmaceutically acceptable formulation of one or more of the
disclosed compounds to a patient in need thereof. Also contemplated
are methods of treating patients suffering from, memory deficits
associated with aging, schizophrenia, special learning disorders,
seizures, post-stroke convulsions, brain ischemia, hypoglycemia,
cardiac arrest, epilepsy, migraine, as well as Huntington's,
Parkinson's and Alzheimer's disease.
[0113] Other methods contemplated include the treatment of cerebral
ischemia, stroke, brain trauma, brain tumors, acute neuropathic
pain, chronic neuropathic pain, sleep disorders, drug addiction,
depression, certain vision disorders, ethanol withdrawal, anxiety,
and memory and learning disabilities. In yet another aspect, a
method for enhancing pain relief and for providing analgesia to an
animal is provided
EXAMPLES
[0114] The following examples are provided for illustrative
purposes only, and are not intended to limit the scope of the
disclosure.
Example 1
Synthesis of Pyrrolidine-Derived Spiro .beta.-Lactam
Derivatives
[0115] The following reaction sequence was used (Scheme A) to
synthesize Spiro Lactams. Hexahydro1,3,5-triazines, Cbz-L-proline
acid chloride and N-(Cbz) O-(benzylether)-L-threonine acid chloride
as starting materials.
##STR00021##
TABLE-US-00001 TABLE 1 HPLC Mass % (M.sup.+ Lot # Structure
Quantity Purity H) HNMR 4 ##STR00022## 20 mg 93 261 YES 5 (AK- 51)
##STR00023## 150 mg -- 127 YES (>95% purity) 8 ##STR00024## 17
mg 73 496 --
Example 2
Synthesis of Compounds and Intermediates
[0116] Spiro Lactam 3. The synthesis of C4 unsubstituted spiro
lactam 3 was conducted via Staudinger reaction of methyleneimine
derived from triazine 2. The [2+2]-cycle addition reaction between
the ketene derived from Cbz-L-proline acid chloride and the
methyleneimine was carried out in the following way: ketene was
generated by dehydrochlorination of the acid chloride with
triethylamine at -40.degree. C. for 45 min, and then a
dichloromethane solution of triazine 2 and boron trifluoride
etherate (which depolymerize the triazine) was added. After 12
hours, the corresponding spiro lactam 3 was obtained as a mixture
of enantiomers, with 30 to 50% yield. The oxidative removal of the
PMP group from spiro lactam 3 in the presence of CAN gave the
N-unsubstituted derivative spiro lactam 4, which upon treatment
with Pd(OH).sub.2/C gave the corresponding spiro lactam
intermediates 5.
[0117] Spiro lactam 4 was obtained in 93% purity (HPLC) after
purification by chromatography on silica gel. Spiro lactam 5 were
obtained with purities >90% purity (by NMR) after chromatography
on silica gel using gradient elution 20% to 70% Ethyl Acetate
Cyclohexane, in 50% yield.
Example 3
Synthetic Routes to Intermediate Compounds
[0118] Triazine 2. To a solution of p-anisidine (24.6 g, 200 mmol.)
in a mixture (500 mL) of ethyl acetate / water (1:1), cooled at
0.degree. C., an aqueous solution (17 mL) of formaldehyde (37%) was
added. The reaction mixture was stirred for 3 hours at 0.degree. C.
then 1 hour at room temperature, and the organic layer was
separated, washed with water (50 mL), and dried over
Na.sub.2SO.sub.4. The solvent was removed under vacuum, and a white
solid was obtained. This solid was washed once with diethyl ether
to provide 26.3 g (solid was dried at 40.degree. C. overnight) of
pure triazine 2 in 97% yield.
[0119] Spiro lactam Intermediates 3. To a stirred solution of the
N-benzyloxycarbonyl L-proline acid chloride (5 g, 18.7 mmol.) in
dry dichloromethane (65 mL) cooled to -40.degree. C., was added
dropwise dry triethylamine (10.4 mL, 74.7 mmol.). The solution
became yellow to confirm that the ketene was formed.
[0120] After 45 min at -40.degree. C., a purple solution of
triazine 2 (2.52 g, 6.16 mmol.) and BF.sub.3 OEt.sub.2 (2.37 mL,
18.7 mmol.), previously mixed in CH.sub.2Cl.sub.2 (35 mL), was
added dropwise. The mixture was allowed to warm slowly to room
temperature overnight and then quenched with saturated aqueous
NaHCO.sub.3. The aqueous layer was extracted twice with
CH.sub.2Cl.sub.2 (20 mL); the combined organic layers were washed
with brine (20 mL) and dried over anhydrous Na.sub.2SO.sub.4. The
solution was then concentrated and purified by column
chromatography over silica gel using gradient elution
100%/cyclohexane to 20% ethyl acetate/cyclohexane to give 7.01 g of
pure product with 37% yield.
[0121] Spiro lactam Intermediates 4. To a stirred solution of spiro
lactam 3 (2.4 g, 6.55 mmol.) in acetonitrile (49 mL) at -10.degree.
C., was added dropwise over 1 hour CAN (10.8 g, 19.6 mmol.),
previously dissolved in H.sub.2O (30 mL). After the addition was
complete, the mixture was stirred for 45 min (TLC showed no
remaining starting material). The reaction mixture was diluted with
ethyl acetate (100 mL) and saturated NaHCO.sub.3(50 mL). To the
organic layer was added water (100 mL) and solid sodium bisulfite
(20 eq). The organic layer was washed with brine and dried over
anhydrous Na.sub.2SO.sub.4. The solution was then concentrated and
purified by column chromatography over silica gel using gradient
elution 100%/cyclohexane to 50% ethyl acetate/cyclohexane to give
0.87 g of pure product in 50% yield.
[0122] Spiro lactam Intermediates 5 (AK-51). 0.5 g of 4 were
dissolved in 20 mL of ethyl acetate and transferred via cannula to
a flask under H2 (1 atm) containing 50 mg of 10% Pd(OH).sub.2--C
catalyst. The mixture was stirred for overnight under H.sub.2 at 50
PSi and then the catalyst was filtered off through celite. The
organic layer was concentrated and purified by chromatography on
silica gel to afford 120 mg of product in 50% yield.
[0123] N-(Cbz)-O-(benzyl ether)-L-threonine acid chloride 7. To a
stirred solution of N-(Cbz)-O-(benzyl ether)-L-threonine (0.95 g,
2.7 mmol.) in dry ether (27 mL) was added PCl5 (0.61 g, 2.9 mmol.)
and the mixture was stirred for 3 hours at room temperature. Then
the solvent was removed with high vacuum at room temperature.
Toluene was added and removed as above. The crude white solid was
used without any purification for the coupling reaction.
[0124] Spiro lactams Intermediates 8 and 9. To a stirred solution
of spiro lactam 4 (200 mg, 0.76 mmol.) in dry THF (4 mL) at
-78.degree. C. was added BuLi (0.32 mL, 0.80 mmol. in hexane)
dropwise. After addition was complete, the mixture was stirred at
-78.degree. C. for 1 hour. N-(Cbz)-O-(benzyl ether)-L-threonine
acid chloride 7 in THF (4 mL) was added at -78.degree. C. The
mixture was stirred for overnight from -78.degree. C. to room
temperature.
[0125] The reaction mixture was quenched with saturated NH.sub.4Cl
(10 mL) and ethyl acetate (10 mL) was added. The water layer was
extracted twice with ethyl acetate. The combined organic layers
were dried with MgSO.sub.4 and concentrated to give 0.44 g of crude
product. The crude product was eluted through silica gel with a
gradient from 100% CH.sub.2Cl.sub.2 to 2% MeOH/CH.sub.2Cl.sub.2
giving fractions that ranged in purity from 44% to 73%. This
reaction was repeated on 0.28 g of spiro lactam 4 and gave after
chromatography fractions with purities that ranged from 50% to
73%.
Example 4
NMDA Receptor Binding Assay
Tissue Preparation:
[0126] Crude synaptic membranes were prepared from rat hippocampi
or from rat forebrains (male Sprague-Dawley rats) and washed
extensively to remove endogenous amino acids, as previously
described by Ransom and Stec (1988). Briefly, the crude synaptic
membranes were resuspended in 20 volumes of 5 mM Tris-HCl buffer,
pH 7.4 (for use in [.sup.3H]TCP-binding experiments), or in 20
volumes of 5 mM Tris-acetate buffer, pH 7.4 (for use in
[.sup.3H]glycine-binding studies) and homogenized using a Polytron
(Virtis shear; Virtis, N.Y., U.S.A.). Membranes were then pelleted
by centrifugation at 48,000 g for 20 min. This step was repeated
twice and the homogenate was stored at -70.degree. C. in the same
buffer. Before each use, homogenates were thawed at room
temperature, pelleted, and washed four additional times. For the
[.sup.3H]glycine experiment, the pellet was first incubated for 30
min at 25.degree. C. in 5 mM Tris-acetate buffer containing 0.04%
Triton X-100 and then washed four times by homogenization and
centrifugation. The final washed membranes were resuspended at
concentrations of 2-3 mg/ml in either 5 mM Tris-HCl buffer or 5 mM
Tris-acetate buffer.
[0127] TCP binding assays: Measurements of specific [.sup.3H]TCP
binding were performed as described previously (Haring et al.,
1986, 1987; Kloog et al., 1988a). Final reaction mixtures consisted
of 50-100 .mu.g of membrane protein in 200 .mu.l of 5 mM Tris-HCI
buffer and contained either [.sup.3H]TCP, or [.sup.3H]TCP and the
appropriate concentration of NMDA-receptor ligands or mAbs.
Reactions were initiated by the addition of the membranes to the
reaction mixtures. Unless otherwise indicated, binding assays were
performed under nonequilibrium conditions at 25.degree. C. for 1 h.
Nonspecific binding was determined in parallel samples containing
100 .mu.M unlabeled PCP. Binding reactions were determined by
filtration on Whatman GF/B glass filters that had been pretreated
with 0.1% polyethyleneimine for 1 h.
[0128] The dissociation of [.sup.3H]TCP from its membrane-binding
site was measured after equilibrating the receptors with 20 nM
[.sup.3H]TCP for 120 min. The dissociation reaction was initiated
by the addition of 100 .mu.M unlabeled PCP in the presence and
absence of NMDA-receptor ligands or mAb. Reactions were terminated
immediately (zero time) and after incubation for the additional
periods of time indicated.
[0129] The effects of the three compounds were examined on 1) NMDA
receptor-gated single neuron conductance (I.sub.NMDA) in
hippocampal CAI pyramidal neurons and 2) the magnitude of long-term
potentiation (LTP) and long term depression(LTD) at Schaffer
collateral CA1 synapses, in in vitro hippocampal slices. GLYX-13
has been reported to exibit a low concentration (1-10 .mu.M)
enhancement of burst-activated I.sub.NMDA and LTP, while
simultaneously reducing LTD and single pulse evoked I.sub.NMDA. A
hundred fold higher GLYX-13 concentration of 100 .mu.M converted to
reducing LTP and burst I.sub.NMDA, and no longer affected LTD.
[0130] Compound B showed a 20-fold enhancement in potency compared
to GLYX-13. 50 nM of this compound markedly enhanced both single
shock (1A) and burst evoked (1B) I.sub.NMDA, as well as doubling
the magnitude of LTP (1E). In contrast, 1 .mu.M NRX-10,050
significantly reduced both single shock (1C) and burst evoked ((ID)
I.sub.NMDA, reminiscent of 100 .mu.M GLYX-13. (See FIG. 2).
[0131] AK-51 exhibited less potency than compound B, but a wider
concentration range in its stimulatory actions (FIG. 3). Both 100
nM (2A) and 1 .mu.M NRX-10,051 enhanced single-shock evoked
I.sub.NMDA, while 1 uM NRX-10,051 doubled the magnitude of LTP
(2D), while not altering LTD (2E).
[0132] AK-52 produced only a mild enhancement of single-shock
evoked I.sub.NMDA at a low concentration (100 nM; 3A), which
converted to significant reduction in I.sub.NMDA at a 1 uM
concentration (3B). 100 nM AK-52 produced an enhancement of LTP
similar in magnitude to compound B and AK-51, but this converted to
a slight, but significant, reduction in LTP at the 1 .mu.M
concentration, without altering LTD.
[0133] These three compound showed about a 20-fold enhancement in
potency compared to GLYX-13. Compound B is the most potent enhancer
of I.sub.NMDA at low concentrations (50 nM). While AK-51
enhancement of I.sub.NMDA was smaller in magnitude, this effect
remained when the AK-51 was increased 10-fold (100 nM to 1 .mu.M).
The AK-52 was the weakest enhancer of I.sub.NMDA, and this effect
reversed more quickly to a frank reduction in I.sub.NMDA.
[0134] These compounds enhanced the magnitude of LTP to similar
extents, approximately to a doubling. GLYX-13 was the only compound
that could simultaneously increase LTP and reduce LTD: AK-52 did
not affect LTD, even at a concentration that reduced I.sub.NMDA.
GLYX-13 can selectively enhance I.sub.NMDA mediated by NMDA
receptors containing NR2A/B subunits, and these receptors are
localized to extrasynaptic loci and are more strongly activated by
neuronal bursts that induce LTP. While all of the tested compounds
have potent effects on LTP and I.sub.NMDA, the lesser effects on
LTD suggest that they have increased selectivity for NR2A/B
containing NMDA receptor glycine sites than the GLYX-13.
Example 5
T-Maze Learning Model
[0135] Male 3 month old Fisher 344 X Brown Norway F1 cross rats
(FBNF1) were used for this study. The t-maze was constructed with
arms (45 cm long.times.10 cm wide.times.10 cm high) made of black
Plexiglas enclosing the maze. Two plastic bottle caps, lined with
wire mesh, were secured to the end of each goal arm in which the
food reward (Cheerios, 100 mg/piece) was placed. Before the start
of training, animals were gradually deprived of food to
approximately 85% of their free feeding weight. On three successive
days before the start of training, animals were habituated to the
t-maze with food located throughout the maze. On the first day of
training, animals were rewarded for right arm choices and were
trained to a criterion of 9 out of 10 consecutive correct choices.
On the second day of training, animals were rewarded for left arm
choices, and were trained to a criterion of 9 out of 10 consecutive
correct choices. On the subsequent testing day, animals were given
injections of AK51(0.3,1,3,10,30 mg/kg p.o.), or DMSO vehicle (1
mg/ml; Sigma, Saint Louis Mo.) in a blind manner via gastric gavage
(4'', 16-ga; Braintree Scientific, Braintree Mass.) 60 min prior to
the start of testing (n=8-9 per group. On the first trial of
testing, both arms were baited with food and for the subsequent 20
trials only alternating choices (opposite of the animal's previous
choice) were rewarded (.about.30 sec inter-trial interval). The
number of trials to criterion (5 consecutive correct choices) was
calculated for each animal. Data was analyzed by ANOVA followed by
Fisher PLSD post hoc tests comparing individual drug doses to
vehicle (.alpha.=0.05).
[0136] FIG. 5 depicts mean (.+-.SEM) trials to criterion in the
alternating T-maze task (20 trials) in food deprived 3 month old
rats. Animals were injected p.o. with 0, 0.3, 1, 3, 10, or 30 mg/kg
AK051 in DMSO vehicle (n=8-9 per group) 60 min before the start of
testing. ***P<0.001, **P<0.01, Fisher PLSD post hoc vs.
vehicle
Example 6
Formalin Test of Neuropathic Pain
[0137] Experiments were conducted as previously described (Abbott
et al. Pain, 60, 91-102, 1995; Wood et al., Neuroreport, 19,
1059-1061 2008). Male 3 month old Fisher 344 X Brown Norway F1
cross rats (FBNF1) were used for this study. Before the start of
testing, animals were habituated to the testing chamber
(30.times.30.times.60 cm opaque plexiglass) for 10 min each day
over 2 consecutive days. On the testing day, animals were given
injections of AK51 (0.3,1,3,10,30 mg/kg p.o.), or DMSO vehicle (1
mg/ml; Sigma, Saint Louis Mo.) in a blind manner via gastric gavage
(4'', 16-ga; Braintree Scientific, Braintree Mass.) 60 min prior to
formalin injections (n=8-9 per group). Animals were placed into the
testing chamber 10 min prior to formalin injection. For the
formalin injection, rats were manually restrained and given a
subcutaneous injection of 1.5% formalin (50 .mu.L with a 26-ga
needle; Sigma, Saint Louis Mo.) into the lateral footpad on the
plantar surface of the left hind paw. After formalin injections
rats were placed back into the testing chambers. Animals were
videotaped from below with the aid of an angled mirror for 50 min
post formalin injection. Total time spent licking the injected paw
and total number of injected paw flinches during the late phase
(30-50 min post formalin injection) were quantified off-line in a
blind manner by a trained experimenter with high (r>0.9) inter-
and intra-rater reliability for both measures. All animals were
euthanized by CO.sub.2 immediately after testing. Data was analyzed
by ANOVA followed by Fisher PLSD post hoc tests comparing
individual drug doses to vehicle (.alpha.=0.05). FIG. 6 depicts
mean (.+-.SEM) % Analgesia defined as % reduction in flinches in
the late phase response (30-50 min) after intraplantar formalin
injection (50 .mu.L of 1.5% formalin).
Example 7
Oral Formulations Enhancing Learning and Memory
[0138] An oral preparation of AK-51, was prepared in
dimethylsulfoxide (DMSO). All doses were administered in a volume
of 300 .mu.l. The animals were then fed p.o. by gavage (force fed
by mouth with an inserted feeding needle) a volume calculated to
deliver to the animal a defined dose based on body weight as
follows 0.0 mg/kg300 .mu.L DMSO (vehicle); 0.3 mg/kg, 300 .mu.L in
DMSO; 1.0 mg/kg, 300 .mu.L in DMSO; 3.0 mg/kg, 300 .mu.L in DMSO;
10.0 mg/kg, 300 .mu.L in DMSO; 30.0 mg/kg, 300 .mu.L in DMSO.
[0139] Animals were injected 60 minutes before the start of testing
with one of the dose amounts recited above. Then, an alternating
T-maze task (20 trials) was used to access learning behavior in the
animals. This protocol is described at Example 5. Briefly, the
T-maze is a choice task. The subject rat was placed in the base of
the "T". Following a short delay, it was allowed to explore the
maze and choose to enter either the right or left arms. The choice
is scored according to variety of criterion, including spontaneous
alternation, cued reward, or to indicate a preference. Based on the
criterion used in this study, the T-maze was used to test learning
and memory. Food placed at one end of the maze was used as the
positive reinforcer for each animal test.
[0140] Animals given a 1.0 mg/kg dose by mouth of AK-51
demonstrated a statistically significant enhancement of learning
behavior in the T-maze test (P<0.001). Animals given a 3.0 mg/kg
dose by mouth of the non-peptide analog NRX-10,051 also
demonstrated a statistically significant enhancement of learning
behavior in the T-maze test (P<0.01).
Example 8
Isomers
[0141] The two different isomers of AK-55 was used in a NDMA
binding assay as in Example 4. One isomer of AK-55 potently
enhances NMDA while the other does not. FIG. 7A indicates the time
course of effect of 15 min bath application of 1 .mu.M AK55 (solid
bar) on normalized pharmacologically-isolated NMDA receptor-gated
current in CA1 pyramidal neurons under whole-cell recording
(mean.+-.SEM, n=6). B: Time course of effect of 15 min bath
application of 1 .mu.M AK55 (solid bar) on normalized
pharmacologically-isolated NMDA receptor-gated current in CA1
pyramidal neurons under whole-cell recording (mean.+-.SEM, n=7). C:
Time course of effect of bath application of 1 .mu.M AK6 (solid
bar, filled circles, n=8) compared to untreated control slices
(open circles, n=8) on the magnitude of long-term potentiation
(LTP) of extracellular excitatory postsynaptic potential slope
(mean.+-.SEM fEPSP) induced by high-frequency Schaffer collateral
stimulation (2.times.100 Hz/500 msec).
Example 9
Biochemical Assays
[0142] Table B depicts the results of binding assays against
various targets with AK51:
TABLE-US-00002 TABLE B Target Species Concentration % Inhibition
Glutamate, AMPA rat 10 .mu.M -8 Glutamate, Kainate rat 10 .mu.M -13
Glutamate, Metabotropic, mGlu.sub.s human 10 .mu.M -7 Glutamate,
NMDA, Agonism rat 10 .mu.M 27 Glutamate, NMDA, Glycine rat 10 .mu.M
-6 Glutamate, NMDA, rat 10 .mu.M -5 Phencyclidine Glutamate, NMDA,
Polyamine rat 10 .mu.M -14 Glutamate, Non-Selective rat 10 .mu.M
-10 Glycine, Strychnine-Sensitive rat 10 .mu.M 4 Potassium Channel
hERG human 10 .mu.M 3
Equivalents
[0143] Those skilled in the art will recognize, or be able to
ascertain using no more than routine experimentation, many
equivalents to the specific embodiments of the invention described
herein. Such equivalents are intended to be encompassed by the
following claims.
Incorporation by Reference
[0144] The entire contents of all patents, published patent
applications, websites, and other references cited herein are
hereby expressly incorporated herein in their entireties by
reference.
* * * * *