U.S. patent application number 10/109095 was filed with the patent office on 2006-05-11 for 5-beta-sapogenin and pseudosapogenin derivatives and their use in the treatment of dementia.
Invention is credited to Paul Barraclough, Phil Gunning, Jim Hanson, Yaer Hu, Daryl Rees, Zongqin Xia.
Application Number | 20060100184 10/109095 |
Document ID | / |
Family ID | 10861837 |
Filed Date | 2006-05-11 |
United States Patent
Application |
20060100184 |
Kind Code |
A9 |
Barraclough; Paul ; et
al. |
May 11, 2006 |
5-beta-sapogenin and pseudosapogenin derivatives and their use in
the treatment of dementia
Abstract
The invention discloses the use of sapogenin derivatives in the
treatment of cognitive disfunction and similar conditions. Methods
of treatment and pharmaceutical compositions are also disclosed
Inventors: |
Barraclough; Paul;
(Maidstone, GB) ; Hanson; Jim; (West Sussex,
GB) ; Gunning; Phil; (Cambs, GB) ; Rees;
Daryl; (Sandy, GB) ; Xia; Zongqin; (Shanghai,
CN) ; Hu; Yaer; (Shanghai, CN) |
Correspondence
Address: |
Carl E. Moore, Jr.;MARSHALL, GERSTEIN & BORUN
6300 Sears Tower
233 South Wacker Drive
Chicago
IL
60606-6402
US
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20030004147 A1 |
January 2, 2003 |
|
|
Family ID: |
10861837 |
Appl. No.: |
10/109095 |
Filed: |
March 28, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/GB00/03737 |
Sep 29, 2000 |
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10109095 |
Mar 28, 2002 |
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09647110 |
Jan 11, 2001 |
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PCT/GB99/00951 |
Mar 26, 1999 |
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PCT/GB00/03737 |
Sep 29, 2000 |
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Current U.S.
Class: |
514/172 ;
514/173 |
Current CPC
Class: |
A61P 25/14 20180101;
C07J 71/00 20130101; C07J 71/0005 20130101; A61P 25/16 20180101;
A61P 25/00 20180101; A61P 43/00 20180101; A61P 25/28 20180101; A61P
21/04 20180101; A61P 9/02 20180101 |
Class at
Publication: |
514/172 ;
514/173 |
International
Class: |
A61K 31/58 20060101
A61K031/58 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 1999 |
GB |
9923076.5 |
Claims
1. A method of treating or preventing cognitive dysfunction in a
human or non-human animal suffering therefrom or susceptible
thereto, which comprises administering to the said human or
non-human animal an effective amount of a ##STR34## sapogenin or
sapogenin derivative of general formula (I) or (II): including all
stereoisomers and racemic mixtures thereof, or a pharmaceutically
acceptable pro-drug or salt thereof, wherein: in the general
formula (I): R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6,
R.sub.7, R.sub.8, R.sub.10, are, independently of each other,
either H, OH, .dbd.O, and OR where R=optionally substituted alkyl,
optionally substituted acyl, carbamoyl, alkoxycarbonyl; R.sub.9,
R.sub.12, R.sub.11, R.sub.13 can be either a H, OH, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.14=optionally substituted alkyl
group ..... represents an optional double bond, but excluding where
simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, R.sub.3.dbd..beta.OH, R.sub.14.dbd.CH.sub.3 the methyl group at
C22 is .alpha., the double bonds are absent the C20 is .alpha., and
there is a S configuration at C25; and wherein in the general
formula (II): R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6,
R.sub.7, R.sub.8, R.sub.10, are, independently of each other,
either H, OH, .dbd.O, or OR where R=optionally substituted alkyl,
optionally substituted acyl, carbamoyl, alkoxycarbonyl; R.sub.9,
R.sub.12, R.sub.11, R.sub.13 can be either a H, OH, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.14=optionally substituted alkyl
group; R.sub.15=H, optionally substituted alkyl, optionally
substituted acyl, or glucosyl; ..... represents an optional double
bond; and where a pro-drug is used, it comprises a compound in
which one or more of the above defined variable groups carries a
moiety which is hydrolysed off in vivo to provide the compound of
general formula (I) or (II).
2. A method according to claim 1, wherein in the general formula
(I) there is further excluded the compound where simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, R.sub.3.dbd..beta.OH, R.sub.14.dbd.CH.sub.3 the methyl group at
C22 is .alpha., the double bonds are absent the C20 is .alpha., and
there is a R configuration at C25; and the compound where
simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, R.sub.3.dbd..beta.--OCOCH.sub.2CH.sub.2COOH
R.sub.14.dbd.CH.sub.3 the methyl group at C22 is .alpha., the
double bonds are absent the C20 is .alpha., and there is a S
configuration at C25.
3. A method according to claim 1, wherein in the general formula
(I) R.sub.4, R.sub.9, R.sub.12, R.sub.13.dbd.H R.sub.1, R.sub.2,
R.sub.3, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.10, are
independently of each other either H, OH, .dbd.O, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.11.dbd.H, OH, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.14=alkyl group and .....
represents an optional double bond.
4. A method according to claim 1, wherein in the general formula
(I):
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, R.sub.3.dbd.H, --OH, --OMe, --OCOCH.sub.3, .dbd.O,
--O--CO.sub.2Et, --O--CO--(CH.sub.2).sub.2--CO.sub.2H;
R.sub.14=CH.sub.3.
5. A method according to claim 1, wherein in the general formula
(II): R.sub.4, R.sub.9, R.sub.12, R.sub.13.dbd.H R.sub.1, R.sub.2,
R.sub.3, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.10, can be
independently of each other either H, OH, .dbd.O, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.11.dbd.H, OH, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.14=optionally substituted alkyl
group R.sub.15.dbd.H, optionally substituted alkyl, optionally
substituted acyl, or glucosyl; and ..... represents an optional
double bond.
6. A method according to claim 1, wherein the compound is selected
from 3-methoxy-sarsasapogenin, 3-methoxy-epismilagenin, smilagenin
cathylate epismilagenin succinate, epismilagenin, sarsasapogenin
acetate, smilgenin acetate, epismilagenin acetate, smilagenone, and
derivatives of smilagenin and sarsasapogenin in which there is no
substituent at C3 and there is a single bond between C2 and C3 and
between C3 and C4 or there is a double bond between C2 and C3 or
between C3 and C4.
7. A method according to claim 1, wherein said human or non-human
animal is suffering from age-related cognitive dysfunction.
8. A method according to claim 1, for treating a disease selected
from: Alzheimer's disease, senile dementia of the Alzheimer's type,
Parkinson's disease, Lewi body dementia, postural hypotension,
autism, chronic fatigue syndrome, Myasthenia Gravis, Lambert Eaton
disease, and problems associated with ageing.
9. A method according to claim 1, for treating a disease selected
from Alzheimer's disease or senile dementia of the Azheimer's
type.
10. A method according to claim 1, wherein the compound of formula
(I) or (II) or a pro-drug or salt thereof is administered in the
form of a pharmaceutical composition, foodstuff, food supplement or
beverage.
11. A non-therapeutic method of enhancing cognitive function in a
human or non-human animal, which comprises administering to the
said human or non-human animal an effective dose of a compound of
formula (I) or (II) or a pro-drug or salt thereof as defined in
claim 1.
12. A method according to claim 10, wherein the compound of formula
(I) or (II) or a pro-drug or salt thereof is administered in the
form of a foodstuff, food supplement or beverage.
13. A pharmaceutical composition having cognitive function
enhancing properties, which comprises a physiologically effective
amount of a compound of formula (I) or (II) or a pro-drug or salt
thereof as defined in claim 1, in association with one or more
pharmaceutically acceptable carrier, diluent or excipient.
14. A foodstuff, food supplement or beverage having cognitive
function enhancing properties, which comprises a physiologically
effective amount of a compound of formula (I) or (II) or a pro-drug
or salt thereof as defined in claim 1, in association with an
edible carrier, diluent or excipient.
15. A pharmaceutical composition according to claim 12, wherein the
compound of formula (I) or (II) or pro-drug or salt thereof is in
the form of an extract derived from a plant of the genus Smilax,
Asparagus, Anemarrhena, Yucca or Agave.
16. A foodstuff, food supplement or beverage according to claim 13,
wherein the compound of formula (I) or (II) or pro-drug or salt
thereof is in the form of an extract derived from a plant of the
genus Smilax, Asparagus, Anemarrhena, Yucca or Agave.
17. A method of increasing the muscarinic, nicotinic or dopamine
receptor number or enhancing the function of muscarinic, nicotinic
or dopamine receptors in the said human or non-human animal in need
thereof, which comprises administering to the said human or
non-human animal an effective amount of a sapogenin or ##STR35##
sapogenin derivative of general formula (I) or (II): including all
stereoisomers and racemic mixtures thereof, or a pharmaceutically
acceptable pro-drug or salt thereof, wherein: in the general
formula (I): R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6,
R.sub.7, R.sub.8, R.sub.10, are, independently of each other,
either H, OH, .dbd.O, and OR where R=optionally substituted alkyl,
optionally substituted acyl, carbamoyl, alkoxycarbonyl; R.sub.9,
R.sub.12, R.sub.11, R.sub.13 can be either a H, OH, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.14=optionally substituted alkyl
group ..... represents an optional double bond, but excluding where
simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, R.sub.3.dbd..beta.OH, R.sub.14.dbd.CH.sub.3 the methyl group at
C22 is .alpha., the double bonds are absent the C20 is .alpha., and
there is a S configuration at C25; and wherein in the general
formula (II): R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6,
R.sub.7, R.sub.8, R.sub.10, are, independently of each other,
either H, OH, .dbd.O, or OR where R=optionally substituted alkyl,
optionally substituted acyl, carbamoyl, alkoxycarbonyl;
R.sub.9R.sub.12, R.sub.11, R.sub.13 can be either a H, OH, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.14=optionally substituted alkyl
group; R.sub.15=H, optionally substituted alkyl, optionally
substituted acyl, or glucosyl; ..... represents an optional double
bond; and where a pro-drug is used, it comprises a compound in
which one or more of the above defined variable groups carries a
moiety which is hydrolysed off in vivo to provide the compound of
general formula (I) or (II).
18. A method according to claim 17, wherein in the general formula
(I) there is further excluded the compound where simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, R.sub.3.dbd..beta.OH, R.sub.14.dbd.CH.sub.3 the methyl group at
C22 is .alpha., the double bonds are absent the C20 is .alpha., and
there is a R configuration at C25; and the compound where
simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, R.sub.3.dbd..beta.--OCOCH.sub.2CH.sub.2COOH
R.sub.14.dbd.CH.sub.3 the methyl group at C22 is .alpha., the
double bonds are absent the C20 is .alpha., and there is a S
configuration at C25.
19. A method according to claim 17, wherein in the general formula
(I): R.sub.4, R.sub.9, R.sub.12, R.sub.13.dbd.H R.sub.1, R.sub.2,
R.sub.3, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.10, are
independently of each other either H, OH, .dbd.O, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.11.dbd.H, OH, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.14=alkyl group and .....
represents an optional double bond.
20. A method according to claim 17, wherein in the general formula
(I):
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, R.sub.3.dbd.H, --OH, --OMe, --OCOCH.sub.3, .dbd.O,
--O--CO.sub.2Et, --O--CO--(CH.sub.2).sub.2--CO.sub.2H;
R.sub.14.dbd.CH.sub.3.
21. A method according to claim 17, wherein in the general formula
(II): R.sub.4, R.sub.9, R.sub.12, R.sub.13.dbd.H R.sub.1, R.sub.2,
R.sub.3, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.10, can be
independently of each other either H, OH, .dbd.O, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.11.dbd.H, OH, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.14=optionally substituted alkyl
group R.sub.15=H, optionally substituted alkyl, optionally
substituted acyl, or glucosyl; and ..... represents an optional
double bond.
22. A method according to claim 17, wherein the compound is
selected from 3-methoxy-sarsasapogenin, 3-methoxy-epismilagenin,
smilagenin cathylate epismilagenin succinate, epismilagenin,
sarsasapogenin acetate, smilgenin acetate, epismilagenin acetate,
smilagenone, and derivatives of smilagenin and sarsasapogenin in
which there is no substituent at C3 and there is a single bond
between C2 and C3 and between C3 and C4 or there is a double bond
between C2 and C3 or between C3 and C4.
23. A method according to claim 17, wherein said human or non-human
animal is suffering from age-related cognitive dysfunction.
24. A method according to claim 17, wherein said human or non-human
animal is suffering from a disease selected from: Alzheimer's
disease, senile dementia of the Alzheimer's type, Parkinson's
disease, Lewi body dementia, postural hypotension, autism, chronic
fatigue syndrome, Myasthenia Gravis, Lambert Eaton disease, and
problems associated with ageing.
25. A method according to claim 17, wherein said human or non-human
animal is suffering from a disease selected from Alzheimer's
disease or senile dementia of the Alzheimer's type.
26. A method according to claim 17, wherein the compound of formula
(I) or (II) or a pro-drug or salt thereof is administered in the
form of a pharmaceutical composition, foodstuff, food supplement or
beverage.
27. A pharmaceutical composition having the capacity to increase
the muscarinic, nicotinic or dopamine receptor number or enhance
the function of muscarinic, nicotinic or dopamine receptors in a
human or non-human animal in need thereof, which comprises a
physiologically effective amount of a compound of formula (I) or
(II) or a pro-drug or salt thereof as defined in claim 1, in
association with one or more pharmaceutically acceptable carrier,
diluent or excipient.
28. A foodstuff, food supplement or beverage having the capacity to
increase the muscarinic, nicotinic or dopamine receptor number or
enhance the function of muscarinic, nicotinic or dopamine receptors
in a human or non-human animal in need thereof, which comprises a
physiologically effective amount of a compound of formula (I) or
(II) or a pro-drug or salt thereof as defined in claim 1, in
association with an edible carrier, diluent or excipient.
29. A pharmaceutical composition according to claim 27, wherein the
compound of formula (I) or (II) or pro-drug or salt thereof is in
the form of an extract derived from a plant of the genus Smilax,
Asparagus, Anemarrhena, Yucca or Agave.
30. A foodstuff, food supplement or beverage according to claim 28,
wherein the compound of formula (I) or (II) or pro-drug or salt
thereof is in the form of an extract derived from a plant of the
genus Smilax, Asparagus, Anemarrhena, Yucca or Agave.
31. A method of treating or preventing a condition characterized by
the presence of neurofibrillary tangles and/or .beta.-amyloid
plaques in a human or non-human animal suffering therefrom or
susceptible thereto, which comprises administering to the said
human or non-human animal an effective amount of a sapogenin or
sapogenin derivative of general formula (I) or (II) ##STR36##
including all stereoisomers and racemic mixtures thereof, or a
pharmaceutically acceptable pro-drug or salt thereof, wherein: in
the general formula (I): R.sub.1, R.sub.2, R.sub.3, R.sub.4,
R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.10, are, independently of
each other, either H, OH, .dbd.O, and OR where R=optionally
substituted alkyl, optionally substituted acyl, carbamoyl,
alkoxycarbonyl; R.sub.9, R.sub.12, R.sub.11, R.sub.13 can be either
a H, OH, OR where R=optionally substituted alkyl, optionally
substituted acyl, carbamoyl, alkoxycarbonyl; R.sub.14=optionally
substituted alkyl group ..... represents an optional double bond,
but excluding where simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, R.sub.3.dbd..beta.OH, R.sub.14.dbd.CH.sub.3 the methyl group at
C22 is .alpha., the double bonds are absent the C20 is .alpha., and
there is a S configuration at C25; and wherein in the general
formula (II): R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6,
R.sub.7, R.sub.8, R.sub.10, are, independently of each other,
either H, OH, .dbd.O, or OR where R=optionally substituted alkyl,
optionally substituted acyl, carbamoyl, alkoxycarbonyl; R.sub.9,
R.sub.12, R.sub.11, R.sub.13 can be either a H, OH, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.14=optionally substituted alkyl
group; R.sub.15=H, optionally substituted alkyl, optionally
substituted acyl, or glucosyl; ..... represents an optional double
bond; and where a pro-drug is used, it comprises a compound in
which one or more of the above defined variable groups carries a
moiety which is hydrolysed off in vivo to provide the compound of
general formula (I) or (II).
32. A method according to claim 31, wherein in the general formula
(I) there is further excluded the compound where simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, R.sub.3.dbd..beta.OH, R.sub.14.dbd.CH.sub.3 the methyl group at
C22 is .alpha., the double bonds are absent the C20 is .alpha., and
there is a R configuration at C25; and the compound where
simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, R.sub.3.dbd..beta.--OCOCH.sub.2CH.sub.2COOH
R.sub.14.dbd.CH.sub.3 the methyl group at C22 is .alpha., the
double bonds are absent the C20 is .alpha., and there is a S
configuration at C25.
33. A method according to claim 31, wherein in the general formula
(I): p1 R.sub.4, R.sub.9, R.sub.12, R.sub.13.dbd.H R.sub.1,
R.sub.2, R.sub.3, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.10, are
independently of each other either H, OH, .dbd.O, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.11.dbd.H, OH, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.14=alkyl group and .....
represents an optional double bond.
34. A method according to claim 31, wherein in the general formula
(I):
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.10.dbd.R.sub.11R.sub.9.dbd.R.sub.12.dbd.R.sub.13.dbd.H,
R.sub.3.dbd.H, --OH, --OMe, --OCOCH.sub.3, .dbd.O, --O--CO.sub.2Et,
--O--CO--(CH.sub.2).sub.2--CO.sub.2H; R.sub.14.dbd.CH.sub.3.
35. A method according to claim 31, wherein in the general formula
(II): R.sub.4, R.sub.9, R.sub.12, R.sub.13.dbd.H R.sub.1, R.sub.2,
R.sub.3, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.10, can be
independently of each other either H, OH, .dbd.O, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.11.dbd.H, OH, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.14=optionally substituted alkyl
group R.sub.15=H, optionally substituted alkyl, optionally
substituted acyl, or glucosyl; and ..... represents an optional
double bond.
36. A method according to claim 31, wherein the compound is
selected from 3-methoxy-sarsasapogenin, 3-methoxy-epismilagenin,
smilagenin cathylate epismilagenin succinate, epismilagenin,
sarsasapogenin acetate, smilgenin acetate, epismilagenin acetate,
smilagenone, and derivatives of smilagenin and sarsasapogenin in
which there is no substituent at C3 and there is a single bond
between C2 and C3 and between C3 and C4 or there is a double bond
between C2 and C3 or between C3 and C4.
37. A method according to claim 31, wherein said human or non-human
animal is suffering from age-related cognitive dysfunction.
38. A method according to claim 31, wherein said human or non-human
animal is suffering from a disease selected from: Alzheimer's
disease, senile dementia of the Alzheimer's type, Parkinson's
disease, Lewi body dementia, postural hypotension, autism, chronic
fatigue syndrome, Myasthenia Gravis, Lambert Eaton disease, and
problems associated with ageing.
39. A method according to claim 31, wherein said human or non-human
animal is suffering from a disease selected from Alzheimer's
disease or senile dementia of the Azheimer's type.
40. A method according to claim 32, wherein the compound of formula
(I) or (II) or a pro-drug or salt thereof is administered in the
form of a pharmaceutical composition, foodstuff, food supplement or
beverage.
41. A pharmaceutical composition having the capacity to alleviate
or treat a condition characterized by the presence of
neurofibrillary tangles and/or .beta.-amyloid plaques in a human or
non-human animal suffering therefrom or susceptible thereto, which
comprises a physiologically effective amount of a compound of
formula (I) or (II) or a pro-drug or salt thereof as defined in
claim 1, in association with one or more pharmaceutically
acceptable carrier, diluent or excipient.
42. A foodstuff, food supplement or beverage having the capacity to
alleviate or treat a condition characterized by the presence of
neurofibrillary tangles and/or .beta.-amyloid plaques in a human or
non-human animal suffering therefrom or susceptible thereto, which
comprises a physiologically effective amount of a compound of
formula (I) or (II) or a pro-drug or salt thereof as defined in
claim 1, in association with an edible carrier, diluent or
excipient.
43. A pharmaceutical composition according to claim 41, wherein the
compound of formula (I) or (II) or pro-drug or salt thereof is in
the form of an extract derived from a plant of the genus Smilax,
Asparagus, Anemarrhena, Yucca or Agave.
44. A foodstuff, food supplement or beverage according to claim 42,
wherein the compound of formula (I) or (II) or pro-drug or salt
thereof is in the form of an extract derived from a plant of the
genus Smilax, Asparagus, Anemarrhena, Yucca or Agave.
45. A compound which is a sapogenin or sapogenin derivative of
general ##STR37## formula (I) or (II): including all stereoisomers
and racemic mixtures thereof, or a pharmaceutically acceptable
pro-drug or salt thereof, wherein: in the general formula (I):
R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7,
R.sub.8, R.sub.10, are, independently of each other, either H, OH,
.dbd.O, and OR where R=optionally substituted alkyl, optionally
substituted acyl, carbamoyl, alkoxycarbonyl; R.sub.9, R.sub.12,
R.sub.11, R.sub.13 can be either a H, OH, OR where R=optionally
substituted alkyl, optionally substituted acyl, carbamoyl,
alkoxycarbonyl; R.sub.14=optionally substituted alkyl group .....
represents an optional double bond, but excluding where
simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, R.sub.3.dbd..beta.OH, R.sub.14.dbd.CH.sub.3 the methyl group at
C22 is .alpha., the double bonds are absent the C20 is .alpha., and
there is a S configuration at C25; and excluding where
simultaneously:
R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.8.dbd.R.sub.9.dbd.R.sub.10.dbd.-
R.sub.11.dbd.R.sub.12R.sub.13.dbd.H, R.sub.3.dbd.OH, OCOCH.sub.3,
OCH.sub.3 or OCH.sub.2CH.sub.3 R.sub.14.dbd.CH.sub.3 the double
bonds are absent and either (i) R.sub.1.dbd.OH or H; (ii)
R.sub.2.dbd.OH or H; or (iii) R.sub.7.dbd.OH or H; and excluding
where simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.3.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R-
.sub.7.dbd.R.sub.8.dbd.R.sub.9.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.12.dbd.-
R.sub.13.dbd.H, there is a double bond between C2 and C3 or between
C3 and C4 R.sub.14.dbd.CH.sub.3; and excluding where
simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.9.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H R.sub.14.dbd.CH.sub.3 the stereochemistry of C25 is R and the
double bonds are absent R.sub.3.dbd..beta.OR, where OR=propionate,
butyrate, valerate, isovalerate, caproate, isocaproate,
diethylacetate, octanoate, decanoate, laurate, myristate,
palmitate, stearate, benzoate, phenylacetate, phenylpropionate,
cinnamate, p-nitrobenzoate, 3,5-dinitrobenzoate, p-chlorobenzoate,
2,4-dichlorobenzoate, p-bromobenzoate, m-bromobenzoate,
p-methoxybenzoate, benzenesulphonate, p-toluenesulphonate,
cyclopentylpropionate, furoate, sucinnate or phthalate; and
excluding where simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.9.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, R.sub.14.dbd.CH.sub.3 the stereochemistry of C25 is S and the
double bonds are absent R.sub.3.dbd..beta.OR, where OR=sucinnate;
and excluding where simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.9.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, R.sub.14.dbd.CH.sub.3 the double bonds are absent
R.sub.3.dbd.(.dbd.O); and wherein in the general formula (II):
R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7,
R.sub.8, R.sub.10, are, independently of each other, either H, OH,
.dbd.O, or OR where R=optionally substituted alkyl, optionally
substituted acyl, carbamoyl, alkoxycarbonyl; R.sub.9, R.sub.12,
R.sub.11, R.sub.13 can be either a H, OH, OR where R=optionally
substituted alkyl, optionally substituted acyl, carbamoyl,
alkoxycarbonyl; R.sub.14=optionally substituted alkyl group;
R.sub.15=H, optionally substituted alkyl, optionally substituted
acyl, or glucosyl; ..... represents an optional double bond; but
excluding where simultaneously:
R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.8.dbd.R.sub.9.dbd.R.sub.10.dbd.-
R.sub.11.dbd.R.sub.12.dbd.R.sub.13.dbd.H, R.sub.14.dbd.CH.sub.3
R.sub.15=H or glucose and the double bonds are absent and either
(i) R.sub.1.dbd.OH or H; (ii) R.sub.2.dbd.OH or H; or (iii)
R.sub.7.dbd.OH or H; and excluding where simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.8.dbd.R-
.sub.9.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.12.dbd.R.sub.13.dbd.H,
R.sub.14.dbd.CH.sub.3 R.sub.3.dbd.R.sub.15.dbd.OCOCH.sub.3 and the
double bonds are absent; and excluding where simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.9.dbd.R.sub.10.dbd.R.sub.11R.sub.12.dbd.R.sub.13.dbd.R.su-
b.15.dbd.H, R.sub.14.dbd.CH.sub.3 R.sub.3.dbd.(.dbd.O) and the
double bonds are absent; and excluding where simultaneously:
R.sub.1.dbd.R.sub.2.dbd.R.sub.3.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R-
.sub.7.dbd.R.sub.8.dbd.R.sub.9.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.12.dbd.-
R.sub.13.dbd.R.sub.15.dbd.H, R.sub.14.dbd.CH.sub.3 and there is a
double bond between C2 and C3 or between C3 and C4; and where the
compound is a pro-drug, it comprises a compound in which one or
more of the above defined variable groups carries a moiety which is
capable of being hydrolysed off in vivo to provide the compound of
general formula (I) or (II).
46. A compound according to claim 45, wherein in the general
formula (I): R.sub.4, R.sub.9, R.sub.12, R.sub.13.dbd.H R.sub.1,
R.sub.2, R.sub.3, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.10, are
independently of each other either H, OH, .dbd.O, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.11.dbd.H, OH, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.14=alkyl group and .....
represents an optional double bond.
47. A compound according to claim 45, wherein in the general
formula (I):
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.-
R.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.sub.13.db-
d.H, R.sub.3.dbd.H, --OH, --OMe, --OCOCH.sub.3, .dbd.O,
--O--CO.sub.2Et, --O--CO--(CH.sub.2).sub.2--CO.sub.2H;
R.sub.14.dbd.CH.sub.3.
48. A compound according to claim 45, wherein in the general
formula (II): R.sub.4, R.sub.9, R.sub.12, R.sub.13.dbd.H R.sub.1,
R.sub.2, R.sub.3, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.10, can
be independently of each other either H, OH, .dbd.O, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.11.dbd.H, OH, OR where
R=optionally substituted alkyl, optionally substituted acyl,
carbamoyl, alkoxycarbonyl; R.sub.14=optionally substituted alkyl
group R.sub.15=H, optionally substituted alkyl, optionally
substituted acyl, or glucosyl; and ..... represents an optional
double bond.
49. A compound selected from 3-methoxy-sarsasapogenin,
3-methoxy-epismilagenin, smilagenin cathylate and epismilagenin
succinate.
50. A pharmaceutical composition which comprises a compound of
formula (I) or (II) or a pro-drug or salt thereof as claimed in
claim 45, in association with one or more pharmaceutically
acceptable carrier, diluent or excipient.
51. A foodstuff, food supplement or beverage which comprises a
compound of formula (I) or (II) or a pro-drug or salt thereof as
defined in claim 45, in association with an edible carrier, diluent
or excipient.
Description
[0001] The present invention relates to sapogenin derivatives and
their use in treating cognitive disfunction and allied conditions;
and to compositions for use in such treatments. The invention is
also concerned with the treatment of conditions that are
characterised by a deficiency in the number or function of
membrane-bound receptors. In the following, the present invention
will be described principally with reference to the treatment of
Alzheimer's disease (AD) and senile dementia of the Alzheimer's
type (SDAT), where deficiencies in a number of receptor types have
been demonstrated. However, it is to be understood that the present
invention relates generally to the treatment of conditions
attributable to intrinsic pathological conditions and/or exposure
to adverse environmental conditions these conditions being
characterised by a deficiency in the number or function of
membrane-bound receptors or a deficiency in transmission at the
junctions between neurones or at the junctions of neurones and
effector cells.
[0002] Conditions of the type mentioned above include Parkinson's
disease, Lewi body dementia, postural hypotension, autism, chronic
fatigue syndrome, Myasthenia Gravis, Lambert Eaton disease,
diseases and problems associated with Gulf War Syndrome,
occupational exposure to organophosphorus compounds and problems
associated with ageing.
[0003] Alzheimer's disease (AD) and senile dementia of the
Alzheimer's type (SDAT) are grave and growing problems in all
societies where, because of an increase in life expectancy and
control of adventitious disease, the demographic profile is
increasingly extending towards a more aged population. Agents which
can treat, or help in the management of, AD/SDAT are urgently
required.
[0004] Age-associated memory impairment (AAMI) is a characteristic
of older patients who, while being psychologically and physically
normal, complain of memory loss. It is a poorly defined syndrome,
but agents which are effective in treatment of AD/SDAT may also be
of value in these patients.
[0005] Research into AD/SDAT is being carried out by traditional
and conventional medical research methods and disciplines. In
conventional medicine, there are several approaches to the
treatment of AD/SDAT. It is known that the biochemical processes
subserving memory in the cerebral cortex are (at least in part)
cholinergically-mediated. Those skilled in the art will know that
"cholinergically mediated" mechanisms may be directly attributable
to acetylcholine acting on receptors, and these are direct effects.
Other, clinically useful effects may also be caused by modulation
of release of acetylcholine from pre-synaptic nerve endings or
inhibition of enzymes that destroy acetylcholine. These modulating
factors may be exerted through neurones where the mediator is
non-cholinergic; these are referred to as indirect effects. Some
attempts at treatment have focussed on the role of other mediators
such as 5-hydroxytryptamine, which is a mediator in other areas of
brain, such as the mid-brain nuclei. However, since fibres from
these areas are projected forward into the cerebral cortex where
the primary transmitter is acetylcholine, attention has focussed on
the management of this mediator in the search for appropriate
therapeutic agents.
[0006] Cholinergic strategies for the treatment of AD/SDAT have
been directed at several points along the pathway of formation,
synaptic release and removal of released acetylcholine.
[0007] One approach involves treatment with high doses of lecithin
and other precursors of acetylcholine. This is of limited use in
producing sustained improvements in cognitive performance.
[0008] Another approach involves the use of vegetable drugs such as
Polygalae root extract, which has been shown to enhance
choline-acetylcholine transferase (CAT) activity and nerve growth
factor (NGF) secretion in brain. Oral administration of NGF has no
effect on central nervous system neurons because it is a high
molecular weight protein that cannot pass through the blood-brain
barrier. However, agents which can pass through the blood-brain
barrier and have a stimulating effect on NGF synthesis in the
central nervous system have been proposed for the improvement of
memory-related behaviour.
[0009] The results of a third clinical approach, which uses
cholinesterase inhibitors such as tacrine hydrochloride, have been
marginally more positive than the above. Substances obtained from
plants used in Chinese and Western medicine, for example huperzine,
galanthamine, and physostigmine have all been shown to be of
some--although limited--benefit in the treatment of AD/SDAT in
clinical studies and also in laboratory models. All of these
substances are inhibitors of acetylcholine esterase (AChE). In
patients with AD/SDAT, there may be reduced synthesis of
acetylcholine (ACh), reduced efficiency in release of ACh from
presynaptic stores, and a decrease in the number or function of
postsynaptic (M.sub.1) receptors. Reductions in pre-synaptic
M.sub.2 receptors have also been shown. The beneficial effect of
AChE inhibitors is attributed to enhancement of acetylcholine
levels at synapses in brain by slowing down the destruction of
released transmitter.
[0010] Compositions which modulate cholinergic function are known
to affect memory and recall. For example, nicotine stimulates
nicotinic acetylcholine receptors, and the short lived memory
enhancing effects of cigarette smoking are thought to be due to the
effect of nicotine. Scopolamine, an antagonist of acetylcholine,
will produce amnesia and impaired cognitive function manifesting in
psychomotor tests as a prolongation of simple reaction times,
possibly as a result of impaired attention, and is used for this
purpose as an adjunctive analgesic treatment. The amnesic effect of
scopolamine can be antagonised by nicotine.
[0011] There are two families of nicotinic receptor subtypes
(.alpha. and .beta.), and each includes four subgroups which differ
in ligand specificity. The role of nicotinic receptors in the CNS
is not well understood at the molecular level. It is possible that
agents binding to nicotinic receptors may modify the rate of
turnover at muscarinic receptor sites in brain. Nicotinic receptors
are ligand-gated ion channels, and their activation causes a rapid
(millisecond) increase in cellular permeability to Na.sup.+ and
Ca.sup.++, depolarisation and excitation.
[0012] Another class of cholinergic receptors can be stimulated by
muscarine. Such muscarinic (M) receptors are G protein-coupled
receptors. Responses of muscarinic receptors are slower; they may
be excitatory or inhibitory. They are not necessarily linked to
changes in ion permeability. Five types of muscarinic receptors
have been detected by cholinergic receptor cloning, and are
designated as m.sub.1-m.sub.5. Pharmacological effects are
associated with four of the cloned receptors and they are
designated as M.sub.1-M.sub.4 based on pharmacological
specificity.
[0013] Using specific receptor proteins and monoclonal antibodies,
it has been possible to further localise muscarinic receptors in
brain as m.sub.1 (postsynaptic) and m.sub.2 (presynaptic). In
heart, M.sub.2 receptors are postsynaptic. Presynaptic muscarinic
receptors are thought to be inhibitory, the binding of ACh to these
receptors attenuating the release of further ACh to provide a
negative feedback mechanism for Ach release. Selective M.sub.2
receptor antagonists which are preferentially distributed to the
brain may therefore be useful in treating Alzheimer's disease.
[0014] It is known that, in disease states such as AD/SDAT, there
is general neuronal loss and deficits in cholinergic nerve
function. It has been speculated that the high affinity nicotinic
binding sites in the remaining cholinergic neurons might be
converted to low affinity binding sites in treating such diseases,
thereby sustaining transmitter release. By lowering the affinity of
the nicotinic binding sites, a quick desensitising process is
avoided.
[0015] Agonist activation at nicotinic receptors in brain has rapid
onset and offset. A decreased affinity of the nicotinic receptors
will reduce the desensitisation process. Schwarz R. D. et al (J.
Neuro Chem 42, (1984), 1495-8) have shown that nicotine binding
sites are presynaptically located on cholinergic (and also
5-hydroxytryptaminergic and catecholaminergic) axon terminals. A
change in high affinity binding sites on AD/SDAT may also induce a
change in the modulatory effect the nicotinic binding sites may
have on other transmitter systems.
[0016] Presynaptic cholinergic mechanisms are also under inhibitory
control by GABAergic neurons and this inhibition is thought to be
intensified in AD/SDAT. Removal or reduction of this inhibition
intensifies presynaptic cortical cholinergic activity and enhances
cognitive processing.
[0017] The interactions of interneuronal fibres innervated by
nicotine (reducing binding affinity), and dis-inhibition of
GABAergic fibres both have a presynaptic locus.
[0018] This is a simplistic model of central transmission, but
provides a framework for understanding the attempts which have been
made to increase the effective concentration of acetylcholine in
central synapses. This further illustrates the concept of direct
and indirect action. There are disadvantages attaching to the three
conventional therapeutic approaches to AD/SDAT treatment mentioned
above: ACh precursor supplementation, agonist replacement and
acetylcholine esterase inhibition. These treatments may result in a
short-term increase in the availability of ACh which may activate
feedback mechanisms resulting in the desensitisation of
postsynaptic receptors. On theoretical grounds, long term benefits
would not be predicted and when treatment is interrupted, any
benefits in management of AD/SDAT and AAMI disappear and the
condition may even be aggravated.
[0019] It has been shown that a compound with M.sub.1 agonist and
M.sub.2/M.sub.3 antagonist activity improved cognitive performance
in SDAT patients (Sramak et al, Life Sciences vol. 2, No. 3,
195-202, 1997). However, this compound causes unacceptable
cholinergic side effects, such as fatigue, diarrhoea and
nausea.
[0020] A more radical approach to AD/SDAT and AAMI aims to increase
the number of postsynaptic (M.sub.1) receptors, in brain. It is
known from Chinese Patent No. CN1096031A, that sarsasapogenin (SaG)
can upregulate M.sub.1 cholinergic receptors.
[0021] Patent applications have been published which claim the
usefulness of a number of steroid sapogenins having spirostane,
furo-spirostane, spirosolane or solanidine structures in the
treatment of diseases including SDAT. Two patent publications are
of particular relevance here: Chinese patent publication No
CN1096031A claims the use of the spirostane sapogenin,
sarsasapogenin, in the treatment of SDAT. The disclosure in this
document, however, is brief. The other document of relevance is
patent publication DE 4303214A1 which claims the use of a very wide
range of saponins and sapogenins in the treatment of a whole range
of diseases that the inventors consider to be of viral origin. This
disclosure is however of dubious value in that it is well
recognised that there is no infective element to a very large
number of the conditions that are characterised by deficient
synaptic transmission and thus the basic premise of the alleged
invention is flawed. In addition they present no data of any kind
that allows one skilled in the art to be able select a preferred
compound from the large number that are claimed.
[0022] The inventors have found that certain sapogenin derivatives
exhibit the ability to regulate receptors. In particular, these
compounds have been found to increase the number of M2 receptors in
the brain. Thus, according to one aspect of the invention, there is
provided the use of a sapogenin derivative of general formula (I)
or (II) in the manufacture of a medicament for the treatment of a
condition characterised by a deficiency in membrane-bound receptor
number or function.
[0023] Those skilled in the art will be aware of the relationship
between saponins and their sapogenins, and that the latter tend to
be fat-soluble whereas the saponins tend to be water-soluble.
Sapogenins are therefore better able to cross the blood-brain
barrier. The skilled man will also be aware of the epimerisation of
certain sapogenins under conditions of acid hydrolysis.
[0024] The variation in pharmacological properties and
pharmacodynamic actions of various types of sapogenins underlines
the need for selection of those agents which are most useful in the
treatment or A/SDAT. The discovery of novel facts about the action
of sapogenin derivatives has made it possible to determine which
substances are most useful for the treatment for the treatment of
AD/SDAT and the like.
[0025] The inventors have found that the above-described properties
are exhibited by sapogenin derivatives wherein the A/B ring
conformation of the fused ring system is Cis.
[0026] Accordingly, the sapogenin derivatives of interest in this
invention have the following general formulas (I) or (II): ##STR1##
and their stereoisomers and racemic mixtures, their
pharmaceutically acceptable pro-drugs and salts.
[0027] In the general Formula (I): [0028] R.sub.1, R.sub.2,
R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.10,
are, independently of each other, either H, OH, .dbd.O, and OR
where R=optionally substituted alkyl, optionally substituted acyl,
optionally substituted carbamoyl, alkoxycarbonyl; [0029] R.sub.9,
R.sub.12, R.sub.11, R.sub.13 can be either a H, OH, OR where
R=optionally substituted alkyl, optionally substituted acyl,
optionally substituted carbamoyl, alkoxycarbonyl; [0030]
R.sub.14=optionally substituted alkyl group, [0031] .....
represents an optional double bond, but excluding where
simultaneously: [0032]
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, [0033] R.sub.3.dbd..beta.OH, [0034] R.sub.14.dbd.CH.sub.3
[0035] the methyl group at C22 is .alpha., [0036] the C20 is
.alpha., and there is a S configuration at C25.
[0037] Preferably, in the general formula (I): [0038] R.sub.4,
R.sub.9, R.sub.12, R.sub.13.dbd.H [0039] R.sub.1, R.sub.2, R.sub.3,
R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.10, can be independently
of each other either H, OH, .dbd.O, OR where R=optionally
substituted alkyl, optionally substituted acyl, optionally
substituted carbamoyl, alkoxycarbonyl; [0040] R.sub.11.dbd.H, OH,
OR where R=optionally substituted alkyl, optionally substituted
acyl, optionally substituted carbamoyl, alkoxycarbonyl; [0041]
R.sub.14=optionally substituted alkyl group [0042] and .....
represents an optional double bond, but excluding where
simultaneously: [0043]
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, [0044] R.sub.3.dbd..beta.OH, [0045] R.sub.14.dbd.CH.sub.3,
[0046] the methyl group at C22 is .alpha., [0047] the C20 is
.alpha., and there is a S configuration at C25.
[0048] More preferably, in the general formula (I): [0049]
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub.7.dbd.R-
.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.sub.13.dbd-
.H, [0050] R.sub.3.dbd.H, --OH, --OMe, --OCOCH.sub.3, .dbd.O,
--O--CO--OEt, --O--CO--(CH.sub.2).sub.2--CO.sub.2H [0051]
R.sub.14.dbd.CH.sub.3, [0052] but excluding where simultaneously
[0053]
R.sub.1.dbd.R.sub.2.dbd.R.sub.4.dbd.R.sub.5.dbd.R.sub.6.dbd.R.sub-
.7.dbd.R.sub.8.dbd.R.sub.10.dbd.R.sub.11.dbd.R.sub.9.dbd.R.sub.12.dbd.R.su-
b.13.dbd.H, [0054] R.sub.3.dbd..beta.OH, [0055]
R.sub.14.dbd.CH.sub.3, [0056] there is a S configuration at C25,
[0057] the C20 is .alpha. and the methyl group at C22 is
.alpha..
[0058] In the general formula (II): [0059] R.sub.1, R.sub.2,
R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.10,
are, independently of each other, either H, OH, .dbd.O, or OR where
R=optionally substituted alkyl, optionally substituted acyl,
optionally substituted carbamoyl, alkoxycarbonyl; [0060] R.sub.9,
R.sub.12, R.sub.11, R.sub.13 can be either a H, OH, OR where
R=optionally substituted alkyl, optionally substituted acyl,
optionally substituted carbamoyl, alkoxycarbonyl; [0061]
R.sub.14=optionally substituted alkyl group; [0062] R.sub.15=H,
optionally substituted alkyl, optionally substituted acyl, or
glucosyl; [0063] ..... represents an optional double bond.
[0064] Preferably, in the general formula (II): [0065] R.sub.4,
R.sub.9, R.sub.12, R.sub.13.dbd.H [0066] R.sub.1, R.sub.2, R.sub.3,
R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.10, can be independently
of each other either H, OH, .dbd.O, OR where R=optionally
substituted alkyl, optionally substituted acyl, optionally
substituted carbamoyl, alkoxycarbonyl; [0067] R.sub.11.dbd.H, OH,
OR where R=optionally substituted alkyl, optionally substituted
acyl, carbamoyl, alkoxycarbonyl; [0068] R.sub.14=optionally
substituted alkyl group [0069] R.sub.15=H, optionally substituted
alkyl, optionally substituted acyl, or glucosyl; [0070] and .....
represents an optional double bond.
[0071] The following compounds are particularly preferred:
##STR2##
[0072] As used hereabove and hereafter:
[0073] "Acyl" means an H--CO-- or Alkyl--CO-- group wherein the
alkyl group is as herein described. Preferred acyls contain a lower
alkyl. Exemplary acyl groups include formyl, acetyl, propanoyl,
2-methylpropanoyl, butanoyl and palmitoyl.
[0074] "Alkyl" means an aliphatic hydrocarbon group which may be
straight or branched having about 1 to about 20 carbon atoms in the
chain. Preferred alkyl groups have 1 to about 12 carbon atoms in
the chain. Branched means that one or more lower alkyl groups such
as methyl, ethyl or propyl are attached to a linear alkyl chain.
"Lower alkyl" means about 1 to about 4 carbon atoms in the chain
which may be straight or branched. Exemplary alkyl groups include
methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, n-pentyl,
3-pentyl.
[0075] "Optionally substituted" means that the said group may be
substituted with one or more substituents which may be the same or
different, and include halo, alkyl, cycloalkyl, hydroxy, alkoxy,
amino, acylamino, aryl, aroylamino, carboxy, alkoxycarbonyl,
aralkoxycarbonyl, heteroaralkoxycarbonyl, optionally substituted
carbamoyl.
[0076] The term "pharmaceutical composition" means a composition
comprising a compound of formula I or II and at least one component
selected from the group comprising pharmaceutically acceptable
carriers, diluents, adjuvants, excipients, or vehicles, such as
preserving agents, fillers, disintegrating agents, wetting agents,
emulsifying agents, suspending agents, sweetening agents, flavoring
agents, perfuming agents, antibacterial agents, antifungal agents,
lubricating agents and dispensing agents, depending on the nature
of the mode of administration and dosage forms.
[0077] "Pharmaceutically acceptable" means it is, within the scope
of sound medical judgement, suitable for use in contact with the
cells of humans and lower animals without undue toxicity,
irritation, allergic response and the like, and are commensurate
with a reasonable benefit/risk ratio.
[0078] "Pharmaceutically acceptable dosage forms" means dosage
forms of the compound of the invention, and includes, for example,
tablets, dragees, powders, elixirs, syrups, liquid preparations,
including suspensions, sprays, inhalants tablets, lozenges,
emulsions, solutions, granules, capsules and suppositories, as well
as liquid preparations for injections, including liposome
preparations. Techniques and formulations generally may be found in
Remington, Pharmaceutical Sciences, Mack Publishing Co., Easton,
Pa., latest edition.
[0079] "Pharmaceutically acceptable prodrugs" as used herein means
those prodrugs of the compounds useful according to the present
invention which are, within the scope of sound medical judgment,
suitable for use in contact with the tissues of humans and lower
animals with undue toxicity, irritation, allergic response, and the
like, commensurate with a reasonable benefit/risk ratio, and
effective for their intended use, as well as the zwitterionic
forms, where possible, of the compounds of the invention. The term
"prodrug" means compounds that are rapidly transformed in vivo to
yield the parent compound of the above formula, for example by
hydrolysis in blood. Functional groups which may be rapidly
transformed, by metabolic cleavage, in vivo form a class of groups
reactive with the carboxyl group of the compounds of this
invention. Because of the ease with which the metabolically
cleavable groups of the compounds useful according to this
invention are cleaved in vivo, the compounds bearing such groups
act as pro-drugs. A thorough discussion of prodrugs is provided in
the following: Design of Prodrugs, H. Bundgaard, ed., Elsevier,
1985; Methods in Enzymology, K. Widder et al, Ed., Academic Press,
42, p.309-396, 1985; A Textbook of Drug Design and Development,
Krogsgaard-Larsen and H. Bundgaard, ed., Chapter 5; Design and
Applications of Prodrugs p.113-191, 1991; Advanced Drug Delivery
Reviews, H. Bundgard, 8, p.1-38, 1992; Journal of Pharmaceutical
Sciences, 77, p. 285, 1988; Chem. Pharm. Bull., N. Nakeya et al,
32, p.692, 1984; Pro-drugs as Novel Delivery Systems, T. Higuchi
and V. Stella, Vol.14 of the A.C.S. Symposium Series, and
Bioreversible Carriers in Drug Design, Edward B. Roche, ed.,
American Pharmaceutical Association and Pergamon Press, 1987, which
are incorporated herein by reference.
[0080] "Pharmaceutically acceptable salts" means the relatively
non-toxic, inorganic and organic acid addition salts, and base
addition salts, of compounds of the present invention. These salts
can be prepared in situ during the final isolation and purification
of the compounds. In particular, acid addition salts can be
prepared by separately reacting the purified compound in its free
base form with a suitable organic or inorganic acid and isolating
the salt thus formed. See, for example S. M. Berge, et al.,
Pharmaceutical Salts, J. Pharm. Sci., 66: p.1-19 (1977) which is
incorporated herein by reference. Base addition salts can also be
prepared by separately reacting the purified compound in its acid
form with a suitable organic or inorganic base and isolating the
salt thus formed. Base addition salts include pharmaceutically
acceptable metal and amine salts.
[0081] Some sapogenin derivatives of interest in the present
invention may occur naturally in a range of plant species, notably
from the genera Smilax, Asparagus, Anemarrhena, Yucca and Agave.
The species presently of greatest interest include Smilax regelii
Kilip & Morton--commonly known as Honduran sarsaparilla; Smilax
aristolochiaefolia Miller--commonly known as Mexican sarsaparilla;
Smilax ornata Hooker--commonly known as Jamaican sarsaparilla;
Smilax aspera--commonly known as Spanish sarsaparilla; Smilax
glabra Roxburgh; Smilax febrifuga--Kunth--commonly known as
Ecuadorian or Peruvian sarsaparilla; Anemarrhena asphodeloides
Bunge; Yucca schidigera Roezl ex Ortgies; and Yucca brevifolia
Engelm. Sapogenin derivatives which may be of interest may also
occur naturally in other genera, for example Dioscorea, Trillium,
Solanum, Strophanthus, Digitalis and Trigonella. However, some
sapogenin derivatives from these sources possess undesirable
properties and are thus not recommended for use in the
invention.
[0082] Sapogenin derivatives of the invention may also be
commercially available; suppliers are well-known from the one
skilled in the art and may include Sigma Aldrich, Research Plus
Inc., Steraloids Inc., etc...
[0083] According to a further aspect of the invention, there is
provided a process of preparation of the compounds of the
invention.
[0084] Substitued sapogenins of the present invention may be
prepared by synthetic methods. For instance, they may be prepared
from unsubstituted sapogenin derivatives, which may occur naturally
or be commercially available, as stated above.
[0085] Starting from these unsubstituted sapogenins, the reaction
may involve at least one substitution step, wherein the functional
group is substituted on the sapogenin derivative; usually, the
starting product is an unsubstituted sapogenin having the required
sterechemistry, and the reaction may involve the substitution of
one OH-- group by the functional radical desired; smilagenin and
epismilagenin are preferred as starting products.
[0086] Compounds useful according to the invention may be prepared
by the application or adaptation of known methods, by which is
meant methods used heretofore or described in the literature, for
example those described by R. C. Larock in Comprehensive Organic
Transformations, VCH publishers, 1989.
[0087] In the reactions described hereinafter it may be necessary
to protect reactive functional groups, for example hydroxy or
carboxy groups, where these are desired in the final product, to
avoid their unwanted participation in the reactions. Conventional
protecting groups may be used in accordance with standard practice,
for examples see T. W. Green and P. G. M. Wuts in "Protective
Groups in Organic Chemistry" John Wiley and Sons, 1991; J. F. W.
McOmie in "Protective Groups in Organic Chemistry" Plenum Press,
1973.
[0088] The compound thus prepared may be recovered from the
reaction mixture by conventional means. For example, the compounds
may be recovered by distilling off the solvent from the reaction
mixture or, if necessary after distilling off the solvent from the
reaction mixture, pouring the residue into water followed by
extraction with a water-immiscible organic solvent and distilling
off the solvent from the extract. Additionally, the product can, if
desired, be further purified by various well techniques, such as
recrystallization, reprecipitation or the various chromatography
techniques, notably column chromatography or preparative thin layer
chromatography.
[0089] According to a further aspect of the present invention,
there is provided a pharmaceutical composition having cognitive
function enhancing properties which comprises an effective amount
of a sapogenin derivative of the invention.
[0090] In a still further aspect, the sapogenin derivatives of the
present invention are steroidal; they are preferably
non-oestrogenic in effect.
[0091] In another aspect, the invention provides a pharmaceutical
composition having cognitive function enhancing properties which
comprises an effective amount of a sapogenin derivative of the
invention in the form of an extract derived from a plant of the
genus Smilax, Asparagus, Anemarrhena, Yucca or Agave.
[0092] It will be appreciated that the invention embraces within
its scope the use of the compositions defined above. Thus,
according to a fifth aspect, the present invention provides a
method of enhancing cognitive function which comprises
administering to a human or animal an effective dosage of a
composition of the invention.
[0093] The invention also provides a method of enhancing cognitive
function in a human or non-human animal, which comprises
administering an effective dose of sapogenin derivatives of the
invention. Also, it concerns the use of the sapogenin derivatives
of the invention in food product or beverage for enhancing
cognitive function.
[0094] As used herein, the term "cognitive function" refers to
functions such as thinking, reasoning, remembering, imagining and
learning.
[0095] According to a further aspect, the invention also relates to
composition having cognitive function enhancing properties which
comprises at least two, preferably two, sapogenin derivatives of
the invention.
[0096] In identifying compounds that would have use in the
treatment of SDAT and other diseases characterised by reductions in
receptor numbers or synaptic transmission, the inventors have given
consideration to the need to identify compounds that would have the
desired effect but would be devoid of any oestrogenic effects, as
these would be unacceptable, particularly in male patients. A
number of the compounds claimed to have activity in patent
application DE 4303214A1 have marked oestrogenic activity and are
therefore unacceptable. Preferably, sapogenin derivatives of the
present invention however, does not display oestrogenic activity.
In addition these compound were tested at other steroid receptors
and were found to have no activity at any of the following
receptors:
Progesterone
Glucocorticoid
Testosterone
[0097] Sapogenin derivatives of the present invenion have also been
tested for activity in a number of in-vitro assays. The
assays/experiments that were considered of key importance in
determining possible activity in the elevation of membrane bound
receptor numbers were as follows: [0098] Chinese hamster ovary
(CHO) cells transfected with the a DNA fragment coding for a
muscarinic receptor. The cell line used for the majority of the
experiments was a cell line expressing the m2 receptor.
[0099] The methods and the results of these experiments are now
described in turn.
CHO cell line experiments
[0100] The effects of various compounds on the expression of m2
receptors on CHO cells transfected with DNA for the m2 receptor
were investigated. Receptor numbers were assayed using tritiated
QNB binding and subtracting non-specific binding. Compounds were
dissolved in DMSO and DMSO was used as a control. Compounds were
tested at a range of final concentrations. Compounds were also
tested in the presence and absence of tamoxifen to try to
distinguish an oestrogen receptor mediated mechanism.
[0101] Compounds are active when the effect on receptor expression
given as a percentage increase compared to control is more than
15%.
[0102] The results are summarised in the Table 1 below.
TABLE-US-00001 TABLE 1 Effects of sapogenin derivatives on the
expression of m, receptors on CHO cells Compound Molar
concentration Activity ##STR3## 10.sup.-5 Active ##STR4## 10.sup.-5
Active ##STR5## 10.sup.-5 Active ##STR6## 10.sup.-5 Active ##STR7##
10.sup.-5 Active ##STR8## 10.sup.-5 Active ##STR9## 10.sup.-5
Active ##STR10## 10.sup.-5 Active ##STR11## 10.sup.-5 Active
##STR12## 10.sup.-5 Active ##STR13## 10.sup.-5 Active ##STR14##
10.sup.-5 Active ##STR15## 10.sup.-5 Not active ##STR16## 10.sup.-5
Not active ##STR17## 10.sup.-5 Not active ##STR18##
10.sup.-510.sup.-6 Not active Not active ##STR19## 10.sup.-5 Not
active ##STR20## 10.sup.-510.sup.-6 Not active Not active ##STR21##
10.sup.-5 Not active ##STR22## 10.sup.-5 Not active ##STR23##
10.sup.-510.sup.-6 Not active Not active ##STR24## 10.sup.-5 Not
active ##STR25## 10.sup.-5 Not active ##STR26## 10.sup.-5 Not
active ##STR27## 10.sup.-510.sup.-6 Not active Not active ##STR28##
10.sup.-5 Not active ##STR29## 10.sup.-5 Not active ##STR30##
10.sup.-5 Not active ##STR31## 10.sup.-5 Not active
[0103] Thus the experiments indicate that the sapogenin derivatives
of the invention were able to increase the number of muscarinic
receptors expressed on the surface of CHO cells cultured in-vitro.
The effect was not antagonised by tamoxifen, indicating that the
mechanism involved did not involve the oestrogen receptor.
[0104] It appears from the experimental work conducted that the
compounds of this invention act to normalise muscarinic receptor
number--i.e. they tend to prevent decline in receptor number with
time, and also tend to restore receptor number to normal levels
when given to cells in which the receptor number is depressed.
[0105] It is speculated here that the effect of the active compound
claimed in this patent may operate through an effect on G protein
and that the effects on receptor numbers are secondary to an effect
on G-protein. When a membrane bound G-protein linked receptor is
stimulated two basic sets of events are initiated: the effecter
response; and the internalisation of the receptor. The subsequent
processing of the receptor to the state where it is again in a form
on the cell surface or other membrane surface where it can interact
with another receptor ligand appears to be subject to a number of
factors. A number of these factors or mechanisms appear to be
G-protein linked. There is evidence that activation of m.sub.3
receptors may have an effect on G-protein expression or levels. It
is speculated that the actions of the compounds described in this
patent may due to an interaction in the processes of receptor
regeneration, G-protein linkage or G-protein homeostasis.
[0106] An alternative hypothesis is that the compounds are
increasing the synthesis or release or a decreased rate of
degradation of neurotropic factors such as brain derived growth
factor and/or nerve growth factor. These effects on growth factors
might be due to an effect of the compound on a cytosolic or nuclear
receptor or the binding of a compound to a promoter region with a
consequent effect directly on the rate of production of mRNA for
the growth factor or as a consequence of increasing the production
of another material factor such as G-protein or finally the effects
may be secondary to an effect on receptor or G-protein
procession.
[0107] The increased expression and/or abnormal processing of the
amyloid precursor protein (APP) is associated with the formation of
amyloid plaques and cerebrovascular amyloid deposits which are the
major morphological hallmarks of Alzheimer's disease. Of particular
interest are the processes regulating the proteolytic cleavage of
APP into amyloidogenic and nonamyloidogenic fragments. The cleavage
of APP by the enzyme .alpha.-secretase within the .beta.-amyloid
sequence of the protein results in the formation of a non
amyloidogenic C-Terminal fragment, and the soluble APPs.alpha.
fragment; this latter fragment has been shown to have neurotropic
and neuroprotective activity as well as to enhance memory in mice
when injected intra-cerebro-ventrically (ICV). In contrast,
processing of APP by .beta.-secretase exposes the N-terminus of
.beta.-amyloid which is released by .gamma.-secretase cleavage at
the variable C-terminus. The resulting .beta.-amyloid peptides,
which contain 39-43 amino acids, have been shown to be neurotoxic
and to accumulate in plaques which interfere with inter-neurone
connections.
[0108] A number of studies have shown that stimulation of the
protein-kinase (PKC) linked muscarinic M.sub.1 and M.sub.3
receptors results in an increase in .alpha.-secretase activity. As
a consequence processing of APP to APPs.alpha. with its
neuroprotective effects is increased. In parallel, processing of
APP by .beta.- and .gamma.-secretase is decreased and there is a
consequential reduction of .beta.-amyloid. Other transmitters such
as nerve growth factor (NGF) and brain derived neurotropic factor
(BDNF) as well as bradykinin and vasopressin may have similar
effects in increasing the proportion of APP processed to
APPs.alpha.. There may be a number of factors involved in the
effects of NGF which may include binding of the factor to the
tyrosine kinase receptor (TrkA) and the stimulation of
phospholipase C.gamma. with subsequent phosphorylation and
activation of protein kinase C (PKC) and increase in relative
activity of .alpha.-secretase.
[0109] Any treatment which increases activity of protein-kinase C
selectively in brain might therefore be expected to be of use in
the management of Alzheimer's disease. Until recently agonists
selective at the M.sub.1 receptor have not been available.
Non-selective agonists would be expected to stimulate pre-synaptic
M.sub.2 receptors which cause negative feedback and hence would
further severely impair muscarinic transmission. Selective agonists
at the M.sub.1 receptor are now becoming available (talsaclidine)
and such agents are under investigation for the treatment of AD.
There is however, a substantial risk that, as with the chronic
administration of any receptor agonist, the clinical benefits seen
will be severely limited in terms of the size of benefit by
reducing receptor numbers or reducing sensitivity and in terms of
side effects due to lack of receptor specificity. Thus compounds as
described in this invention, which selectively regulate muscarinic
receptor number or function, would be expected to be devoid of the
problems seen with a muscarinic agonist and hence have particular
utility. Indeed the benefits may be seen in three parts as follows.
[0110] 1. A selective increase in M.sub.1 receptor numbers leading
to increased synaptic transmission. Chronic administration of a
selective agonist will, at best, have no adverse effect on
transmission; [0111] 2. Secondary to the increased receptor
numbers, an increase stimulation of PKC with a consequential
increase in .alpha.-secretase activity, leading to: [0112] 2.1 A
reduced production of .beta.-amyloid and a consequent reduction of
plaque formation and neuronal loss; [0113] 2.2 An increase in
APPs.alpha. and a consequent improvement in cerebral function as
witnessed by an improvement in short and long term memory.
[0114] In order to illustrate the invention further by way of
non-limiting example, reference will now be made to the
accompanying drawings and to the Example which follows; in the
drawings:
[0115] FIGS. 1, 2, 3 illustrate the results obtained in Example 1
below,
[0116] FIG. 4 illustrates a hypothetical mode of action for
sapogenin derivatives;
[0117] Referring to FIG. 4, a diagrammatic representation of the
function of sapogenin derivatives of the invention is shown. It is
believed that sapogenin derivatives act primarily on cell nuclei;
the invention is not, however, limited to any particular mode of
action. The observed increase in muscarinic receptor number
consequential upon administration of sapogenin derivatives is
interpreted as leading to increased expression of muscarinic
receptor protein. The possible link between the secretases and
.beta.-amyloid protein formation (discussed above) is indicated in
the drawing.
[0118] The following examples are provided to illustrate the
invention in a non-limiting manner.
EXAMPLE 1
[0119] In a CHO cell line expressing recombinant human muscarinic
receptors in vitro, the number of muscarinic receptors tends to
decline with time. Sapogenin derivatives of the invention (1-10
.mu.M) incubated for 72 hours increase muscarinic receptor
density.
Methods:
[0120] Effect of sapogenin derivatives of the invention on
muscarinic receptor density in CHO cells expressing recombinant
human muscarinic receptors.
[0121] Chinese hamster ovary (CHO) cells expressing high levels of
receptor (.about.2.2 pmoles receptor/mg protein) were cultured in
flasks (150 ml) for 24 hours before the start of the experiment.
Vehicle (DMSO) and sapogenin derivatives (at 1 and 10 .mu.M) were
added to the medium for 48 h. The culture medium was discarded, the
cells scraped off and resuspended in Hanks solution, centrifuged
and m-receptor levels determined by incubating with [.sup.3H]-QNB
for 30 min followed by liquid scintillation counting. Protein
levels were determined by a micro Lowry method.
Results:
[0122] These are illustrated in FIGS. 1-3. Over the culturing
period treatment with sapogenin derivatives of the invention
prevents the decrease in muscarinic receptor number in a
concentration-dependent manner.
EXAMPLE 2
3-O-Ethoxycarbonyl-5.beta., 20.alpha., 22.alpha.,
25R-spirostan-3.beta.-ol
[0123] ##STR32##
[0124] Ethyl chloroformate (1.40 g, 12.9 mmol) was added dropwise
to a stirred solution of smilagenin (2.08 g, 5.0 mmol) in anhydrous
dichloromethane (15 ml) and anhydrous pyridine (1.02 g, 12.9 mmol).
The mixture was stirred at room temperature for 18 h and then
partitioned between water (30 ml) and dichloromethane. The aqueous
layer was extracted twice with dichloromethane, the combined
organic layers washed with water and then dried over MgSO.sub.4
(anhyd). The solvent was evaporated in vacuo to give an oil (2.1 g)
that rapidly crystallised. This material was chromatographed on
silica (ca. 70 g). Elution with ethyl acetate-hexane (1:9) and
recrystallisation from methanol afforded white crystals
of3-O-ethoxycarbonyl-5.beta., 20.alpha., 22.alpha.,
25R-spirostan-3.beta.-ol (1.08 g):mp 154-156.degree. C.; m/z 488
(M.sup.+ for C.sub.30H.sub.48O.sub.5); .sup.1H nmr (270 MHz,
CDCl.sub.3) .delta.0.76 (3H, s, 18-CH.sub.3), 0.78 (3H,
s,27-CH.sub.3),0.95 (3H, s,21-CH.sub.3), 0.98 (3H, s,
19-CH.sub.3),1.0-2.05 (27H, complex m, aliphatics), 1.31 (3H, t,
J=7 Hz, CO.sub.2--C--CH.sub.3), 3.33-3.46 (2H, m,
26-OCH.sub.2),4.18 (2H, q, J=7 Hz, CO.sub.2CH.sub.2),4.40 (1H, m,
16--OCH), 4.95 (1H, m, H-3) ppm; .sup.13C nmr (270 MHz, CDCl.sub.3)
14.3 (C--C--O.sub.2C), 14.5, 16.5, 17.1, 20.9, 23.7, 25.0, 26.4,
28.8, 30.3, 30.6, 31.4, 31.8, 35.0, 35.3, 37.0, 40.0, 40.3, 40.7,
41.6, 56.4 (C-14), 62.3 (C-17), 63.6 (C--O.sub.2C), 66.9 (C-26),
74.8 (C-3), 80.9 (C-16), 109.2 (C-22), 154.8 (carbonyl) ppm;
R.sub.f 0.65 (silica, ethyl acetate-hexane, 1:9)
EXAMPLE 3
Epismilagenin Succinate
[0125] ##STR33##
[0126] A solution of epismilagenin (200 mg, 0.48 mmol) and succinic
anhydride (60 mg, 0.59 mmol) in anhydrous pyridine was stirred at
room temperature under nitrogen overnight. A further portion of
succinic anhydride (120 mg, 1.18 mmol) was added and the reaction
stirred for a further 24 h. After addition of a further portion of
succinic anhydride (120 mg, 1.18 mmol) the reaction was heated at
50.degree. C. with stirring for a further 24 h. After the reaction
was cooled, water (10 ml) was added and the aqueous solution
extracted with diethyl ether (4.times.20 ml). The combined organic
extracts were washed with water (3.times.20 ml), dried (MgSO.sub.4
anhyd) and filtered. The solvent was evaporated in vacuo to give an
orange oil (1.8 g) that was chromatographed on silica gel using
ethyl acetate/petroleum ether (1:4) as eluent. Recrystallisation of
the product from acetone afforded white crystals of epismilagenin
succinate (87 mg); mp 180-182.degree. C.; .sup.1H nmr spectrum
(CDCl.sub.3, 270 MHz): partial data .delta.4.75 (1H, m), 4.6 (1H,
m), 3.50 (1H, dd), 3.40 (1H, t), 2.6 (4H, br dd), 0.98 (3H, d) 0.95
(3H, s), 0.80 (3H, d), 0.75 (3H, s) ppm; .sup.13C nmr spectrum
(CDCl.sub.3, 68 MHz): .delta.171.81, 109.27, 80.91, 74.90, 66.85,
62.25, 56.29, 41.84, 41.62, 40.65, 40.51, 40.18, 35.44, 35.01,
34.72, 32.17, 31.77, 31.38, 30.25, 29.33, 28.79, 26.93, 26.55,
23.58, 20.58, 17.11, 16.43, 14.48 ppm; R.sub.f 0.11 (silica, ethyl
acetate-petroleum ether, 3:7)
* * * * *