U.S. patent application number 09/178962 was filed with the patent office on 2002-04-04 for method of preparing delta-9-tetrahydrocannabinol.
This patent application is currently assigned to Elsohly Et Al. Invention is credited to ELSOHLY, MAHMOUD A., ROSS, SAMIR A..
Application Number | 20020039795 09/178962 |
Document ID | / |
Family ID | 22654636 |
Filed Date | 2002-04-04 |
United States Patent
Application |
20020039795 |
Kind Code |
A1 |
ELSOHLY, MAHMOUD A. ; et
al. |
April 4, 2002 |
METHOD OF PREPARING DELTA-9-TETRAHYDROCANNABINOL
Abstract
A method of preparing tetrahydrocannabinol using extraction of
plant material with a non-polar solvent followed by vacuum
distillation and collection of a constant boiling fraction.
Additional distillation steps and chromatographic steps, including
HPLC reversed phase HPLC and flash chromatography, may be
performed.
Inventors: |
ELSOHLY, MAHMOUD A.;
(OXFORD, MS) ; ROSS, SAMIR A.; (OXFORD,
MS) |
Correspondence
Address: |
EUGENE C. RZUCIDLO
GRAMAM & JAMES LLP
885 THIRD AVENUE
22ND FLOOR
NEW YORK
NY
10022
|
Assignee: |
Elsohly Et Al
|
Family ID: |
22654636 |
Appl. No.: |
09/178962 |
Filed: |
October 26, 1998 |
Current U.S.
Class: |
436/177 ;
210/634; 210/656; 436/161; 436/93; 514/454; 549/385; 549/388 |
Current CPC
Class: |
G01N 30/02 20130101;
B01D 15/325 20130101; Y10T 436/142222 20150115; Y10S 436/901
20130101; Y10T 436/255 20150115; G01N 2001/4027 20130101; G01N
2030/126 20130101; G01N 2030/009 20130101; G01N 30/12 20130101;
G01N 2001/4033 20130101; Y10T 436/25375 20150115; G01N 30/02
20130101 |
Class at
Publication: |
436/177 ; 436/93;
436/161; 210/634; 210/656; 514/454; 549/385; 549/388 |
International
Class: |
G01N 001/18; C07D
311/78; C07D 311/94 |
Claims
1. A method for the isolation of delta-9-tetrahydrocannabinol (THC)
from Cannabis plant material comprising: a) extracting the Cannabis
plant material with a non-polar organic solvent to form an extract;
b) removing the solvent from the extract to give a residue; and c)
subjecting the residue to low pressure flash distillation and
collecting a first distillate containing THC from a constant
boiling range in the distillation.
2. The method of claim 1, further comprising subjecting the first
distillate of the flash distillation to an additional low pressure
flash distillation to further purify the first distillate and to
form a second distillate.
3. The method of claim 2, further comprising subjecting the second
distillate to column chromatography using solvents or solvent
mixtures having progressively increasing polarities and collecting
an eluate containing THC.
4. The method of claim 1, further comprising subjecting the residue
to column chromatography by elution with solvents or solvent
mixtures with progressively increasing polarities and collecting
fractions containing THC therefrom prior to flash distillation.
5. The method of claim 4, further comprising subjecting the first
distillate to column chromatography by elution with solvents or
solvent mixtures with progressively increasing polarities and
collecting fractions containing THC therefrom.
6. The method of claim 2, further comprising subjecting the first
distillate to column chromatography by elution with solvents or
solvent mixtures with progressively increasing polarities and
collecting fractions containing THC therefrom.
7. The method of claim 1, further comprising subjecting the first
distillate from the flash distillation to flash column
chromatography using solvents and/or solvent mixtures with
progressively increasing polarities and collecting fractions
containing THC therefrom.
8. The method of claim 1, further comprising subjecting the first
distillate from the flash distillation to normal phase HPLC using
solvents or solvent mixtures with progressively increasing
polarities and collecting fractions containing THC therefrom.
9. The method of claim 1, further comprising subjecting the first
distillate from the flash distillation to reverse phase HPLC using
solvents or solvent mixtures with progressively decreasing
polarities and collecting fractions containing THC therefrom.
10. The method of claim 4, further comprising subjecting the first
distillate from the flash distillation to normal phase HPLC using
solvents or solvent mixtures with progressively increasing
polarities and collecting fractions containing THC therefrom.
11. The method of claim 4, further comprising subjecting the first
distillate of the flash distillation to reversed phase HPLC using
solvents or solvent mixtures with progressively decreasing
polarities and collecting fractions containing THC therefrom.
12. The purified THC obtained from the process of any one of claims
l, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11.
Description
BACKGROUND OF THE INVENTION
[0001] Delta-9-tetrahydrocannabinol (THC, also known as dronabinol)
is the main biologically active component in the Cannabis plant
which has been approved by the Food and Drug Administration (FDA)
for the control of nausea and vomiting associated with chemotherapy
and, more recently, for appetite stimulation of AIDS patients
suffering from the wasting syndrome. The drug, however, shows other
biological activities which lend themselves to possible therapeutic
applications, such as in the treatment of glaucoma (1), migraine
headaches (2, 3), spasticity (4), anxiety (5), and as an analgesic
(4). It is because of these-promising biological activities of THC
that marijuana has been brought into a public debate relative its
medicinal value. The balance between medicinal use of a drug and
the abuse potential is a delicate balance. One of the main points
brought by the medicinal marijuana proponents is the fact that the
currently available soft gelatin capsule formulation is very
expensive and lacks consistency in its effects. The latter point
could be explained based on the fact that oral THC has erratic
absorption from the gastrointestinal tract, is subject to the
first-pass effect resulting in heavy metabolism with production of
high levels of 11-OH-THC, and undesirable side effects. Another THC
formulation which is currently under development is a pro-drug
consisting of THC hemisuccinate formulated in a suppository base
(6). This formulation appears to overcome the problems associated
with the oral preparation and has been shown to produce consistent
bioavailability in animal studies (7). Preliminary clinical
investigations show promise for this formulation (8, 9, 10). It is
anticipated that other THC formulations will be forthcoming in
light of the current interest in the therapeutic activities of
cannabis.
[0002] Regardless of which formulation is to be used for THC or a
pro-drug thereof, a source for the raw material is critical. The
currently-approved capsule formulation is prepared from synthetic
THC which is extremely expensive to produce. It is thought that
should an economic process be developed for isolation of THC from
the natural material (cannabis), then the cost of the raw material
could be brought down significantly, making it possible to develop
such formulations at a reasonable cost to the public. The
consequence of this would be the availability of alternative
therapies involving THC (or a prodrug thereof) which would help in
suppressing the public outcry for approval of marijuana as a
medicine.
[0003] Several investigations have been carried out over the years
to isolate THC from the plant material, mostly to determine its
chemical structure or to investigate the phytochemistry of the
plant. In 1942, Wollner, et al., (11) reported the isolation of
tetrahydrocannabinol from cannabis extract "red oil". Red oil was
prepared by extraction of the plant material with ether, followed
by distillation of the concentrated extract at room pressure
followed by redistillation under reduced pressure (15-50 mm Hg).
The oil was acetylated with acetic anhydride, and the acetylated
product was subjected to fractional distillation in vacuo. Six
fractions were collected. The head and tail fractions were removed.
The remaining four fractions which represented the principal
fractions (fractions 2, 3, 4, and 5) were combined and passed over
silica gel column in benzene and then passed over activated alumina
in carbon tetrachloride solution. The product was hydrolyzed by
acid, alkali, or ammonia in alcoholic solution. The authors
reported that the deacetylated product has, in each case, a
different physiological potency than the acetate. All fractions
were not pure compounds.
[0004] DeRopp, in 1960 (12), described the isolation of THC from
the flowering tops of Cannabis sativa. His method involved
adsorption chromatography of the methanolic extract of cannabis
followed by partition chromatography on Celite using N,N-dimethyl
formamide/cychlohexane mixture and high vacuum distillation. The
purity of THC was based on paper chromatographic evidence.
[0005] The first isolation of the naturally occurring THC in its
pure form was reported by Gaoni and Mechoulam in 1964 (13). THC was
isolated from the hexane extract of hashish by repeated column
chromatography on florisil and alumina. Further purification was
carried out by the preparation of the crystalline
3,5-dinitrophenylurethane of THC followed by mild basic hydrolysis
to get the pure THC. The purity of THC was proven by thin layer
chromatography (TLC) and spectroscopic analysis (IR and NMR).
[0006] Korte, et al., in 1965 (14) reported the isolation of THC
from the crude extracts of the female inflorescence of Cannabis
sativa indica and Cannabis sativa non indica. The crude extracts
were chromatographed over activated alumina in order to remove the
coloring impurities like carotinoids, chlorophylls, and
xanthophylls. All the cannabinolic fractions were combined and
concentrated to give a brownish-red oil. The oil was further
purified by a countercurrent distribution method to get THC which
was proved to be identical with that described by Gaoni and
Mechoulam (13).
[0007] In 1967, Mechoulam and Gaoni (15) reported the isolation of
THC from the acidic fraction of the hexane extract of hashish. The
hexane extract of hashish was separated into acidic and neutral
fractions. The acidic fraction was chromatographed on florisil or
acid washed alumina. The column was eluted with pentane-ether
mixtures in a manner of increasing polarities. THC was eluted with
15% ether in pentane. Repeated chromatography was carried out by
the preparation of crystalline derivative
(3,5-dinitrophenylurethane THC, m.p., 115-116.degree. C.) followed
by hydrolysis.
[0008] In 1972, Verwey and Witte (16) reported a method for the
preparation of THC by isolation of THC acid from hashish. The
hexane extract was shaken with 2% NaOH solution as well as 2%
sodium sulphite in an extraction funnel. The alkaline layer was
rendered acidic with H.sub.2SO.sub.4(pH<2), thus precipitating
the cannabinoid acids. The oily layer as well as the oily deposits
on the wall were extracted with ether. The acid-base extraction
process was repeated. THC was obtained from the impure acids by
heating the ether solution containing the acids on a sand bath with
a temperature of 300.degree. C. The ether being evaporated, the
evaporating dish was for a moment kept on the sand bath, in this
way causing decarboxylation of THC acid. The THC was cleaned by
preparative TLC.
[0009] In summary, for isolation of THC and other cannabinoid
constituents, generally the alcoholic or the petroleum ether or
benzene or hexane extract of the plant is separated into neutral
and acidic fractions. These fractions are further purified by
repeated column chromatography and countercurrent distribution or a
combination of these methods. Various adsorbents have been used in
column chromatography, especially silica gel, silicic acid, silicic
acid-silver nitrate, florisil, acid washed alumina, and acid washed
alumina-silver nitrate. Most of the above-discussed methods were
used for the preparation of a small amount of THC and not for
large-scale production.
[0010] If THC is to be prepared in large-scale (kilogram)
quantities, an efficient and economic method is needed. Such a
method would require an efficient isolation procedure.
SUMMARY OF THE INVENTION
[0011] The present invention is for the preparation of THC from
Cannabis plant material. Simple, high yielding steps are developed
which reduce the cost of preparation of THC several fold over the
synthetic route
[0012] The present invention comprises a process wherein Cannabis
plant material is extracted with a non-polar organic solvent to
provide an extract containing THC and the extract is subjected to
fractional distillation under reduced pressure to provide a
distillation fraction (distillate) having a high content of THC.
The instant process further comprises subjecting the extract from
the plant material to column chromatography prior to fractional
distillation. A still further aspect of the instant process
comprises subjecting the distillate from the fractional
distillation to column chromatography. Additionally, the present
invention includes the use of high pressure liquid chromatography
(HPLC) in the purification of the extract from the plant
material.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The present invention relates to a process for providing an
efficient and economic method for isolating THC from Cannabis plant
material. The plant material is extracted with a non-polar organic
solvent. Useful solvents include lower alkanes, such as, for
example, hexane, heptane or iso-octane. The extract containing THC,
after solvent removal, is subjected to fractional distillation
under reduced pressure and a first distillate is collected. In one
embodiment of the present invention, the first distillate is again
subjected to fractional distillation at reduced pressure and a
second distillate is collected. The second distillate has a THC
content of greater than 90% by wt.
[0014] In another embodiment of the invention the crude extract
from the plant material is first subjected to column
chromatography. One possible method by which the material can be
placed on the column is by mixing the extract residue in an organic
solvent with a portion of the column packing material and
transferring the dried slurry onto the top of a packed column.
Direct application of the extract residue in the initial elution
solvent (minimum volume) directly to the top of the packed column
is also possible. The column is eluted with an organic solvent in a
manner such that the column is eluted with a solvent or a solvent
mixture with progressively increasing polarity. The fraction or
fractions containing the major portion of THC from the column
elution is subjected to fractional distillation at reduced
pressure. Distillate is collected in the substantially constant
boiling temperature range and this distillate was found to contain
greater than 90% by weight THC. THC with purity of greater than
95%, preferably greater than 98% can be obtained by further
purification of the distillate from the fractional distillation by
column chromatography or by normal or reversed phase HPLC.
[0015] The column chromatography can be carried out using any known
packing material including, for example, silica or alumina for
normal phase operation or C.sub.18 or C.sub.8 bonded phase silica
for reversed phase operation. Elution of the normal phase
chromatography column is carried out with solvents having an
increasing polarity. Non-polar solvents include the lower straight
chain and branched chain alkanes, including, for example, pentane,
hexane, isooctane and petroleum ether. More polar solvents include
various organic ethers, alcohols, esters or ketones, including, for
example dialkyl ethers, lower alkyl acetates, lower dialkyl ketones
and lower alkanols. Illustrative polar solvents include, for
example, acetone, ethylacetate, diethylether and isopropyl alcohol.
The ratio of non-polar solvent to polar solvent can vary between
100:0 to 80:20.
[0016] Elution chromatography under the reversed phase conditions
is carried out with solvents having decreasing polarities. These
solvents include water or acidic buffer as the polar portion and
lower alkanol (such as methanol, ethanol and isopropanol) or
acetonitrile as the less polar portion, in mixtures ranging from
50:50 to 0:100 aqueous to organic. The chromatographic process can
also be carried out under HPLC conditions in much the same way as
described above under either normal or reversed phase operation
using a preparative scale column.
[0017] Flash distillation is carried out under reduced pressure,
i.e. under vacuum at pressures below 1 mm Hg, preferably close to
0.1 mm Hg.
[0018] It will be understood by those skilled in the art that
various modifications and substitutions may be made to the
invention as described above without departing from the spirit and
scope of the invention. Accordingly, it is understood that the
present invention has been described by way of illustration and not
limitation.
EXAMPLE 1
[0019] Extraction
[0020] 200 g of the air-dried and powdered buds (7.82% THC) and 270
g of the air-dried and powdered buds (6.61% THC) were mixed and
extracted by maceration at room temperature with hexane for 24
hours (2.2 L Hexane.times.4). The hexane extracts were combined and
evaporated under vacuo to give 76.5 g (16.3% extractives).
[0021] Column Chromatography
[0022] 56 g of the hexane extract (40% THC) was mixed with 100 g
silica gel (silica gel 60, E. Merck) and 50 ml hexane. The dried
slurry was transferred onto the top of a silica gel column (850 g
silica gel 60, dimensions: 10.times.60 cm). Elution was carried out
with petroleum ether and ether in a manner of increasing
polarities. Twelve fractions were collected and TLC screened.
Identical fractions were pooled together. The fraction eluted with
Pet.ether-ether (9:1) was evaporated to give 37.3g of residue which
showed THC content of 55.87% using gas chromatography (GC)
analysis. This fraction contained the majority of THC (93%) in the
material applied onto the column.
[0023] Fractional Distillation
[0024] A portion (7.1 g) of the collected fraction was subjected to
fractional distillation under vacuum (between 0.08-0.1 mmHg) to get
two major fractions, one collected between 170-175.degree. C. (2.34
g @ 90% THC) and one between 175-180.degree. C. (1.32 g @ 88.2%
THC).
EXAMPLE 2
[0025] Extraction
[0026] The air-dried and powdered buds (380g, 2.20% THC) were
extracted with hexane by maceration at room temperature for 24
hours (1.8 L hexane X 3 ). The total weight of the hexane extracts
was 29.1 g (7.7% extractives). The % of THC in the hexane extract
was 28.76%.
[0027] Column Chromatography
[0028] The hexane extract (29.1 g) was mixed with 100 g of silica
gel (silica gel 60, E. Merck) and 50 ml hexane. The dried slurry
was transferred on to the top of silica gel column (850 g silica
gel 60, Dimensions: 10.times.60 cm). Elution was carried out with
petroleum ether-ether mixtures in a manner of increasing
polarities. Nine fractions were collected and TLC screened.
Identical fractions were pooled together to give 4 fractions. The
fraction collected with petroleum ether-ether (9:1) was evaporated
to yield 13.3g of residue. GC analysis of this fraction showed a
concentration of THC of 58.98%, again representing >93% recovery
of all THC in the material applied to the column.
[0029] Fractional Distillation
[0030] A portion (7.3 g) of the fraction collected above was
subjected to fractional distillation at vacuum (0.08-0.1. mmHg).
The major fraction (3.738 g) was collected between 172-180.degree.
C. and was found to contain 89% THC by weight.
EXAMPLE 3
[0031] One kg of the fine powdered marijuana plant material
[average % of THC was about 5.21%] was macerated with 6L hexanes
(Hexanes GR from EM Sciences) in a percolator (9" in diameter from
the top and 20" long, cone shaped) for 24 hours at room temperature
and filtered. The macerate was reextracted with 5L hexanes for
another 24 hours. The hexane extracts were combined and evaporated
under reduced pressure at low temperature to give 110.7 g residue
(11.07% extractives). The % of THC in the hexane extract was
41.21%.
[0032] Column Chromatography
[0033] The hexane extract (110.7 g) was mixed with 150 g silica gel
(silica gel 60, Art.# 9385-3) and 50 ml hexane. The air dried
slurry was transferred to the top of a silica gel column (800 g
silica gel 60, particle size 0.04-0.063 mm, from EM Science, Art. #
9385-3). The column was eluted with hexane: ether mixtures in a
manner of increasing polarities. Fractions were collected and TLC
screened (analytical silica gel plates, developing system: Hexane:
Ether (80:20), Visualizing agent: Fast blue). The fractions
collected with hexane (3 L.) and hexane-ether (95:5, 2 L.) were
discarded. The following fractions collected with hexane-ether
(95:5, 3 L.) and hexane-ether (9:1, 5 L.) were combined and
evaporated to yield 77.2 g of residue. GC analysis of the residue
showed THC concentration to be 54.74%.
[0034] Fractional Distillation
[0035] A portion (30.5 g) of the residue collected above was
subjected to fractional distillation under reduced pressure
(0.1-0.15 mm/Hg). The temperature was slowly raised to 125.degree.
C. and the materials collected were kept separate. The temperature
was then raised between 140-160.degree. C. where the major fraction
was collected (14 g). GC analysis showed>96% THC.
EXAMPLE 4
[0036] One kg of the fine powdered marijuana plant material
[average % of THC is 4.42] was macerated with 6 L hexanes and
extracted by the same procedure followed in Example 3 to yield
105.8 g residue (10.58% extractives). The % of THC in the hexane
extract was 40.35% by GC analysis.
DIRECT FRACTIONAL DISTILLATION OF THE HEXANE EXTRACT
[0037] A portion (23.0 g) of the hexane extract was subjected to
fractional distillation under reduced pressure (vacuum, 0.1-0.2
mm/Hg). The temperature was raised slowly to 160.degree. C. where a
small amount of material (<1 g) was collected and left separate.
The major fraction (10.1 g) was collected between 170 and
180.degree. C. GC analysis of this fraction showed 72.66% THC
concentration.
[0038] A second portion (25.0 g) of the hexane extract was
subjected to fractional distillation under similar conditions as
the first portion. The major fraction collected between
170-180.degree. C. weighed 11.6 g and had a THC concentration of
73.62%.
[0039] A third portion (25.0 g) of the hexane extract was subjected
to fractional distillation under similar conditions to the previous
portions. The major fraction containing THC weighed 10.2 g and had
a THC concentration of 73.72%.
[0040] The three major fractions obtained from the above three
distillations were combined and analyzed. The analysis showed the
concentration of THC to be 70.31%. The mixture (28.9 g) was
subjected to fractional distillation, again under similar
conditions. The temperature was raised slowly to 135.degree. C.
under vacuum (0.1-0.15 mmHg) and the fractions collected were kept
aside. The major THC containing fraction was collected at
140-160.degree. C. and 0.05-0.06 mm/Hg. The fraction weight was
18.4 g and the THC content was 92.15%.
EXAMPLE 5
[0041] A portion (0.8 g) of the pure THC obtained in Example No. 3
(% of THC was about 96%) was mixed with one gram silica gel (silica
gel 60) and one ml hexane. The dried slurry was transferred on to
the top of a silica gel column (12 silica gel 60, Dimensions:
1.times.50 cm). Elution was carried out with hexane:ether mixtures
in a manner of increasing polarities. Six fractions were collected
and screened using TLC. Fraction Nos. 3-5 (hexane:ether 98:2) were
combined and yielded 0.63 g of residue (% of THC was 98%).
EXAMPLE 6
[0042] One gram of the THC prepared in Example No. 4 (purity was
about 92%) was mixed with one gram of silica gel (silica gel 60)
and one ml hexane. The dried slurry was transferred on to the top
of a silica gel column (13 g silica gel 60, dimensions: 1.times.50
cm). Elution was carried out under similar conditions as under
Example 5. Fraction nos. 3-5 yielded 0.78 g of residue (% of THC
was 98%).
EXAMPLE 7
[0043] 1000 g of the air-dried and powdered Cannabis buds %of THC
by GLC analysis was 6.49%) were extracted by maceration at room
temperature for 24 hours (5L.times.3, Lot. No. 970424). The hexane
extracts were combined and evaporated under vacuo to give 97 g
residue.
[0044] 67 g of the hexane extract was dissolved in 200 ml isooctane
(Lot. No. 904038) and the solution was transferred onto the top of
a silica gel column (280 g silica gel, 40 .mu.m particle size,
dimensions of column: 10.times.60 cm). The column was eluted with
iso-octane:methyl-t-butyl ether mixture 8:2 (3L, fraction 1) and
then washed with methanol (1 L, fraction 2). GLC analysis of
fraction 1 (53 g) showed a concentration of THC of 55.56%.
FRACTIONAL DISTILLATION
[0045] Fraction 1 (53g) was subjected to fractional distillation at
vacuum 0.1-0.6 mm/Hg. The major fraction (20.0 g) was collected
between 160-170.degree. C. and was found to contain 94% THC by
weight.
PURIFICATION OF THC BY HPLC
[0046] 10 g of the major fraction (purity about 94%) was purified
on HPLC (water Delta prep 4000) connected to a Waters 486 Tunable
absorbance detector and using column Prep PAK500/silica. The eluent
was iso-octane:methyl-t-butyl ether mixture (98:2). The flow rate
was programmed to be 10 ml/minute for 10 minutes, 25 ml/minute for
60 minutes and finally 50 ml/minute for 200 minutes.
[0047] The results are summarized in the following table:
1 TIME VOLUME ANALYSIS FRACTIONS (minutes) (ML) WEIGHT (G) FOR THC
1 22-43 600 trace 2 67-72 300 0.3 g 3 72-74 100 0.9 g 4 74-81 450
2.7 g 96.6% 5 81-97 800 4.0 g 99.0% 6 97-100 1200 1.9 g 97.5%
PURIFICATION OF THC PREPARED BY FRACTIONAL DISTILLATION USING FLASH
COLUMN CHROMATOGRAPHY
EXAMPLE 8
[0048] 2.1 g of THC (91% purity) were dissolved in 10 ml isooctane
and the solution was transferred onto the top of a silica gel
column (30 g silica gel, 40 .mu.m particle size; dimensions of the
column: 2.5 cm.times.40 cm ). The column was eluted with isooctane
then a mixture of isooctane-acetone (99:1). Seven fractions were
collected and analyzed by GLC. Isooctane-acetone (99:1) fractions
containing the bulk of the THC were contained and yielded 1.84 g of
residue (% of THC was 97%).
EXAMPLE 9
[0049] 1 g of THC (91% purity) was dissolved in 5 ml isooctane and
the solution was transferred onto the top of a silica gel column
(15 g silica gel, 40 .mu.m particle size, dimensions: 2.5
cm.times.40 cm). The column was eluted with isooctane- ethyl
acetate mixture in a manner of increasing polarities and the
fractions were collated. Fraction No. 5 (eluted with
isooctane-ethylacetate 98:2) yielded 0.56 g of residue (% of THC
was 97%). Fraction No. 4 (eluted with iso-octane-ethylacetate
98.5:1.5) yield 0.32 g of residue (% of THC was 94.9%).
EXAMPLE 10
[0050] 1.1 g of THC (91% purity) was dissolved in 5 ml isooctane
and the solution was transferred onto the top of a silica gel
column (15 g silica gel, 40 .mu.m particle size, dimensions: 2.5
cm.times.40 cm ). The column was eluted with a mixture of
isooctane: isopropyl alcohol in a manner of increasing polarities.
Five fractions were collected. Fraction Nos. 4 and 5 (eluted with
iso-octane-isopropyl alcohol (98:2 and 95:5, respectively) were
combined and yielded lg of residue (% of THC was 94%).
PURIFICATION of THC BY HPLC (REVERSED PHASE)
EXAMPLE 11
[0051] 9.6 g of THC (purity 92.8%) was purified on HPLC (Water
Delta Prep 4000) connected to Waters 486 Tunable absorbance
detector (wave length used: 254 nm) and using Column Prep Pak C18
(from Waters, Dimensions 46 mm.times.30 cm, 55-105 ,.mu.m, Lot no.
T 72852). The eluent was a mixture of methanol: water ( 75:25). The
flow rate was programmed to be 10 ml/minute for 10 minutes, 25
ml/minute for 50 minutes and finally 50 ml/minute for 140 minutes.
The results are summarized in the following table:
2 Time Volume Weight Analysis for Fraction (minutes) (ml) (g) THC 1
69-96 1400 0.10 2 96-105 500 0.34 3 105-123 1000 6.00 99% 4 123-135
600 1.98 98% 5 135-155 1000 1.00 95% 6 174-180 300 0.10
SUMMARY
[0052] 1. THC can be prepared directly from a hexane extract of
Cannabis sativa L. by double fractional distillation. The purity of
THC by GLC analysis is about 90-92%. Further purification on a
silica gel column gives THC with approximately 98% purity.
[0053] 2. THC can be prepared directly from a hexane extract of
Cannabis sativa L. by column chromatography (silica gel) followed
by fractional distillation. The purity of THC is about 95-96%.
Further purification on a silica gel column gives THC with at least
98% purity.
REFERENCES
[0054] 1. ElSohly, M. A.; Harland, E.; and Waller, C. W.;
Cannabinoids in glaucoma II: The effect of different cannabinoids
on the intraocular pressure of the rabbit; Curr. Eye Res.;
3(6):841-850, 1984.
[0055] 2. El-Mallakh, R. S.; Marihuana and migraine, Headache,
27(3):442-443, 1987.
[0056] 3. Volfe, Z.; Dvilansky, I. A., and Nathan, I.; Cannabinoids
block release of serotonin from platelets induced by plasma from
migraine patients; Int. J. Clin Pharmacol. Res., 5(4):243-246,
1985.
[0057] 4. Maurer, M; Henn, V.; Dirtrich, A.; and Hofmann, A.;
Delta-9-tetrahydrocannabinol shows antispastic and analgesic
effects in a single case double-blind trial; Eur. Arch. Psychiatry
Clin. Neurosci., 240(1):1-4, 1990.
[0058] 5. McLendon, D. M., Harris, R. T.; Maule, W. F.; Suppression
of the cardiac conditioned response by
delta-9-tetrahydrocannabinol: A comparison with other drugs;
Psychopharmacology, 50(2): 159-163, 1976.
[0059] 6. ElSohly, M. A., Stanford, D. F.; Harland, E. C.; Hikal,
A. H.; Walker, L. A.; Little, T. L., Jr.; Rider, J. N.; and Jones,
A. B.; Rectal bioavailability of delta-9-tetrahydrocannabinol from
the hemisuccinate ester in monkeys; J. Pharm. Sci., 80(10):942-945,
1991.
[0060] 7. ElSohly, M. A., Little, T. L., Jr.; Hikal, A.; Harland,
E.; Stanford, D. F.; and Walker L. A.; Rectal bioavailability of
delta-9-tetrahydrocannabinol from various esters; Pharmacol.,
Biochem., Behav., 40:497-502, 1991.
[0061] 8. Mattes, R. D.; Shaw, L. M.; Edling-Owens, J., Engleman,
K.; and ElSohly, M. A.; Bypassing the first-pass effect for the
therapeutic use of cannabinoids; Pharm., Biochem., Behav.,
44(3):745-747, 1991.
[0062] 9. Mattes, R. D.; Engelman, K.; Shaw, L. M.; and ElSohly, M.
A.; Bypassing the first-pass effect for the therapeutic use of
cannabinoids, Pharmacol., Biochem., Behav., 49(1):187-195,
1994.
[0063] 10. Brenneisen, R.; Egli, A.; ElSohly, M. A.; Henn, V.; and
Speiss, Y.; The effect of orally and rectally administered
delta-9-tetrahydrocannabinol on spasticity: A pilot study with 2
patients; Inter. J. Clin. Pharmacol. and Therapeutics, 34(10)
:446-452, 1996.
[0064] 11. Wollner, H. J.; Matchett, J. R.; Levine, J.; and Loewe,
S.; Isolation of a physiologically active tetrahydrocannabinol from
Cannabis sativa resin; J. Am. Chem. Soc., 64:26-29, 1942.
[0065] 12. DeRopp, R. S.; Chromatographic separation of the
phenolic compounds of Cannabis sativa; J. Am. Pharmacol. Assoc.,
Sci. Ed., 49:756, 1960.
[0066] 13. Gaoni, Y.; and Mechoulam, R.; Isolation, structure, and
partial synthesis of an active constituent of hashish; J. Am. Chem.
Soc., 86:1646-1647, 1964
[0067] 14. Korte, F.; Sieper, H.; and Tira, S.; New results on
hashish-specific constituents; Bull. Narcotics, 17:35-43, 1965.
[0068] 15. Mechoulam, R.; and Gaoni, Y.; Recent advances in
chemistry of hashish; Fortschr. Chem. Org. NatStoffe, 25:175-213,
1967.
[0069] 16. Verwey, A. M. A.; and Witte, A. H.; A rapid method of
preparation of THC by isolation of THCA from hashish; Pharm.
Weekblad, 107:415-416, 1972.
* * * * *