FIELD OF THE INVENTION
The present invention pertains to the field of chemistry. More specifically it pertains to a process for biochemical synthesis of bioactive agroclavine an ergot alkaloid from lysergol via lysergene.
BACKGROUND OF THE INVENTION
Ergot refers to a group of fungi of the genus Claviceps. Ergot alkaloid is one of the pharmacologically most important groups of indole alkaloids isolated from the dried sclerotium of the fungus Claviceps purpurea. There are three main groups of ergot alkaloids as follows
• Clavine alkaloid type
• Water soluble lysergic acid type
• Water insoluble lysergic acid type / peptide ergot alkaloids
The clavine type of alkaloids such as agroclavine and elymoclavine are generally regarded as precursors to the other group of ergot alkaloids in the biogenetic pathways. Many of the ergot alkaloids are prolactin release inhibitors.
Agroclavine: It belongs to clavine type of alkaloid of ergot alkaloid group.
(Formula Removed)
Agroclavine
Structural formula of Agroclavine
IUPAC Name: (-) (5R) (10R) 8,9-Didehydro-6,8-dimethylergoline
Molecular formula : C16H18N2
Molar mass: 238.3275 g/mol Density: 1.161 g/cm3 Vapour pressure: 2.4E-07 mmHg at 25°C Flash point: 209.3 °C Index of refraction: 1.653 Boiling point: 422.5 degree celsius at 760 mm Hg
Characteristics: It is reported as toxic by intraporineal route , mutation data is also reported. When heated to decomposition, it emits toxic fumes of NO.
Properties: It decomposes at 198 - 203 degree celcius, easily soluble in alcohol, chloroform, pyridine, benzene, ether and slightly soluble in water.
Pharmacological uses of agroclavine
• It is a powerful uterine stimulant.
• Alkylated derivatives of agroclavine are potentially useful as antineoplastic drugs.
• It is cytostatically active
• It has weak antimicrobial activity against Staphylococcus aureus and Escherichia coli.
• Agroclavin helps in the process of implantation in uterus in case of mice.
• Intravenous injection of the ergot alkaloid agroclavine antagonizes depression induced by noradrenaline in the cerebral cortex of the rat.
• It has some inhibitory activity against cell proliferation in the L5178y mouse lymphoma system.
METHODS FOR SYNTHESIS OF AGROCLAVINE AS DISCLOSED IN PRIOR ART
The paper titled "Wittig methylenation of 9,10-didehydro-6-methylergoIin-8-0ne, a novel synthesis of lysergene and its subsequent conversion to agroclavine" written by William J. Wheeler,Lilly Research Laboratories, Eli Lilly and Co., Indianapolis, IN 46285, USA discloses the method of synthesis of agroclavine from lysergene where N-p-Ts-Iysergene was synthesized by the reaction of N-p-Ts-9, 10 -didehydro-6-methylergolin-8-one with methylene triphenylphosphorane. After that the synthesized N-p-Ts-lysergene was subjected to lithium/ammonia reduction and finally agroclavine is yielded.
From the above it is clear that the agroclavine which is synthesized from N-p-Ts-lysergene is (+) agroclavine whereas the agroclavine synthesized with the method of the present invention is a naturally occurring (-) agroclavine.
The article titled " Photocyclization of Enamides. XXXIII. Total Synthesis of Agroclavine, Fumigaclavine and Lysergene, Ichiya NINOMIYA' by Toshiko Kiguchi, Chiyomi Hashimoto and Takeaki NAITO of Kobe Women's College of Pharmacy, Motoyamakita, Higashinada, Kobe 658, Japan in Alkaloids Chemistry and Pharmacology discloses a method in which
(-)Agroclavine is synthesized from photocyclized lactam. It involves several steps as follows: The photocyclized lactam is subjected to subsequent oxidative cleavage of the dihydrofuran ring with ozone and reduction with lithium aluminium hydride. The 1,3-diols obtained from the above reaction are separated and mesylated with mesyl chloride to give corresponding dimesylates. The dimesylates are further treated with strong base, potassium tertiary butoxide in DMSO, unsaturated amine are yielded by double elimination. Lithium aluminium hydride reduction of the above unsaturated amine brought about deprotection of the nitrogen of the indoline skeleton. Finnally oxidative dehydrogenation of the indoline with phenylseleninic anhydride yields lysergene. When indoline is subjected to Birch reduction , a 2:1 mixture of C/D - trans and C/D - cis 1,4 - adducts is obtained. The trans adduct is treated with benzenelseleninic acid anhydride and is converted to (+)agroclavine.
Here the agroclavine which is synthesized from photocyclized lactam is a racemic mixture of agroclavine. In contrast in the present invention the agroclavine which is synthesized is optically active as well as biologically active.
US PATENT 2073954 describes the synthesis of a physiologically active ergot alkaloid. The process for synthesis of the ergot alkaloid comprises following steps:
Extracting ergot with petroleum ether.
Mixing the residue therefrom with magnesium hydroxide
Extracting said mixture with an inert solvent of the class consisting of benzene, chloroform,
dioxane and dichloroethylene.
Treating the solution of alkaloid so obtained in said inert solvent with acidulated water to form an
aqueous solution of a salt of the alkaloid
Treating said aqueous solution with a base to free the alkaloid from its salt
Extracting the alkaloid from the aqueous solution with an inert solvent of the said class
Evaporating inert solvent from the extract until crystals are produced
Separating the crystals and recrystallizing from a solvent of said class
Finally the ergot alkaloid is obtained. Here a positively rotatory physiologically active ergot alkaloid is synthesized from an alkalized ergot. In contrast, in the present invention a biologically active ergot alkaloid i.e. agroclavine is synthesized from lysergol with a different method and the product is negatively rotatory.
From the above it is clear that none of the prior art discloses a novel process for conversion of (+) lysergol via lysegene to (-) agroclavine of the type disclosed in the present invention.
OBJECT OF THE INVENTION
1. To disclose a novel process for conversion of (+) lysergol via lysegene to the ergot alkaloid (-)
agroclavine.
2. A novel process for synthesis of optically active agroclavine from lysergol via lysergene.
SUMMARY OF THE INVENTION
The present invention relates to a novel process for synthesis of bioactive agroclavine from lysergol via lysergene which is easy, less time taking and efficient in obtaining
(-)agroclavine of high yield and purity. The process of present invention is of commercial importance also as it allows large scale production of agroclavine.
BRIEF DESCRIPTION OF THE DRAWINGS
NIL - No drawings attached.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a novel process for synthesis of bioactive agroclavine from lysergol which obviates the drawback of existing processes which do not yield biologically active agroclavine. The agroclavine which is synthesized earlier is racemic mixture but the agroclavine which is synthesized in the present invention is bioactive as well as optically active.
NOVELTY ASPECT OF THE INVENTION
The present invention discloses a novel process for synthesis of bioactive agroclavine by conversion of (+) lysergol into (-) agroclavin. The product thus obtained in the present invention does not contain any synthetic or chemical additive . Such process has not been disclosed anywhere in the prior art to the best of inventor's knowledge nor can be easily visualized by a person skilled in the art.
INVENTIVE STEP
The inventive step of the process lies in simplification of synthesis of optically active agroclavine which is more useful in comparison to racemic agroclavine which are already available before. In the present invention agroclavine is synthesized in two steps i.e. from lysergol to lysergene in the presence of n-butanol and sodium metal, and finally lysergene to agroclavine in the presence of lithium and liquid ammonia.
INDUSTRIAL APPLICATION
The present method is simple, fast, cost effective and efficient in obtaining high yield and purity of bioactive agroclavine. The chemicals and reagents required for the synthesis of agroclavine are easily available commercially. In view of the easy availability of all the chemicals and reagents and simplicity of the process, the present invention allows commercial scale production of optically pure and bioactive agroclavine. The present invention enlarges the scope and use of agroclavine in therapeutic applications because of high purity of product.
DETAILED DESCRIPTION OF THE INVENTION :
The present invention describes the process for synthesis of a clavine type of ergot alkaloid i.e. agroclavine from lysergol via lysergene. The agroclavine which is reported in the prior art is of a racemic mixture, but in the present invention, the agroclavin which is synthesized is optically active and is also biologically active. The process for preparing bioactive agroclavine from lysergol via lysergene is described below:
1. Conversion of Lysergol to Lysergene : This comprises several steps which are briefly described as follows
(Formula Removed)
- A solution of lysergol <5g, 0.0196mol) in n-butanol (250 mL) containing sodium metal (3.47g, 0.1518 mol) is heated under reflux for 13 hours in an oil bath.
The reaction mixture is diluted with water <360mL) and extracted with benzene (2x200mL). The organic layer is extracted with tartaric acid (1%, 3xl60mL).
The acid solution is made alkaline (at pH=8) with IN NaOH solution and extracted with chloroform (3xl0mL).
The chloroform solution is dried over anhydrous sodium sulphate and evaporated to give brownish residue which on re-crystallization from ethyl acetate gives white material (1.32 g, 28.32%) which is charred at 235°C, m.p. 240°-245°C. Finally the white material obtained is Lysergene.
1. Conversion of Lysergene to Agroclavine : This involves several steps like follows
(Formula Removed)
Lithium (0.102 g, 0.030 mol) is added to dry and distilled liquid ammonia (200mL) and kept in a
three necked RB flask fitted with septums and a dropping funnel with pressure equaliser.
The flask is adjusted on plastic tray having saw dust.
The whole assembly is thus placed on a magnetic stirrer in properly ventilated hood.
The reaction mass is stirred for 30 min. A solution of lysergene (1.5g, 6.32x 10"3 mol) is dissolved
in dry 1,4 dioxane (100 mL) and reaction mass is stirred for five minutes. Absolute amount of
ethanol (8mL) is added to the solution drop wise.
The reaction mass is brought to room temperature to evaporate off liquid ammonia.
A solution of ammonium chloride (5g in 20mL H20) is added to give light brown to pink colored
solid (1.102g).
Finally it is collected by filtration. The purification by silica gel flash chromatography (28.8 cm,
3cm, 68 g) gives pure agroclavine (0.306 g, 42.85%) which is charred at 162°C, melts at 182°-
185°C.
The novel process of conversion of lysergol to agroclavine as dislosed above yields the product which can be experimentally analysed as follows.
1. U. V.spectral analysis of Agroclavine in ethanol (95%)
i) At 291 nm (maximum absorption)8
e=6520.29, log e=3.81 at 291 nm Reported b log ε =3.81 at 293 nm ii) At 281 nm (maximum absorption)a ε=7721.63, log e=3.88 at 281 nm Reported" log ε=3.88 at 284 nm iii) At 225 nm (maximum absorption)a
Reported11 log ε =4.47 at 225 nm
2. Estimation of Specific Optical Rotation of Agroclavine
-154.44° (c,0.9, chloroform)
Reported b= -155° (c=0.9, chloroform)
3. X Ray Analysis
The relative and absolute configuration of (-)agroclavine was confirmed by single crystal X-ray diffraction studies.
In the present invention the agroclavine which is obtained is optically active, the optical rotation being -154.44.
In the above detailed description of the invention, method of synthesis of bioactive agroclavine from lysergol has been disclosed. It is to be understood that this invention is not limited to any particular embodiments described as such and these may of course vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

WE CLAIM
1. A novel process for synthesis of bioactive (-)agrodavine from {+)lysergol wherein " the same
comprises of following steps :
Conversion of lysergol to lysergene in the presence of n-butanol and sodium metal;
Conversion of lysergene to{-) agroclavine in the presence of lithium and liquid ammonia.
2. The process as claimed in claim 1 wherein the conversion of (+)lysergol to lysergene comprises of
following steps:
A 2% solution of lysergol in n-butanol containing 1.4 % sodium metal is heated under reflux for 13 hours in an oil bath;
The reaction mixture is diluted with water and extracted with benzene ;
The organic layer is then extracted with tartaric acid;
The acid solution is made alkaline and extracted with chloroform ;
The chloroform solution is then dried over anhydrous sodium sulphate and evaporated to give brownish residue which on re-crystallization from ethyl acetate gives lysergene
3. The process as claimed in claim 1 and claim 2 wherein the conversion of lysergene to agroclavine
comprises of following steps:
0.05% Lithium is added to dry and distilled liquid ammonia and the reaction mass is stirred for 30 min. The solution of 1.5 % lysergene is dissolved in dry 1,4 dioxane and reaction mass is again stirred followed by addition of absolute ethanol;
The reaction mass is then brought to room temperature to evaporate the liquid ammonia;
A solution of 25 % ammonium chloride is added to precipitate the product agroclavine which is further purified by chromatography.
4. A novel process for synthesis of bioactive (-)agroclavine from (+)lysergol as described substantially
herein with reference to the detailed description.