CS219415B1 - Method of pure ergocornine preparation - Google Patents

Abstract

A method for preparing pure ergocornine from a crude mixture of ergot alkaloids, consisting in converting the crude mixture of levorotatory and dextrorotatory enantiomers by boiling in a mixture of alcohols C1 to C4 with ethyl to butyl acetate or a lower aliphatic ketone Cx to C4, with at least one molar equivalent of phosphoric acid, into hydrophosphate of levorotatory alkaloids, from which the alkaloid base is released, after purification on a silica gel column and crystallization from methanol, followed by crystallization from a mixture of methanol with ethyl or butyl acetate 1:10, methanol with dioxane 1:1 to 5:1, acetone and benzene.

Description

The subject of the invention is a method for isolating ergocornin from a mixture of alkaloids, represented by other alkaloids of the ergotoxin group, accompanied by a limited amount of ergotamine alkaloids in the form of both left and right-handed enantiomers and another group of peptide alkaloids. . N- [N- (d-lysergyl) -L-valyl] -L-phenylalanyl-D-proline lactam, N- [N- (d-lysergyl) -L-valyl] -L-leucyl-D-proline lactam, and N- [N- (d-lysergyl) -L-valyl] -L-valyl-D-proline lactam}.

In the latter group, the isolation of the first member, its destructive products and prepared derivatives in the literature has been described by JStutz et al., Experientia 29, 936 (1973); Cerny et al. Collectio-n 41, 3415 (1976)], and the other two put forward the assumption of a blind strand formation of the theoretically assumed scheme for the blosynthesis of peptide ergot alkaloids [Floss et al. Experiments 30, 1369 (1974)]. The ergocornin isolation process described below economically and reliably separates the other alkaloids of all groups, said lactam alkaloids and the destructive products formed therefrom during the operations.

The starting alkaloid mixture may be a crude sum of alkaloids isolated by ergot extraction, mycelium obtained by fermentation, or waste bases remaining after separation of the major portion of the ergaloin group alkaloids.

Ergocornin was obtained by Stoll et al. [Helv. Chim. Acta 26, 1570 (1943); Briton. U.S. Pat. 573 514] of pure levorotatory ergotoxin of different composition and commercial origin; the mixture of ergotoxin alkaloids was separated by a procedure using different solubilities of the salts of the individual members of the ergotoxin group (ergocrisin, ergocornin, ergocryptin) with di-p-toluyl-D-tartaric acid. The fractional crystallization of the mixture carried out in this manner is both resource intensive (preparation of substituted non-natural tartaric acid necessary) and laborious (the salt of said acid with ergocornin is most soluble) and appears more suitable for analytical purposes than industrial preparation of ergocornin. The same authors used the ergotoxin group's ability to crystallize from methanol to separate ergocornin from a mixture of alkaloids.

We were convinced that even with ergotoxin predominantly ergocornin, crystallization from methanol can yield a highly enriched material by ergocornin, which can be further deprived of concomitant alkaloids by repeatedly but lossy crystallization and obtain a highly enriched concentrate with ergocornin but usually reaches the stage where ergocornin crystallizes isomorphically with some ergocryptine and further crystallization is no longer effective.

Ergocornin was further prepared by partial synthesis by Stadion et al. Helv. Chem. Acta 52, 1563 (1969). To separate ergocornin and ergocorninin isolated from the reaction mixture, the authors used silica gel column chromatography and ethyl acetate-acetone 20: 1. The more preferred synthesis uses mixed trifluoroacetic anhydride as an intermediate. The preparation of ergocornin in admixture with ergosine via submersible fermentation is described in Swiss patent 518 361 by the company. Farmitalia, 1972. After extraction of the alkaloids from the mycelium and partial shaking, the alkaloid mixture is precipitated from the solution with hexane and chromatographed in chloroform on a silica gel column. The appropriate fractions were crystallized from benzene and recrystallized from methanol or ethanol

According to the work of Beran and Semonský [Cs. Pharmacy 11, 440 (1962)] directed principally to the separation of ergotoxin group alkaloids from ergotamine group alkaloids in a chloroform-aqueous tartaric acid system, it is possible to separate from ergotoxin a portion of ergocornin which passes into the acidic aqueous phase. . Such a material can also be used to isolate ergocornin.

Ergocornin, because of its ability to crystallize from methanol or ethanol, differs from the other alkaloids of the ergotoxin family in that it is not possible to prepare its dextrorotatory enantiomer by boiling in alcohols such that it is continuously excreted in crystalline form while boiling from solution. Ergocorninin has to be prepared by establishing an equilibrium between ergocornin and ergocornin, for example by treatment with alkali under defined conditions, and the ergocorninin can be isolated from the mixture as a crystal from ethyl acetate-ether.

Thus, it is also laborious to obtain ergocornin from ergocorninin if the reverse sequence of enantiomer processing is utilized. Ergocorninin is mentioned because it is present in the raw alkaloid mixtures to be processed and the efficiency of the process described below is also in that it converts ergocorninin to the desired ergocornin, thereby greatly improving the economy of the process.

It can be seen from the above overview that either relatively pure mixtures of left-handed alkaloids of the ergotoxin group or mixtures of ergocornine-ergosine have been used for the preparation of ergocornin, but not as in our case raw materials containing both left and right-handed alkaloids of various groups. with a non-cyclol structure or their degradation products. According to the elaborated process, a crystalline mixture of alkaloid phosphate is precipitated from solution and the dextrorotatory alkaloids are simultaneously converted into levorotatory; In the mother liquor there remains only a small amount of the mixture of right and left-handed alkaloids.

Ergotoxin hydrophosphate was first prepared by Barger and Carr J. Chem. Soc. 91, 337 (1907) from crude ergotoxin. This procedure, however, followed the preparation of ergotoxin, then considered a chemically uniform substance. Improved procedure according to MS. No. 86,237 is based on a mixture of amorphous alkaloid tartrate, which is converted into a mixture of base phosphates by aqueous ethanolic phosphoric acid. The preparation of ergocornine hydrophosphate by recrystallization of a 90% aqueous ¹ alcohol residue is described in the basic Stoll paper by Helv. Chem. Acta. 36, 1570 (1943). The above processes are not suitable for the economical production of ergocornin, either they are only suitable for preparing the pure salt of the individual, or do not provide sufficient yield when applied to the described material, or further processability (filtration, artifacts) is impeded.

According to the invention, a crude alkaloid mixture containing up to 40% of non-alkaloid ballasts and in addition to the ergotoxin component up to 10% of the ergotamine alkaloids and up to 15% of the lactam structure alkaloids in both left and right-handed forms can be processed into pure ergocornin. to reflux in a mixture of alcohol _(ϋ χ to C / J with ethyl through butyl ester of acetic acid or a lower aliphatic ketone (C _s to. ₅ C), preferably in a mixture of ethanol and ethyl acetate or acetone in a ratio of · 1:

: 1 to 1: 4 sec. one mol equivalent of phosphoric acid.

¹ from the isolated alkaloids hydrogen phosphate alkali liberated base is taken up in an organic solvent immiscible with water, preferably in ether, methylene chloride and chloroform accident- after passage through alumina residue obtained is subjected to purification by column chromatography on silica gel in a suitable solvent mixture, preferably in chloroform at mixtures with ether or acetone. The base obtained from the eluate is crystallized first from methanol, a lever from a mixture of methanol with ethyl or butyl acetate (1: 10) and, after conversion of the crystal to an amorphous chloroform residue from a mixture of methanol with dioxane or tetrahydrofuran (1: 1 to 5: 1). ).

Preferably methanol may be used in admixture with dioxane. The almost pure ergocornine base thus obtained is still crystallized from acetone and finally from benzene. We have found that the order of solvents used for crystallization is interchangeable. Crystallization from the solvent mixture exhibited a higher purification capability than from methanol alone. The ergocornin bases thus prepared can be used to prepare addition salts with common organic and inorganic acids or to hydrogenate the double bond dvoj ^9.10 resulting in dihydroergocornin, or to modify the structure resulting in partially synthetic variations in the ergocornin molecule.

Ergocornin and its derivatives exhibit significant pharmacodynamic effects. In the form of the methanesulfone salt of its Δ ⁹¹⁰ dihydroderivative, it is, together with other hydrogenated alkaloids of the ergotoxin group, part of sympatholytic formulations. The mechanism of mildly hypotensive effect and increasing oxygen availability in brain tissue was also investigated. Ergocornin exhibits antinidative, antifertility, inhibits pituitary prolactin secretion. It suppresses progesterone secretion and induces esirus. The anti-tumor activity of ergocornin was tested and ergocornin was also tested as an anti-parkinsonicum. The emetic effect of ergocornin has so far been considered as one of the manifestations of side effects.

The process of the invention is described in more detail in the following examples, and the examples do not limit the scope of the invention.

He did

Solution 6,5 g of crude alkaloid mixture (total; alkaloid content 86,0%, ergocornin:

(ergocryptine 3: 2, ergotamine 5%) in 10 ml of ethanol-ol-ethyl acetate 1: 1 was heated to reflux and a solution of one mol equivalent of phosphoric acid in ethyl acetate was added dropwise as soon as reflux was reached. Ethyl acetate (15 ml) was added in small portions and the reaction mixture with crystallized hydrophosphate was added for a further 20 min. keeps under ref lux. After cooling the reaction mixture, 6 g of crystalline hydrophosphate are isolated from which the base is liberated by stirring with 1.2 g of sodium bicarbonate in 50 ml of dilute aqueous ammonia solution. The liberated base is transferred by repeated extraction into 800 ml of diethyl ether. After-. drying the ether solution and drying; The base was taken up in chloroform and evaporated to dryness (4.8 g).

The residue obtained is dissolved in chloroform a ^; The residue is chromatographed on a column of Merck silica gel (15 g) in chloroform-acetone 9: 1. 2.6 g of a crystal with a ratio of ergocornine: ergocryptine of about 3: 1 are obtained. Subsequent crystallization from ethyl acetate-methanol 10: 1 and after conversion of the crystal to a chloroform residue by crystallization from dioxane-methanol 1: 1 reduce the ergocryptine content to 1.00. 5 to 1% and approx

1.5 g crystal.

After re-conversion to an amorphous residue and crystallization from 5 ml of acetone, the obtained crystal has a maximum of 1% of the accompanying alkaloids and a whitish color. For analytical evaluation, a crystal obtained from acetone was recrystallized from 3 times benzene and after filtration and drying, 1.1 g of benzene base ergocornine was obtained. The bases falling off in the individual stages can be used to obtain an additional proportion of ergocornin and ergocryptine, or to isolate materials for partially synthetic derivatives.

The total alkaloid content in the dried substance (titr. In anhydrous medium) 99.1% «) n ²⁰ (c - 1, chloroform) —179.9 and ergocornin content 99.3 ^! % ergocryptine content 0.7% other alkaloids not shown by thin layer chromatography.

Example 2 g of waste bases from ergotoxin production (total alkaloid content 65%; ergotoxic component - ergocornin 65%, ergocryptine 25% / o, ergocristin 10% / o, ergotamine 8% / o, lactam alkaloids 10%) 30 ml of ethanol-acetone 2: 1 and heated to boiling. Upon reflux and the slow addition of dissolved phosphoric acid mol equivalents in ethyl acetate, crystalline hydrophosphate starts to precipitate. After crystallization of the salt, 30 ml of acetone are added dropwise to the reaction mixture and the mixture is maintained for a further 20 minutes. under reflux. 9.0 g of ergotoxinium hydrophosphate are isolated from the cooled mixture and the base is subsequently liberated by stirring with 1.8 g of sodium bicarbonate in 75 ml of dilute ammonia. The free base was repeatedly extracted into ether (1200 ml) and distilled off under reduced pressure to a chloroform residue. After dissolution in a minimal amount of 2: 1 chloroform-ether, the chloroform base of ergotoxin was subjected to chromatography on a 25 g / m silica gel column in the same mixture as the base was dissolved. The uniform fractions were concentrated to a residue (6.8 g) and crystallized from 15 ml of methanol. The obtained 3 g crystal was dissolved in 6 ml of butyl acetate while hot, and after addition of 1.2 ml of methanol, relatively pure ergocornin (1.8 g) crystallized. The crystal upon conversion to the chloroform residue was crystallized from 1: 1 methanol-dioxane (1.3 g of crystal). After re-conversion to an amorphous chloroform residue, it crystallizes first from 7 ml of acetone and then from three times benzene. Benzene crystallized ergocornin (1.0 g) exhibited the following physical constants after drying:

Total alkaloid content in dried substance (titre, anhydrous) 99.0% («) d ²⁰ (c = 1, chloroform) —180.3 ergocornine content 98.8% ergocryptine content 0.5% ergocristine content 0.7 % other alkaloids not shown by thin layer chromatography.

The waste bases from the individual production stages can be used for the isolation of ergocryptine, ergocristine, other ergocornine fractions and for the preparation of materials for partially synthetic derivatives.

Claims (1)

Process for preparing pure ergocornin from a crude ergot alkaloid mixture, characterized in that the crude mixture of levorotatory and dextrorotatory enantiomers is converted by boiling in an environment of a mixture of alcohol C ₁ to C ₄ with ethyl to butyl ester of acetic acid or lower aliphatic ketone C ₁ to C ₄ with one mole equivalent of phosphoric acid in dextrorotatory levaloalkane alkaloids, which liberate the alkaloid base, purify on a silica gel column and crystallize from methanol followed by crystallization from a 1: 10 mixture of methanol with ethyl or butyl ester, methanol with dioxane 1: 1 to 5 : 1, acetone and benzene.