CS259757B1 - A method for the drying of bile acids - Google Patents

Abstract

The purpose of the invention is the preparation of bile acids, especially ochenodeoxybolic acid, of high purity. The said purpose is achieved by intensive distillation of bile acid esters, crystallization of alkaline derivatives, their alkaline hydrolysis and precipitation with mineral acids, preferably HgSO4 and HCl.

Description

The invention relates to a process for the purification of crude bile acids, in particular chenodeoxycholic acid, by converting them into complexly acetylated esters.

Methods for purifying bile acids are known, for example by hydrolyzing a mixture of bile acid esters (KOH, NaOH) and cleaving the amino acid cortfugates of these acids when present in this form by »acidification (HCl, HgSO4) and extraction with a suitable solvent (ethyl acetate, ethyl ether, isopropyl ether, diisopropyl ether) is isolated by a mixture of free bile acids. Of these, individual acids are best obtained by converting these free acids into metal salts II. groups (Ca, Ba, Sr) which can be well distinguished and separated on the basis of different solubilities in suitable solvents. Acidification then yields the desired acid in pure form. The crude chenodeoxycholic acid can also be purified in a number of other ways - by conversion to the sodium or potassium salt, continuous extraction of ethyl acetate or isobutyl alcoholtoluene (45:55) and acidification or crystallization from acetonitrile containing 0-10% water and added to the crude acid in 8: 1 to 40: 1, recrystallization from dichloromethane, dichloroethane, esterification, purification of the ester on alumina with alcohol-chloroform solvent ester hydrolysis, acylation of the hydroxyl group with an organic acid at the 3-position or 7 followed by recrystallization, hydrolysis and neutralization, recrystallization from aqueous mixture lower alkyl acetate and alkane, or most recently by high pressure liquid chromatography on a hydrophilic stationary phase. The Japanese patent describes the distribution of ursodeoxyalcohol and chenodesoxycholic acid on a column packed with poly (styrene-divinylbenzene) by methanol purging (containing 5% water). The European patent uses silylation methods to separate these two acids, and the silylated acids are then easily separated by crystallization. The disadvantage of these methods is their lengthyness and technological demands. A further disadvantage is that incompletely acetylated chenodeoxycholic acid does not guarantee sufficient purification by simple recrystallization.

The above-mentioned disadvantages are overcome by the process according to the invention, which consists in the fact that bile crude acid is used. is converted into the methyl ester, respectively. other ester, and is intensively acetylated by conventional acetylation or acetylation. acylating agents, preferably a mixture of acetic anhydride and pyridine on a boiling water bath or with a ketone or acetyl chloride and the like. A completely acetylated ester is obtained which excellently crystallizes from methanol or ethanol. Thus, the bile acids in the form of these derivatives can be freed from the accompanying impurities.

Example:

100 g of chenodeoxycholic acid methyl ester are mixed with 100 ml of acetic anhydride and 50 ml of pyridine and heated at reflux in a water bath for 8 hours. Then cooled and left at room temperature for 24 hours. The acetylation solution is then diluted and shaken repeatedly with 1 N HCl of 50 ml and after addition of 100 ml of chloroform until the top layer remains acidic. The chloroform layer is then shaken vigorously with dry sodium sulfate and calcium carbonate until the rinsing reacts acidically. The chloroform solution is then evaporated to a syrup-like consistency and dissolved in 200 ml to 300 ml of methanol. After cooling, crystallization occurs. The white crystals are isolated on a aspirator and washed with a small amount of cooled methanol. This recrystallization is repeated 2 to 3 times, the yield being (depending on the raw material content) eg 53 g.

g of the acetylated ester is then heated with 200 to 300 ml of methanolic KOH at reflux for 3 hours (methanolic KOH: 12 g of KOH are dissolved in 10 ml of HgO and 90 ml of methanol are added). After the hydrolysis is complete, most of the methanol is distilled off, the residue is diluted with water, acidified, washed with distilled water and the white free-flowing precipitate is collected on a vacuum pump. Recrystallize in the usual manner. After recrystallization, it is converted to a melting point of more than 160 ° C.

The purity of the isolated chenodeoxycholic acid was checked by means of melting point, TLC, GLC, enzymatic conditions, by using 3-hydroxy steroid dehydrogenase, NMR, mass spectrometry, IR spectra, elemental analysis. Purity is greater than 95%.

Claims (1)

OBJECT OF THE INVENTION Process for the purification of crude bile acids, in particular chenodeoxycholic acid, characterized in that the bile acid esters are intensively acetylated, the derivatives obtained are crystallized and the free acids are prepared therefrom by alkaline hydrolysis and precipitation with a mineral acid, preferably H 2 SO 4 or RC 1. Uzhgorod Manufacturing and Policing Company Patent, Gagarina 101 W2326, Price 2,40 Kcs Uzgorod