Bile promoting drugs can generally be divided into two types: bile promoting agents and liquid enhancing bile promoting agents. The former refers to drugs that can promote bile secretion, while the latter refers to drugs that only increase bile volume but do not increase bile components. The commonly used cholestatic drugs are mainly bile acids. There are sodium cholic acid, dehydrocholic acid, chenodeoxycholic acid, and ursodeoxycholic acid.
Ursodeoxycholic acid is a chemical preparation that separates natural bile acids from bear bile. It is a stereoisomer of chenodeoxycholic acid, and its litholytic effect and therapeutic effect are similar to those of chenodeoxycholic acid, but the treatment course is short and the dosage is small. It combines with taurine in the body and exists in bile as a hydrophilic bile acid, serving as a cholesterol stone solubilizer. It can reduce the secretion of cholesterol by the liver, lower the saturation of cholesterol in bile, promote the secretion of bile acids, increase the solubility of cholesterol in bile, dissolve cholesterol stones, or prevent the formation of stones. It can increase the secretion of bile, relax the sphincter of the bile duct, and have a diuretic effect, which is conducive to the discharge of stones. This product cannot dissolve other types of gallstones. Ursodeoxycholic acid is suitable for treating cholesterol stones, hyperlipidemia, bile secretion disorders, primary biliary cirrhosis, chronic hepatitis, bile reflux gastritis, and preventing acute rejection and reactions of liver transplantation. The stone dissolving effect of this product is slightly weaker than that of chenodeoxycholic acid.
Production method
Method 1: Use chenodeoxycholic acid as raw materials
Preparation of 3α, 7α-diacetyl cholic acid methyl ester; Take 36ml of anhydrous methanol, and pass through 1g dried hydrogen chloride gas, add bile acid 12g, stir, heat and reflux for 20-30min. After standing for several hours at room temperature when crystals are separated out, freeze, filter, wash with ether, and dry to obtain methyl cholate. Take 2g methyl cholate, add 9.6 mL of benzene, 2.4mL pyridine, 2.4 mL of acetic anhydride, shake for 10-15min, stand for 20h at room temperature, then pour the reaction mixture into 100ml of water, remove the benzene layer, repeatedly wash with distilled water before recycling the solvents. Wash the solid residue with petroleum ether once, and re-crystallize with methanol-aqueous solution to obtain 3α, 7α-diacetyl bile acid methyl ester.
Bile acid methyl → → 3α, 7α-diacetyl bile acid methyl ester
Preparation of Chenodeoxycholic acid: Take the 1.5 g diacetyl bile acid methyl ester, add 24 mL acetic acid, add potassium chromate solution (Take 0.76g potassium chromate to dissolve it in 1.8ml take in water), heated to 40 °C, perform reaction for 8h, add water 120ml, shaking for some moment, placed 12h, filter, wash with distilled water till neutralization, dry to give 3α, 7α-diacetoxy-12-keto bile acid methyl ester, referred briefly as the 12-ketone. Take 12-15 g 12-ketone, add 150 mL 2-glycol ether, 15 mL 80% hydrazine hydrate solution, and 15 g potassium hydroxide. Heat to 30 °C and reflux for 15h, heat to 195-200 °C, refluxed for 2.5h, heat to 217 °C for some moment of reaction cool to 190 °C, add 0.7ml hydrazine hydrate solution, heat from within 215 °C to 220 °C within 3h, cool, add 600mL distilled water, adjust to pH 3 with 10% sulfuric acid, separate out the crystals, filter, wash with water until neutralization. Add ethyl acetate, dump the aqueous layer, use water to wash the organic layer was washed for 1-2 times, vacuum distillation and obtain 3α, 7α-dihydroxy cholanic acid, namely Chenodeoxycholic acid.
3α, 7α-diacetyl methyl cholate → 3α, 7α-diacetoxy-12-Keto ursodeoxycholic acid methyl ester → 3α, 7α-dihydroxy ursodeoxycholic acid (Chenodeoxycholic acid)
Preparation of refined ursodeoxycholic acid; Taken 2 g chenodeoxycholic acid, add 100ml of acetic acid and 20g potassium acetate, shake to dissolve. Add potassium chromate 1.5g (dissolved in 10 mL of water), at room temperature overnight, add water 200ml, separate out the crystals, filter, wash, and dry to obtain 3α-hydroxy-7-keto-ursodeoxycholic acid. Take 4g 3α-hydroxy-7-keto-ursodeoxycholic acid, add 100 mL n-butanol, heat to about 115 °C, gradually add 8 g metal sodium after which, white slurry gradually comes out, keep reaction for 30min, add 120ml water, stir and heat to transparently dissolve. Evaporate the organic layer under reduced pressure; add 500 mL water to the residue, dissolve, and filter. Adjust the pH the filtrate to pH 3 with 10% sulfuric acid which will yield white precipitate, filter, wash till neutralization with water, dry, wash with ethyl acetate, crystallize with diluted ethanol and obtain 3α, 7β-dihydroxycholanic acid, that’s refined ursodeoxycholic acid.
Chenodeoxycholic acid [potassium chromate] → 3α-hydroxy-7-keto acid [sodium metal, 115 °C] → 3α, 7β-Keto ursodeoxycholic acid methyl ester (Ursodeoxycholic acid)
Method 2: Use pig bile or bile salts as raw material; Use thin layer chromatography to isolate ursodeoxycholic acid from pigs bile or bile salt. Pig bile salt contains free and bound type of UDCA whose content is about 30%; pig bile contains bound UDCA whose content is about 0.6%.
