Bile acids and bile alcohols from Muraenesox bagio, Pomadasys argenteus and Lobeo rohita

Gallbladders bile of three well known commercial fish of South Asia region named Muraenesox bagio (locally called bam), Pomadasys argenteus (dother) and Lobeo rohita (rohu) were analysed on GC-MS, after derivatising the bile alcohols and bile acids as trimethylsilyl ether and trimethylsilyl-methyl ester, respectively. Cholic acid (1) and chenodeoxycholic acid (2) were found as major bile acids in all three species. Major bile alcohol in these fish was cholesterol (4), which was not detected in freshwater specie (L. rohita). M. bagio was also found to contain 3αα,7α,12α-trihydroxy-23-cholesten-26-oic acid (3). Other bile acids and bile alcohols identified in L. rohita were allo deoxycholic acid (5), 12-oxo-3α-hydroxycholanic acid (6), 3α,7α,12α-trihydroxy-24-cholesten-26-oic acid (7), 5α- and 5β-anhydrocyprinol (8 and 9, respectively) and 5β-homocholane-3α,7α,12α-25-tetrol (10). Besides acting as emulsifying agent in the digestion process, in non-mammalian vertebrates, e.g., fish, reptiles, etc. the analytical and elucidative studies on the bile contents disclose the diversity in metabolic pathways of cholesterol and indicate the existence of molecular evolution in the basic C skeleton of cholesterol.