Biliary bile acids of fruit pigeons and doves (Columbiformes): presence of 1-beta-hydroxychenodeoxycholic acid and conjugation with glycine as well as taurine.

Abstract

The biliary bile acid composition of 30 species of pigeons and doves belonging to seven genera in the avian order Columbiformes was determined using TLC, HPLC, GLC/MS, LSIMS, and NMR. In 23 of 25 species of fruit pigeons and doves, chenodeoxycholic acid was the major bile acid (> 50%). In only 1 species (Ptilinopus ornatus) was cholic the major bile acid. A number of species (7 of 15 species in the genus Ptilinopus, and 6 of 9 species in the genus Ducula) contained 1 beta,3 alpha,7 alpha-trihydroxy-5 beta-cholan-24-oic acid in proportions ranging from 2 to 43%. This 1 beta-hydroxy derivative of chenodeoxycholic acid has not been previously identified as a major biliary bile acid in vertebrates. Five of 15 species of the genus Ptilinopus, 5 of 9 species of the genus Ducula, and the only species examined for the genus Gymnophaps contained 23R-hydroxy chenodeoxycholic acid in detectable proportions, ranging from 1 to 4%. Bile acids were conjugated (in N-acyl linkage) with glycine and taurine in 28 species and with only taurine in 2 species. The fruit pigeons are the first non-mammalian genera identified to date in whom bile acids are conjugated with glycine, as well as with taurine. An incidental finding was that a gallbladder was present in 3 genera (Ptilinopus, Ducula, and Gymnophaps) and absent in 4 genera (Gallicolumba, Chalcophaps, Otidiphaps, and Treron).