Isolation and identification of bile salts conjugated with cysteinolic acid from bile of the red seabream, Pagrosomus major.

M Une,T Goto,K Kihira,T Kuramoto,K Hagiwara,T Nakajima,T Hoshita

doi:10.1016/s0022-2275(20)41647-5

Abstract

Bile salts present in gallbladder of wild and cultured red seabream, Pagrosomus major, a marine teleost were analyzed. The bile from wild red seabream was found to contain two previously unknown bile salts along with two known bile salts, taurocholate and taurochenodeoxycholate. Isolation of each bile salt was performed by column chromatography. Fast atom bombardment mass spectra of the unknown bile salts showed the molecular ions (M-H)- of m/z 544 and 528 which are shifted 30 mass units upfield compared to those (m/z 514 and 498) of taurocholate and taurochendeoxycholate, respectively; this is consistent with the presence of cysteinolic acid (mol wt 155) instead of taurine (mol wt 125). Enzymatic hydrolysis of the bile salts released cholic acid and chenodeoxycholic acid, respectively, and an amino acid that was identified as D-cysteinolic acid by direct comparison with an authentic sample. From these results, the bile salts in the bile of wild red seabream were identified as the conjugates of cholic acid and chenodeoxycholic acid with cysteinolic acid. 1H- and 13C-magnetic resonance spectra of the bile salts were also consistent with the proposed structure. The cysteinolic acid conjugates were found only in wild and not in cultured red seabream; this distinction seems to result from differences in dietary cysteinolic acid.

Highlights

Bile salts present in gallbladder of wild and cultured red seabream, Pagrosomus major, a marine teleost were analyzed
We report the chemical structure of the bile salts of wild and cultured red seabream; we found D-cysteinolic acid-conjugated cholic and chenodeoxycholic acids only in wild and not in cultured red seabream
Since the measurement of the optical rotation could not be performed because of the insufficient amount of the amino acid obtained after hydrolysis of bile salt 1, the chirality was determined by chiral monitoring

Summary

Introduction

Bile salts present in gallbladder of wild and cultured red seabream, Pagrosomus major, a marine teleost were analyzed. We report the chemical structure of the bile salts of wild and cultured red seabream; we found D-cysteinolic acid-conjugated cholic and chenodeoxycholic acids only in wild and not in cultured red seabream. Crude bile salts (4.5 g) were obtained from 12 cultured red seabream. The crude bile salts were chromatographed on a column of silica gel using a mixture of chloroformmethanol-acetic acid-water 13:4:2:1 (by vol) as an eluting solvent.

Results

Conclusion