Isolation and identification

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 mlz 544 and 528 which are shifted 30 mass units upfield compared to those (mlz 514 and 498) of taurocholate and taurochenodeoxycholate, 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. I 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. 'Hand I3C-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. --ne, M., T. Goto, K. Kihira, T. Kuramoto, K. Hagiwara, T. Nakajima, and T. Hoshita. Isolation and identification of bile salts conjugated with cysteinolic acid from bile of the red seabream, Pagrosomuc majm J. Lipid Res. 1991. 32: 1619-1623. Supplementary key words nodeoxycholic acid D-cysteinolic acid conjugated bile acids cholic acid cheThe red seabream, Pagrosomu major, is one of the most valuable and expensive fish in Japan, and the aquaculture of the marine teleost is under development in various districts ih the country. However, cultured red seabream is inferior in quality to the wild type, presumably because of differences in diet. In order to improve the quality of cultured red seabream, studies on nutrition especially lipid nutrition, of the cultured fish have been carried out extensively, but no information is available on the comparison of bile salts in wild and cultured fish. Bile salts play a very important role in lipid digestion and absorption. In this study, 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.