Comparative studies of bile salts. A new type of bile salt from Arapaima gigas (Cuvier) (family Osteoglossidae)

Abstract

1. Arapaima gigas bile salts were hydrolysed by alkali or cleaved with dioxan–trichloroacetic acid to give cholic acid, arapaimic acid, arapaimol-A and arapaimol-B. 2. I.r., n.m.r. and mass spectroscopy and [α]_D measurements indicated that arapaimic acid and arapaimol-A and -B are respectively 2α,3α,7α,12α-tetrahydroxy−5β,25∈-cholestan-26-oic acid, 5β,25R-cholestane-2β,3α,7α,12α,26-pentol and 5β-cholestane-2β,3α,7α,12α,26,27-hexol. 3. Partial synthesis of 2β,3α,7α,12α-tetrahydroxy−5α- and −5β-cholan-24-oic acid and their spectral examination fully confirmed these conclusions. 4. A. gigas bile salts show primitive features in that they comprise alcohol sulphates and a C₂₇ acid; they are also specialized in showing 2β-hydroxylation.