Metabolism of C26 bile alcohols in the bullfrog, Rana catesbeiana

Metabolism of C26 bile alcohols in the bullfrog, Rana catesbeiana, was studied. 24-14C]-24-Dehydro-26-deoxy-5 beta-ranol (3 alpha,7 alpha,12 alpha-trihydroxy-27-nor-5 beta-cholestan-24-one) was chemically synthesized from 24-14C]cholic acid and incubated with bullfrog liver homogenate fortified with NADPH. 24-Dehydro-26-deoxy-5 beta-ranol was shown to be converted into both 26-deoxy-5 beta-ranol and 24-epi-26-deoxy-5 beta-ranol (24S)- and (24R)-27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24-tetrols] in addition to 5 beta-ranol (24R)-27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,26-pentol], which is the major bile alcohol of the bullfrog. 24-3H]-26-Deoxy-5 beta-ranol and 24-3H]-24-epi-26-deoxy-5 beta-ranol were prepared from 24-dehydro-26-deoxy-5 beta-ranol by reduction with sodium 3H] borohydride and administered respectively to two each of four bullfrogs by intraperitoneal injection. After 24 h, labeled 5 beta-ranol was isolated from the bile of the bullfrogs that received 24-3H]-26-deoxy-5 beta-ranol. In contrast little if any radioactivity could be detected in 5 beta-ranol or its 24-epimer after administration of 24-3H]-24-epi-26-deoxy-5 beta-ranol.