Une M, Inoue A, Hoshita T
Institute of Pharmaceutical Sciences, Hiroshima University, School of Medicine, Japan.
Steroids. 1996 Nov;61(11):639-41. doi: 10.1016/s0039-128x(96)00137-7.
Varanic acid (3 alpha, 7 alpha, 12 alpha, 24-tetrahydroxy-5 beta-cholestanoic acid; 24-OH-THCA) is almost the sole component of bile acids in the bile of Bombina orientalis. To examine in the mechanism of the formation of 24-OH-THCA, radiolabeled (25R)- and (25S)-3 alpha, 7 alpha, 12 alpha-trihdroxy-5 beta-cholestanoic acids [(25R)- and (25S)-THCA] and (24E)-3 alpha, 7 alpha, 12 alpha-trihdroxy-5 beta-cholest-24-enoic acid (delta 24-THCA) were administered intraperitoneally to B. orientalis, gallbladder bile was collected after 24 h, and bile acids were subsequently extracted. Then the bile acids were analyzed by means of radio thin-layer chromatography and radio high-performance liquid chromatography after conversion to p-bromophenacyl ester derivatives. Although delta 24-THCA was not converted to 24-OH-THCA, (25R)-THCA and (25S)-THCA were transformed to (24R,25R)-24-OH-THCA and (24R,25S)-24-OH-THCA, respectively. These results strongly suggest that 24-OH-THCA was transformed via direct hydroxylation of the saturated side chain of THCA, not via hydration to an alpha, beta-unsaturated acid, delta 24-THCA, in B. orientalis.
变栖酸（3α，7α，12α，24 - 四羟基 - 5β - 胆甾烷酸；24 - 羟基 - 四氢胆酸）几乎是东方铃蟾胆汁中胆汁酸的唯一成分。为了研究24 - 羟基 - 四氢胆酸的形成机制，将放射性标记的（25R） - 和（25S） - 3α，7α，12α - 三羟基 - 5β - 胆甾烷酸[（25R） - 和（25S） - 四氢胆酸]以及（24E） - 3α，7α，12α - 三羟基 - 5β - 胆甾 - 24 - 烯酸（δ24 - 四氢胆酸）腹腔注射给东方铃蟾，24小时后收集胆囊胆汁，随后提取胆汁酸。然后将胆汁酸转化为对溴苯甲酰酯衍生物后，通过放射性薄层层析和放射性高效液相色谱进行分析。虽然δ24 - 四氢胆酸未转化为24 - 羟基 - 四氢胆酸，但（25R） - 四氢胆酸和（25S） - 四氢胆酸分别转化为（24R，25R） - 24 - 羟基 - 四氢胆酸和（24R，25S） - 24 - 羟基 - 四氢胆酸。这些结果有力地表明，在东方铃蟾中，24 - 羟基 - 四氢胆酸是通过四氢胆酸饱和侧链的直接羟基化形成的，而不是通过水合形成α，β - 不饱和酸δ24 - 四氢胆酸。
