Bosch R, Visser W J, Thijssen J H, Duursma S A
J Steroid Biochem. 1983 Apr;18(4):441-7. doi: 10.1016/0022-4731(83)90063-8.
Dihydrotachysterol2 (DHT2), a 5,6-trans derivative of vitamin D2, is very successfully used in the treatment of hypoparathyroidism and renal osteodystrophy. However, the metabolism and the action of DHT2 are poorly understood. Investigations into metabolism of DHT2 start at the synthesis of the radioactively labelled compound. This paper deals with a two-step synthesis of [10S(19)-3H]-dihydrotachysterol2 from vitamin D2. Vitamin D2 can be converted into 5,6-trans vitamin D2 by iodination under irradiation and by triplet-sensitized isomerization. The first method led to unwanted side-reaction products which were difficult to separate from 5,6-trans vitamin D2. Triplet-sensitized isomerization yielded merely 5,6-trans vitamin D2 which could be separated from the residual starting material by chromatography on silica gel and recrystallization. 10S-3H]-Dihydrotachysterol2 with a specific radioactivity of 56 kCi/mol was prepared from 5,6-trans vitamin D2 via partial, homogeneous catalytic reduction of the 10S(19) double bond with tritium gas. It was purified by high-performance liquid chromatography (h.p.l.c.) and characterized by chromatography and ultra-violet absorption spectrophotometry. The biological usefulness of the material was demonstrated in rats following intragastric administration. Blood was collected after 24 and 48 h and fractionation of serum lipids on h.p.l.c. showed 5 peaks of radioactivity.
二氢速甾醇2（DHT2）是维生素D2的5,6 - 反式衍生物，在甲状旁腺功能减退症和肾性骨营养不良的治疗中得到了非常成功的应用。然而，人们对DHT2的代谢和作用了解甚少。对DHT2代谢的研究始于放射性标记化合物的合成。本文介绍了从维生素D2两步合成[10S(19)-3H]-二氢速甾醇2的方法。维生素D2可通过辐射碘化和三重态敏化异构化转化为5,6 - 反式维生素D2。第一种方法会产生不需要的副反应产物，这些产物很难与5,6 - 反式维生素D2分离。三重态敏化异构化仅产生5,6 - 反式维生素D2，可通过硅胶柱色谱和重结晶从残留的起始原料中分离出来。通过用氚气对10S(19)双键进行部分均相催化还原，由5,6 - 反式维生素D2制备出比活度为56 kCi/mol的10S-3H]-二氢速甾醇2。通过高效液相色谱（h.p.l.c.）对其进行纯化，并通过色谱和紫外吸收分光光度法对其进行表征。在大鼠经胃内给药后证明了该物质的生物学效用。在24小时和48小时后采集血液，通过h.p.l.c.对血清脂质进行分级分离显示有5个放射性峰。
