Chan C K, Ulick S
Veterans Administration Hospital, Bronx, NY 10468.
J Steroid Biochem. 1989 Oct;33(4A):605-11. doi: 10.1016/0022-4731(89)90048-4.
The course of oxidative side chain cleavage of two recently isolated 17 alpha-hydroxy C-18 oxygenated naturally-occurring corticosteroids differed in that 18-hydroxycortisol yielded a 17-ketosteroid (Chu M. D., and Ulick S. (1982) J. biol. Chem. 257, 2218-2224) whereas 18-oxocortisol yielded a gamma-etiolactone (Ulick S., Chu M. D. and Land M. (1983) J. biol. Chem. 258, 5498-5502). In an analytic application of the periodic acid oxidative cleavage reaction to 18-oxocortisol, the finding of a second product of the reaction prompted a reinvestigation of its course. Both the delta 4,3-ketone secreted form of the steroid and its tetrahydro urinary metabolite were cleaved predominantly to 17-ketosteroids along with smaller amounts of gamma-etiolactones, whose proof of structure is herein reported. This anomalous course of oxidative cleavage was considered to reflect an equilibrium between C-20 ketone and cyclic-hemiketal forms in which the glycerol-type side chain structure of the later becomes the precursor of a 17-ketosteroid. Because of the similarities between in vitro oxidative side chain cleavage and in vivo corticosteroid metabolism, these findings suggest that C-18 oxygenated steroids may contribute to the 17-ketosteroid fraction of human urine.
最近分离出的两种17α-羟基C-18氧化天然存在的皮质类固醇的氧化侧链裂解过程有所不同，18-羟基皮质醇产生一种17-酮类固醇（朱医学博士和乌利克S.（1982年）《生物化学杂志》257，2218 - 2224），而18-氧代皮质醇产生一种γ-雌内酯（乌利克S.、朱医学博士和兰德M.（1983年）《生物化学杂志》258，5498 - 5502）。在对18-氧代皮质醇进行高碘酸氧化裂解反应的分析应用中，该反应第二种产物的发现促使对其过程进行重新研究。该类固醇的δ4,3-酮分泌形式及其四氢尿代谢物主要裂解为17-酮类固醇，同时伴有少量γ-雌内酯，本文报道了其结构证明。这种异常的氧化裂解过程被认为反映了C-20酮和环状半缩酮形式之间的平衡，其中后者的甘油型侧链结构成为17-酮类固醇的前体。由于体外氧化侧链裂解与体内皮质类固醇代谢之间的相似性，这些发现表明C-18氧化类固醇可能对人尿中的17-酮类固醇部分有贡献。
