Biosynthesis of yamogenin, neotokorogenin, and their (25R)-isomers from [1,2-13C2]acetate in Dioscorea tokoro tissue cultures

Abstract

In the biosynthesis of (25S)-steroidal sapogenins in tissue cultures of Dioscorea tokoro Makino fed with sodium [1, 2-¹³C₂] acetate, the ¹³C n.m.r. spectra of the ¹³C-labelled (25 S)-sapogenins (3) and (4) indicated (i) that a hydrogen atom at C-25 was introduced from the 25-si face of the Δ²⁴ double bond of Δ²⁴-biosynthetic intermediates as in the case of the (25R)-sapogenins (1) and (2), and (ii) that oxidation of the pro-R methyl group (C-26) of cholesterol was accelerated by a higher concentration of sodium acetate giving (25S)-steroidal sapogenins.