Mechanism of C-2 hydroxylation during the biosynthesis of 20-hydroxyecdysone in Ajuga hairy roots

Feeding synthetic [2 beta-H-2]- and [2 alpha-H-2]-cholesterols to the hairy roots of Ajuga reptans var. atropurpurea and LW-NMR analysis of the biosyn thesized 20-hydroxyecdysone revealed that hydroxylation at C-2 proceeds wit h retention of configuration. Feeding [2 alpha,3 alpha-H-2(2)]cholesterol f ollowed by H-2-NMR analysis of the 2,3,22-triacetate of the resulting 20-hy droxyecdysone ruled out a mechanism which involves a partial Loss of the 2 alpha-hydrogen. The steric course of C-2 hydroxylation in Ajuga hairy roots is Identical with that reported in the insect, Schistocerca gregaria.