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

Feeding synthetic [2beta-2H]- and [2alpha-2H]-cholesterols to the hairy roots of Ajuga reptans var. atropurpurea and 2H-NMR analysis of the biosynthesized 20-hydroxyecdysone revealed that hydroxylation at C-2 proceeds with retention of configuration. Feeding [2alpha,3alpha-2H2]cholesterol followed by 2H-NMR analysis of the 2,3,22-triacetate of the resulting 20-hydroxyecdysone ruled out a mechanism which involves a partial loss of the 2alpha-hydrogen. The steric course of C-2 hydroxylation in Ajuga hairy roots is identical with that reported in the insect, Schistocerca gregaria.