Biosynthesis of 20-hydroxyecdysone in Ajuga hairy roots: the possibility of 7-ene introduction at a late stage

Abstract

Administration of [3α- 2 H ]-3β-hydroxy-5β-cholestan-6-one to hairy roots of Ajuga reptans var. atropurpurea followed by 2 H -NMR spectroscopic analysis of the resulting 20-hydroxyecdysone so formed revealed that the substrate was efficiently incorporated into the latter. Additionally, [5β,7α,7β- 2 H 3 ]-2β,3β-dihydroxy-5β-cholestan-6-one was converted into 20-hydroxyecdysone. These findings clearly indicate that Ajuga hairy roots are capable of introducing a double bond at the 7-position at a late stage of 20-hydroxyecdysone biosynthesis, suggesting the possibility of an alternative biosynthetic pathway which does not involve 7-dehydrocholesterol as an obligatory intermediate.