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

Administration of 3alpha-2H]-3beta-hydroxy-5beta-cholestan-6-one to hairy roots of Ajuga reptans var. atropurpurea followed by 2H-NMR spectroscopic analysis of the resulting 20-hydroxyecdysone so formed revealed that the substrate was efficiently incorporated into the latter. Additionally, 5beta,7alpha,7beta-2H3]-2beta,3beta-dihydroxy-+ ++5beta-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.