Biosynthesis of 20-hydroxyecdysone in plants: 3β-Hydroxy-5β-cholestan-6-one as an intermediate immediately after cholesterol in Ajuga hairy roots

3β-Hydroxy-5β-cholestan-6-one was characterized as an early-step intermediate for 20-hydroxyecdysone biosynthesis in Ajuga hairy roots. 2H-labeled cholesterol was converted to the ketone with migration of the hydrogen atom from C-6 to C-5. The ketone was suggested to be an intermediate immediately after cholesterol in this plant.150