Biosynthesis of makisterone A and 20‐hydroxyecdysone from labeled sterols by the honey bee, <i>Apis mellifera</i>

Abstract

Abstract In an effort to determine the sterol precursor(s) of the 28‐carbon ecdysteroid, makisterone A, honey bee pupae (13 days post‐oviposition) were injected with radiolabeled sterols and subsequently examined for labeled ecdysteroids. High performance liquid chromatography of the pupal extracts revealed that [ 3 H]campesterol was converted to a compound that behaved chromatographically identical to authentic makisterone A, and [ 14 C]cholesterol was incorporated into a compound chromatographically like 20‐hydroxyecdysone. No incorporation of either 24‐[ 3 H]methylenecholesterol or [ 14 C]sitosterol into an ecdysteroid was observed. The neutral sterols of uninjected honey bee pupae contained 49.8% 24‐methylenecholesterol on a relative percent basis and, with three other C 28 and C 29 sterols, accounted for over 99% of the total sterols present.