2,3-Epoxybrassinosteroids are intermediates in the biosynthesis of castasterone in seedlings of Secale cereale

A brassinosteroid biosynthetic pathway from teasterone/typhasterol via 2,3-epoxybrassinosteroids to castasterone has been found in seedlings of Secale cereale. Epoxide hydrolysis resulting in stereoisomeric vicinal 2,3-diols followed by inversion of configuration at C-2 and C-3 was demonstrated by stepwise administration of deuterated precursors and HPLC-ESI-MS-SIM detection.