Thermal and Photooxidation Reactions of the Steroids : β-Sitosterol, Stigmasterol and Diosgenin

Abstract

Phytosterols β-sitosterol (1) and stigmasterol (2) were extracted from Nigella sativa which were collected from Al Qaseem’s area in the Kingdom of Saudi Arabia. Steroidal sapogenin diosgenin (3) was extracted from Balanites aegyptiaca (Zygopyllaceae), which was collected from Khamis al Bahr in theKingdom of Saudi Arabia. They have been fully characterized. Stigmasterol (2) and diosgenin (3) were acetylated to give stigmasterol and diosgenin acetate derivatives 4 and 5. Epoxidation of 1-5 gave exo and endo epoxide derivatives 6a, b; 10a, b; 11a, b; 16a, b and 17a, b as precursors of the brassinosteroidal compounds. On the other hand, photooxygenation of 1-5 gave hydroperoxysitosterol derivatives 7 and 9, hydroperoxystigmasterol derivatives 12 and 13, hydroperoxystigmasterol acetate derivatives 14 and 15, hydroperoxydiosgenin derivatives 18 and 19, and hydroperoxydiosgenin acetate derivatives 20 and 21.