Photooxygenation of β-sitosterol and stigmasterol and DNA-damaging properties of their hydroperoxide products

Abstract

The phytosterol β-sitosterol (1), its acetate derivative (3) and stigmasterol (2) were photo-oxygenated using tetraphenyl porphorin (TPP) or rose Bengal (RB) and sensitizer in different solvents to give hydroperoxides 4,8 and dihydroperoxide 7, respectively. Structures 4,8 and 7 were elucidated on the basis of spectral data from their 1H NMR, MS and IR spectra. Product 7 produced moderate DNA degradation, but 4 did not.