Characterization of oxyphytosterols generated by β-sitosterol ozonization.

Abstract β-Sitosterol (βSito) is the most abundant phytosterol found in elevated concentrations in vegetable oils, nuts, seeds, cereals, fruits, and in many phytosterol-enriched foods. Although the benefits, there is a concern in terms of food quality and health due to the increasing consumption of phytosterols and the possible adverse side effects of their oxidation products, oxyphytosterols. βSito has a similar structure to cholesterol, with an unsaturated double bond at C5–C6, which is susceptible to oxidation by reactive oxygen species like ozone, generating oxyphytosterols. In this work we propose a mechanism of formation of three oxyphytosterols 2-[(7aR)-5-[(1R,4S)-4-hydroxy-1-methyl-2-oxocyclohexyl]-1,7a-dimethyl-1,2,3,3a,4,5,6,7- octahydroinden-4-yl]acetaldehyde (βSec), (2-[(7aR)-5-[(2R,5S)-5-hydroxy-2-methyl-7-oxo-oxepan- 2-yl]-1,7a-dimethyl-1,2,3,3a,4,5,6,7-octahydroinden-4- yl] acetaldehyde (βLac) and 2-((7aR)-5-((1R,4S)-4-hydroxy-1-methyl-2- oxocyclohexyl)-1,7a-dimethyloctahydro-1Hinden-4-yl) (βCOOH) generated by ozonization of βSito, through their synthesis and molecular characterization. The cytotoxic effect of βSito and its main oxyphytosterol βSec was evaluated and both reduced the HepG2 cell viability.