On the peroxyl radical scavenging ability of β‐sitosterol in lipid media: A theoretical study

Abstract

AbstractVegetable consumption was considered healthy, mainly because a large number and variety of antioxidants were identified from them. However, the main component in all vegetables is β‐sitosterol, and although its antioxidant capacity was reported, little is known about the reaction mechanism involved. In this study, thermodynamic and kinetic studies of the peroxyl radical scavenging activity of β‐sitosterol in lipid media were carried out, employing the density functional theory (DFT). The results showed that the hydrogen transfer (HT) reaction mechanism is the most important in the peroxyl radical scavenging activity of β‐sitosterol when peroxyl radicals with a medium reactivity such as •OOH and •OOCH3 were considered. However, when the peroxyl radical has significant reactivity, it could react through the radical adduct formation (RAF) mechanism. The calculated overall reaction rate constants of the peroxyl radical scavenging of β‐sitosterol were 8.76 × 103 and 1.54 × 102 M−1 s−1 for the peroxyl radicals •OOH and •OOCH3, respectively. According to the previous results, β‐sitosterol might be considered a modest antioxidant, which prevents oxidative damage to biological molecules such as cell membrane lipids. These results support the idea that vegetables could be considered antioxidants in the organism, and therefore, considering the consumption of vegetables in the daily diet could prevent cell aging by inhibiting oxidative damage.