In vitro and intracellular antioxidant capacity of thymyl methyl ether as a major component in Blumea lanceolaria (Roxb.) Druce leaf oil

Thymyl methyl ether is a major component of Blumea lanceolaria (Roxb.) Druce leaves. In this study, the antioxidant capacity of thymyl methyl ether and its better known hydroxylated form thymol was examined using oxygen radical absorption capacity and intracellular antioxidant capacity assays. Thymol displayed stronger peroxyl radical and hydroxyl radical-scavenging capacity, as well as reducing capacity than those of thymyl methyl ether, which can be explained by its hydrogen or electron donating capacity. However, thymyl methyl ether exhibited potent protection against peroxyl radical and Cu2+-induced oxidative stress when compared to thymol in the intracellular antioxidant capacity and lipid peroxidation assays using HepG2 cells. These results illustrate the higher cell membrane permeability of thymyl methyl ether to thymol and its transformation to thymol, which results in potent intracellular antioxidant capacity contributing to protection against lipid peroxidation.