Antioxidant effects of Origanum majorana L. on superoxide anion radicals

A purified compound with antioxidant properties (28 mg), T3b, was isolated from a methanol extract (10 g) of Origanum majorana L. by sequential procedures, with silica gel column, thin-layer, and LH-20 Sephadex gel column chromatographies. The in vitro scavenging activity of T3b on superoxide anion radical (O2−) was investigated and compared to those of seven commercially available synthetic or natural antioxidants. Of those, the strongest scavenging action was observed in T3b with an IC50 of 1.44 μg/ml. The T3b also exhibited significant inhibitory effects on 12-O-tetradecanolyphorbol-13-acetate (TPA)-induced O2− generation and hydrogen peroxide formation in differentiated HL-60 cells, indicating that the isolated compound is a potent chemopreventer. The purified compound from O. majorana L. was shown to possess both O2− scavenging activity and an inhibitory effect against TPA-induced O2− generation.