Antioxidative constituents from Lycopus lucidus

Three phenolic compounds, rosmarinic acid (1), methyl rosmarinate (2), ethyl rosmarinate (3), and two flavonoids, luteolin (4), luteolin-7-O-beta-D-glucuronide methyl ester (5) were isolated from the aerial part of Lycopus lucidus (Labiatae). Their structures were determined by chemical and spectral analysis. Compounds 1-5 exhibited potent antioxidative activity on the NBT superoxide scavenging assay. The IC50 values for compounds 1-5 were 2.59, 1.42, 0.78, 2.83, and 3.05 mug/mL respectively. In addition, five compounds were isolated from this plant for the first time.