Phenolic compounds from Eurycorymbus cavaleriei

Three new phenolic compounds, eurycorymboside A (1), eurycorymboside B (6), and eurycorymbic acid (8), were isolated from the stem part of Eurycorymbus cavaleriei (Sapindaceae) along with five known phenolic compounds, glucosyringic acid (2), vanillic acid 4-O-β-d-glucoside (3), koaburaside (4), tachioside (5), and 4-hydroxy-3,5-bis(3-methyl-2-butenyl)benzaldehyde (7). The structures were established on the basis of spectral analysis. The antioxidant activities of compounds 1-6 were evaluated by the 1,1-diphenyl-2-picrylhydrazyl-free radical scavenging assay. Compound 4 exhibited antioxidant activity with an IC(50) value of 9.0 μM. Compound 4 also showed weak inhibitory activity against influenza A neuraminidase.