Antioxidant Activity, Inhibition of No Production and Cytotoxicity of Chemical Compounds Isolated from Oxalis corniculata L.

Five flavonoid compounds were isolated from ethyl acetate extract of the aerial part of Oxalis corniculata L. and identified as: 4 ',5,7-trihydroxy-6-methoxyisoflavon (tectorigenin 1), 3 ',5,7-trihydroxy-4 ',5 ',6-trimethoxyisoflavon (irigenin 2), 4 ',5,7-trihydroxy-3 ',6-dimethoxyisoflavon (iristectorigenin A 3), kaempferol-3,7-di-O-alpha-L-rhamnopyranosid (kaempferitrin 4), and kaempferol-3-O-alpha-L-rhamnopyranosyl-(1 -> 2)-alpha-Larabinofuranosid (arapetaloside B 5). All the isolated compounds showed potential antioxidant effects in DPPH radical scavenging activity test with IC50 values in the range from 28.62 to 48.53 mu g/mL, varied in following order: compound 1 > 3 > 2 > 5 > 4. The five phytochemicals produced inhibition of nitric oxide (NO) production, with IC50 values ranging from 18.6 to 39.5 mu M. All isolated compounds exhibited cytotoxicity against HepG2, LU-1, MCF-7 and SK-Mel-2 cells using Sulforhodamine B assay, with IC50 values in the range ftom 12.32 to 39.88 mu M.