ABSTRACT
Peroxynitrite (ONOO-)-scavenging activities of nine Compositae herbs consisting of three Ixeris, two Youngia, two Cirsium and one of each Lactuca and Taraxacum species were evaluated. The contents of their ONOO- scavengers in the extracts were also determined on a HPLC using seven standard compounds, chlorogenic acid (CGA), chicoric acid (CA), luteolin 7-glucoside (luteolin-7-glc), luteolin 7-glucuronide (luteolin-7-glcU), luteolin, linarin and pectolinarin. Five of those compounds exhibited potent ONOO--scavenging activities: IC50, CA (0.76 microM), CGA (1.34 microM), luteolin (0.81 microM), luteolin-7-glc (0.86 microM) and luteolin-7-glcU (3.13 microM). Both CA and luteolin-7-glc were highly contained in I. dentata (19.71 mg/g and 13.58 mg/g, respectively), I. dentata var. albiflora (17.58 mg/g and 23.83 mg/g, respectively) and I. sonchifolia (65.71 mg/g and 6.99 mg/g, respectively). Among the nine herbs, those three Ixeris species had very low IC50 values over the range of 0.48 - 1.74 microg/mL, suggesting that they could be potential therapeutic vegetables, particularly for preventing diabetic complications or obesity, which can be caused by an excess production of ONOO-.