Nonenzymatic antioxidative and antiglycative effects of oleanolic acid and ursolic acid.

Oleanolic acid and ursolic acid are two triterpenes presented in several herbs. This study analyzed the content of oleanolic acid and ursolic acid in eight locally available fresh herbs, also examined several nonenzymatic antioxidant activities of these two triterpenes, and used a liposome system to evaluate the influence of temperature and pH upon the antioxidant property of these two triterpenes. The impact of these two triterpenes on the production of nonenzymatic glycative products, pentosidine and carboxymethyllysine (CML), was also evaluated. alpha-Tocopherol was used for comparison. Results showed that the content of oleanolic acid and ursolic acid in glossy privet fruit and hawthorn fruit varied from season to season and was in the range of 200-650 microg/g of fresh weight. Both oleanolic acid and ursolic acid possessed greater antioxidant activity against 2,2'-azobis-(2-amidinopropane) dihydrochloride and less antioxidant activity against 2,2'-azobis(2,4-dimethylvaleronitrile) when compared with alpha-tocopherol at equal concentration (P <0.05). At 75 and 100 degrees C, oleanolic acid exhibited greater antioxidant activity than alpha-tocopherol and ursolic acid (P <0.05). At pH 2 and pH 4, oleanolic acid and ursolic acid showed greater antioxidant activity than alpha-tocopherol (P <0.05). These two triterpenes also exhibited a dose-dependent effect in superoxide anion scavenging activity, chelating effect, xanthine oxidase inhibition activity, and reducing power (P <0.05). Oleanolic acid significantly and dose-dependently inhibited pentosidine and CML formation (P <0.05). Ursolic acid also significantly suppressed CML formation (P <0.05). These data support that these two triterpenes possessed nonenzymatic antioxidative and antiglycative properties.