Biol. Pharm. Bull. 28(6) 963—966 (2005)

of different kinds of diseases, including aging, coronary heart disease, inflammation, stroke, diabetes mellitus, rheumatism, liver disorders, renal failure and cancer. Reactive oxygen species (ROS) comprise free radicals such as · O2 (superoxide anion), · OH (hydroxyl radical), H2O2 (hydrogen peroxide) and O2 (singlet oxygen), which can cause cellular injuries and also initiate peroxidation of polyunsaturated fatty acids in biological membranes. The tissue injury caused by ROS include DNA damage, protein damage and oxidation of enzymes in the human body. Antioxidants such as a-tocopherol is capable of mitigating free radical damage and scavenging ROS. Enzymatic antioxidants include superoxide dismutase (SOD), catalase and glutathione peroxidase (GPX), whereas non-enzymatic antioxidants comprise a-tocopherol, bcarotene, carotenoids, chlorophylls, flavonoids, tannin and certain micronutrients (e.g. zinc and selenium). The present of these antioxidants in the cellular system are known to prevent oxidative damage. Thus, a number of antioxidants derived from plants such as Ginkgo biloba, Prunella vulgaris, Therminalia chebula, Cinnamomum cassia. have been widely studied. Dietary intake of antioxidants has been increasingly accepted as a strategy for maintaining a healthy life. P. peruviana is a medicinal plant widely used in folk medicine as anticancer, antimycobacterial, antipyretic, immunomodulatory, and for treating diseases such as malaria, asthma, hepatitis, dermatitis, diuretic and rheumatism. Hot water extract of P. peruviana (HWEPP) is often used to prepare health beverages. However, it remains unknown if HWEPP and extracts prepared from different concentrations of ethanol possess antioxidant activity. In this study, our objective was to evaluate the antioxidant activities of HWEPP and extracts prepared from 20, 40, 60, 80 and 95% ethanol of whole plant of P. peruviana. Its antioxidant activities were also compared with a well known natural antioxidant, a-tocopherol.