14B-28

L. M. CHEUNG, Department of Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China and P. C. -. K. Cheung.

Lipid oxidation has been a problem in daily life. It not only brings about unpleasant flavor in foods but also produces harmful reactive oxygen species, which lead to carcinogenesis, mutagenesis, and aging. Antioxidant is known to prevent or delay the onset of the oxidation. There is increasing evidence showing that antioxidant may have some properties in preventing free-radical generating diseases such as cardiovascular disease and cancer. One of the sources of antioxidants comes from food. Previous studies have shown that mushrooms possess some antioxidative activity. The objective of this study was to assess the antioxidative activity of extracts from three Oriental mushrooms. Aqueous extracts from three mushrooms (Lentinus edodes, Volvariella volvacea and Pleurotus tuber-regium) were tested for their antioxidant activity by one chemical assay (beta-carotene bleaching method) and two biological assays (hemolysis of red blood cells from rats and lipid peroxidation of brain tissue from rats). Our preliminary results showed that all the mushroom extracts inhibited lipid oxidation to various extents (percentage of inhibition from 56% to 95%). The antioxidant activity coefficient (AAC) (which defines as {[A_s(120)-A_c(120)]/[A_c(0)-A_c(120)]}x1000, where A_s(120) was the absorbance of the antioxidant mix at t=120 min, A_c(120) the absorbance of the control at t=120 min, and A_c(0) the absorbance of the control at t=0 min. ) of the mushroom extracts varied with different concentrations (from 639 in 1mg/ml to 815 in 10mg/ml) and extraction temperatures (500 at room temperature and 804 at 100¢J). These findings may suggest that mushroom is a potential source of natural antioxidant and further studies are needed to identify the active components in these extracts.