Protective effects of solvent extracts from Taiwanese Agrocybe cylindracea strain B against DNA damage induced by environmental mutagens

Antioxidant activity of a water extract from Agrocybe cylindracea strain B (ACB) against iron-mediated lipid peroxidation has been demonstrated. In addition, the protective effect of water extracts from ACB (WAC) on hydroxyl radical-mediated DNA strand breaks was better than that of the shiitake mushroom (Lentinula edodes). Therefore, we decided to investigate whether different solvent extracts from ACB (ACES) protect DNA against oxidative stress induced by environmental mutagens, such as cooking oil fumes (COF) and benzo[a]pyrene (BaP). Oxidative DNA damage and intercellular DNA migration (tail length) were quantified by determining the decrease of extracellular supercoiled (SC) plasmid DNA and by using the 'comet assay' in the human adenocarcinoma CL-3 cell line, respectively. IC₅₀ values of water, boiled water, methanol and acetone extracts from ACB were 108.97, 87.21, 970.52 and 1005.87 μg mL ^-1, respectively, for the decrease in cupric/COF-mediated SC plasmid DNA damage. The boiled water extract has the best protective effect. The ethyl acetate and ether extracts did not inhibit plasmid DNA damage. By using the comet assay, IC₅₀ values of the ether, methanol and acetone extracts from ACB were 672.95, 64.34, and 397.77 μg mL^-1, respectively, for the decrease in COF-mediated DNA migration in CL-3 cells. The methanol extract had the best protective effect. However, water, boiled water and ethyl acetate extracts from ACB showed no protective effect on COF-mediated DNA migration. These results indicate that the protective capacity of ACES on DNA damage induced by environmental mutagens is different in pUC18 plasmid DNA and CL-3 cell DNA.