Antioxidative and antimicrobial effects of water extracts with Castanea crenata leaf tea

摘要

Antioxidative and antimicrobial effects of the extracts of Castnaea crenata leaf tea, steamed tea and semi-fermented tea were investigated. Antioxidative effects were by measuring the l,l-diphenyl-2-picrylhydrazyl (DPPH)-radical scavening activity of the extracts. The effects were stronger than that of synthetic antioxidant such as BHT at the same concentration. The SC_(50) value (50% radical scavening effects of 1 X 10~(-4) M DPPH) of steamed tea, semi-fermented tea and BHT were 53.3 #mu#g/mL, 49.9 #mu#g/mL and 101.0 #mu#g/mL, respectively. The antimicrobial effects of methanol extracts (8 mg, 20 mg) of 0.2 g and 0.5 g. eq. of Castnaea crenata leaf tea were stronger than those of 0.65 mg of benzoic acid, against gram(+) bacteria such as S. aureus, S. epidermidis, M. luteus, L. mesenteroides and B. subtilis and gram(-) bacteria such as E. coli, S. typhimurium, and P aeruginosa.