Papers by Author: Yuan Zhang

Abstract: The petroleum ether, acetic ester, methanol and water extracts of laoying tea were prepared and their antioxidant properties were studied. At 160 µg/mL, the methanol extract showed a high reducing power of 1.206. With regard to the scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radicals, extracts were effective in the order: methanol > acetic ester > water > petroleum ether extracts. EC₅₀ values for chelating ability on ferrous ions for petroleum ether, acetic ester, methanol and water extracts were 11.76, 14.32, 6.05 and 1.02 mg/mL, respectively. Based on EC₅₀ values, the various extracts from laoying tea were effective antioxidants.

Abstract: 50% (V/V) ethanol extract from laoying tea (Litsea coreana Level.) was fractionated by liquid-liquid partition using ethyl acetate, n-butanol and water, respectively. The activities of nitrite scavenging (NS) and nitrosamine formation inhibiting (NFI) of three different fractions have been investigated in vitro systems. In the above assays, all the fractions showed NS and NFI potentials to varying degrees. With regard to NS activity, fractions were effective in the order: ethyl acetate > n-butanol > water fraction. EC₅₀ values for inhibiting ability on nitrosamine formation for ethyl acetate, n-butanol and water fraction were 0.170, 0.554 and 0.725 mg/mL, respectively. Total flavonoids could be the major NS and NFI components and were in the order: ethyl acetate > n-butanol > water fraction. Based on EC₅₀ values, laoying tea especially ethyl acetate-soluble fraction may have a preventive effect against carcinogenesis induced by nitrosamines.

Abstract: Chroogomphis rutillus is an ectomycorrhizal edible mushroom available in China. The ethanolic, cold water and hot water extracts were prepared and their antioxidant properties studied. At 4 mg/mL, the ethanolic extract showed a high reducing power of 1.561, whereas those of cold water and hot water extracts were 1.161 and 0.808. With regard to the scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radicals, extracts were effective in the order: ethanolic > cold water > hot water extracts. EC₅₀ values for chelating ability on ferrous ions for ethanolic, cold water and hot water extracts were 15.755, 0.059, and 0.067 mg/mL, respectively. Based on EC₅₀ values, the various extracts from C. rutillus were effective antioxidants.