Scavenging of Nitrite and Inhibition of Nitrosamine Formation by Laoying Tea (Litsea coreana L.) Extracts

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.