Effects of soaking temperature and soaking time during preparation of water extract of tea on anticlastogenicity against environmental tobacco smoke in the sister-chromatid exchange assay

Abstract

Water extract of tea (WET) was prepared by soaking green tea at different temperatures for various periods of time and was used to test whether the soaking temperature and soaking time during the preparation of WET influence the content of polyphenols and the anticlastogenicity of WET against environmental tobacco smoke (ETS). Five major polyphenols in WET were measured. Extractable–respirable particulate (ERP) was obtained from ETS-contaminated indoor air (ERP–ETS). The sister-chromatid exchange assay (SCE) was utilized to evaluate the clastogenic effects of ERP–ETS and the anticlastogenic effects of WET. The results indicate that ERP–ETS is clastogenic and WET has significant anticlastogenic effects on ERP–ETS. The content of polyphenols and the anticlastogenic potential of WET depended on the soaking temperature and soaking time during WET preparation. At the soaking temperature of 80°C, an increased soaking time was correlated with a higher percentage of polyphenols and a concomitantly enhanced anticlastogenic efficacy. By contrast, at the soaking temperature of 100°C, a longer soaking time was associated with a higher percentage of polyphenols concomitant with a lower anticlastogenic efficacy. The data suggest that, besides polyphenols, an additional material(s), which may be partially inactivated at 100°C, is contributing to the anticlastogenicity of WET.