期刊名称：Journal of Nutritional Science and Vitaminology
印刷版ISSN：0301-4800
电子版ISSN：1881-7742
出版年度：2016
卷号：62
期号：2
页码：134-138
DOI：10.3177/jnsv.62.134
出版社：Center for Academic Publications Japan
摘要：Green tea is thought to be a primary source of folate in the Japanese diet, based on folate content analyzed by a microbiological assay. Green tea also contains high amount of catechins, in particular, epigallocatechin gallate (EGCg), which was demonstrated to be able to inhibit the digestive enzyme activities and microbial growth in the folate assay. In the present study, we examined whether tea catechins interfered with components of the folate assay for green tea. A marked inhibitory effect of EGCg on microbial growth was observed at an inhibitory concentration of higher than 10 μg/mL. Tea catechins without the galloyl moiety did not show an inhibitory effect. EGCg inhibited the activity of the three enzymes used for assay sample preparation at an inhibitory concentration of higher than 750 μg/mL for α-amylase, 1,000 μg/mL for protease, and 50 μg/mL for conjugase. However, with each step of the assay, the actual concentration of EGCg was decreased to below the inhibitory concentration of each analytical step. Lack of influence of EGCg on green tea folate assay was confirmed by an addition of folate standard in tea infusion. These results suggested that tea catechins have no practical impact on folate analysis in green tea, using the general microbiological assay.
