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A major purpose of this study was to examine inhibitory effect of the catechin derivatives from Japanese green tea Camellia sinensis on collagenase activity. The crude tea catechins, which contain (+)-catechin (C), (-)-epicatechin (EC), (+)-gallocatechin (GC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECg), and (-)-epigallocatechin gallate (EGCg), were tested for their ability to inhibit the prokaryotic and eukaryotic cell derived collagenase activities. Among the tea catechins tested, ECg and EGCg showed the most potent inhibitory effect on collagenase activity when an optimal concentration of tea catechins (100 micrograms/ml) was added to reaction mixture containing collagenase and collagen. Preincubation of collagenase with tea catechins reduced the collagenase activity as well. In contrast to ECg and EGCg, the other four tea catechins (C, EC, EGC, and GC) did not show any collagenase inhibitory effect. Our results suggest that the steric structure of 3-galloyl radical is important for the inhibition of collagenase activity. The collagenase activity in the gingival crevicular fluid from highly progressive adult periodontitis was completely inhibited by the addition of tea catechins. These results demonstrated that tea catechins containing galloyl radical possess the ability to inhibit both eukaryotic and prokaryotic cell derived collagenase.Makimura M, Hirasawa M, Kobayashi K, et al. Inhibitory effect of tea catechins on collagenase activity. J Periodontol 64:630-636; 1993. Green tea consumption and serum lipid profiles: a cross-sectional study in northern Kyushu, Japan.

Methods

The relation between green tea consumption and serum lipid concentrations was examined using cross-sectional data on 1,306 males who received the retirement health examination at the Self-Defense Forces Fukuoka Hospital between October 1986 and December 1988.

Results

After adjustment for rank, smoking, alcohol use, physical activity, and body mass index, serum total cholesterol levels were found to be inversely related to the consumption of green tea while no association was noted with serum triglycerides and high-density lipoprotein cholesterol. Adjusted mean concentrations of total cholesterol were 8 mg/dl lower in men drinking nine cups or more per day than in those consuming zero to two cups per day. Serum cholesterol levels were inversely associated with traditional Japanese dietary habits (intake of rice and soy bean paste soup) and positively associated with Westernized habits. Additional adjustment for these dietary variables did not alter the inverse relation between green tea and total cholesterol.Kono S, Shinchi K, Ikeda N, et al. Green tea consumption and serum lipid profiles: a cross-sectional study in northern Kyushu, Japan. Prev Med 21:526-531; 1992.