Mechanism of Anti-obese Effects of ‘Benifuuki’ Green Tea

Abstract

The molecular mechanism underlying high anti-obese effects of ‘benifuuki’, a tea cultivar that contains unique methylated catechins such as epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3”Me), was explored. This cultivar was then compared with ‘yabukita’, a popular tea cultivar that lacks these methylated catechins. (1) The comprehensive gene expression in the perirenal adipose tissue of mice (12-week-old male C57BL/6J) was examined by DNA microarray analysis, following consumption of either high-fat diets with and without the addition of 2% benifuuki or 2% yabukita leaf powder. (2) In cultured 3T3-L1 cells, EGCG, EGCG3”Me and caffeine were compared for their inhibitory effects on the intracellular fat accumulation as well as on cell differentiation from precursor to mature adipocytes. (3) Time-dependent changes in EGCG and EGCG3”Me plasma concentrations were examined in catheterized rats following oral administration of benifuuki extract under an overnight fasting condition. The results of the DNA microarray indicated that the anti-obese effect of benifuuki may be ascribed to the inhibition of fat accumulation in adipocytes via the downregulation of enzyme expression associated with both the synthesis and β-oxidation of fatty acids. The stronger anti-obese effects of benifuuki compared with yabukita may be attributed to the presence of its unique methylated catechins (primarily EGCG3”Me), whose stability in circulation is 3.2 times higher than EGCG ; however, the inhibitory activity of EGCG3”Me on fat accumulation is almost the same as that of EGCG (about 91% in terms of differentiation inhibition in 3T3-L1 cells). Thus, EGCG3”Me appears to fortify the overall anti-obese effects of benifuuki. That is, the inhibitory activity on fat accumulation through the combination of both EGCG and EGCG3”Me was 1.7 times higher than that through EGCG alone, even though the content of EGCG3”Me in benifuuki is much less than EGCG.