Tea polyphenols as novel and potent inhibitory substances against renin activity.

Renin inhibitory activities of three tea products were investigated for the first time in this work. Water extracts from fermented oolong and black tea showed strong renin inhibitory activities. By the means of ultrafiltration, gradient high performance liquid chromatography and spectroscopic analysis, four active compounds were separated from aqueous black tea extract and identified as theasinensin B, theasinensin C, strictinin, and a hexose sulfate with a galloyl moiety, which had IC50 values of 19.33, 40.21, 311.09, and 50.16 μM against renin activity, respectively. Further detection indicated that the potent inhibitor theasinensin B was present only in black tea, and that monomeric catechins did not contribute significantly to the renin inhibitory activities of tea products. These results revealed novel and potent tea-derived renin inhibitors and suggested another potential pathway for tea consumption to control hypertension.