Inhibitory effects of tannins on NADH dehydrogenases of various organisms.

We examined the effects of purified tannins and related compounds (33 species) on NADH-ubiquinone-1 oxidoreductase activity in four kinds of organism (Paracoccus denitrificans, Bacillus subtilis, Photobacterium phosphoreum, and Thermus thermophilus HB-8) and rat liver mitochondria. In addition to pentagalloylglucose, which was reported as a potent inhibitor of NADH dehydrogenases (NDH), sanguiin H-11, oolonghomobisflavan A, and polymerized procyanidin are potent inhibitors for both types of NDH (NDH-1 and NDH-2). We found that some other tannins contained in tea are also inhibitors of NDH from all organisms.