Both non-covalent and covalent interactions were involved in the mechanism of detoxifying effects of persimmon tannin on Chinese cobra PLA2.

Persimmon tannin (PT) has been shown to inhibit snake venom activities and toxicities both in vitro and in vivo. To clarify the detoxifying mechanism of PT on snake venom, the interaction of characteristic structural elements of PT (EGCG, ECG, EGCG dimer and ECG dimer) and Chinese cobra phospholipase A2 (PLA2) was studied. The results revealed that except non-covalent bonds like hydrogen bonds, hydrophobic bonds and iron bonds were formed between PT and PLA2, covalent interaction was also occurred. PT could bind with the key active residues of PLA2, such as lysine, histidine, tryptophan and tyrosine, restraining their activity and disturbing the structure of PLA2, thus showing detoxifying effects on snake venom.