Isolation of a snake venom phospholipase A2 (PLA2) inhibitor (AIPLAI) from leaves of Azadirachta indica (Neem): Mechanism of PLA2 inhibition by AIPLAI in vitro condition

A compound (AIPLAI (Azadirachta indica PLA2 inhibitor)) purified from the methanolic leaf extract of A. indica (Neem) inhibits the cobra and Russell's viper venoms (RVVs) phospholipase A2 enzymes in a dose-dependent manner. Inhibition of catalytic and tested pharmacological properties of cobra venom (Naja naja and Naja kaouthia) PLA2 enzymes by AIPLAI is significantly higher (P<0.05) compared to the inhibition of PLA2 enzymes of crude RVV (Daboia russelli) when tested under the same condition. Kinetic study reveals that in in vitro condition, AIPLAI inhibits the purified N. kaouthia PLA2 enzymes in a non-competitive manner. The AIPLAI is quite stable at room temperature. The present study shows that AIPLAI holds good promise for the development of novel anti-snake venom drug in future.