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A post-synaptic neurotoxic phospholipase A(2) (PLA(2)) has been purified from Indian cobra Naja naja venom. It was associated with a peptide in the venom. The association was disrupted using 8 M urea. It is denoted to be a basic protein by its behavior on both ion exchange chromatography and electrophoresis. It is toxic to mice, LD(50) 1.9 mg/kg body weight (ip). It is proved to be post-synaptic PLA(2) by chymographic experiment using frog nerve-muscle preparation. A glycoprotein, (WSG) was isolated from a folk medicinal plant Withania somnifera. The WSG inhibited the phospholipase A(2) activity of NN-XIa-PLA(2,) isolated from the cobra venom, completely at a mole-to-mole ratio of 1:2 (NN-XIa-PLA(2): WSG) but failed to neutralize the toxicity of the molecule. However, it reduced the toxicity as well as prolonged the death time of the experimental mice approximately 10 times when compared to venom alone. The WSG also inhibited several other PLA(2) isoforms from the venom to varying extent. The interaction of the WSG with the PLA(2) is confirmed by fluorescence quenching and gel-permeation chromatography. Chemical modification of the active histidine residue of PLA(2) using p-brophenacyl bromide resulted in the loss of both catalytic activity as well as neurotoxicity of the molecule. These findings suggest that the venom PLA(2) has multiple sites on it; perhaps some of them are overlapping. Application of the plant extract on snakebite wound confirms the medicinal value associated with the plant.

Venom hyaluronidases help in rapid spreading of the toxins by destroying the integrity of the extra-cellular matrix of the tissues in the victims. A hyaluronidase inhibitor (WSG) is purified from a folk medicinal plant, Withania somnifera. The glycoprotein inhibited the hyaluronidase activity of cobra (Naja naja) and viper (Daboia russelii) venoms, which was demonstrated by zymogram assay and staining of the skin tissues for differential activity. WSG completely inhibited the activity of the enzyme at a concentration of 1:1 w/w of venom to WSG. Thus we are able to demonstrate that the glycoprotein inhibits hyaluronidase activity of the venoms. External application of the plant extract as an antidote in rural parts of India to snakebite victims appears to have a scientific basis.