RESUMO
The anti-venom activity of Andrographis paniculata (Burm.f.) Nees roots (APR) dichloromethane crude extractsand a promising APR constituent, skullcapflavone I (SKI) was investigated by monitoring the inhibition of secretoryphospholipase A2 (sPLA2) of Naja philippinensis Taylor venom (NPV) crystallized samples. Gas chromatographymass spectrometry was used for the characterization of extracts, while molecular docking was utilized to understandanti-venom properties. Chromatographic analyses primarily revealed the presence of methoxylated flavones. NPV wasfound to have sPLA2 activity (0.0796 ± 0.0018 μmol/minutes/ml) that has been attributed to the poisonous effects.SKI (IC50: 51.1 ± 3.5 μg/ml), isolated from APR showed strong inhibitory effect on phospholipase activity comparedwith dichloromethane extracts of APR (IC50: 192.7 ± 10.9 μg/ml) indicating that SKI was the cause of the bioactivityin APR. Molecular docking simulations showed corresponding results with highly negative binding energies (−6.59 to−8.72 kcal/mol) predicted for the binding of SKI to PLA2 proteins. An important trend found was the presence of freebound Ca2+ lowered binding energies signifying that Ca2+ a has role in the binding of the SKI to PLA2 proteins. Theanti-venom property of APR and the pure compound SKI, upon further studies, could be the first line of defense in themedical protocol of snake venom neutralization.