The anti-snake activity of Nectandra angustifolia flavonoids on phospholipase A2: in vitro and in silico evaluation

Ethnopharmacological relevance: Lauraceae family includes Nectandra angustifolia a species widely used in the folk medicine of South America against various maladies. It is commonly used to treat different types of processes like inflammation, pain, and snakebites. Snakes of the Bothrops genus are responsible for about 97% of the ophidic accidents in northeastern Argentina. Aim of the study: To evaluate the anti-snake activity of the phytochemicals present in N. angustifolia extracts, identify the compounds, and evaluate their inhibitory effect on phospholipase A2 (PLA2) with in vitro and in silico assays. Methods: Seasonal variations in the alexiteric potential of aqueous, ethanolic and hexanic extracts were evaluated by inhibition of coagulant, haemolytic, and cytotoxic effects of B. diporus venom. The chemical identity of an enriched fraction obtained by bio-guided fractioning was established by UPLC-MS/MS analysis. Molecular docking studies were carried out to investigate the binding mechanisms of the identified compounds to PLA2 enzyme from snake venom. Results: All the extracts inhibited venom coagulant activity. However, spring ethanolic extract achieved 100% inhibition of haemolytic activity. Bio-guide fractioning led to an enriched fraction (F4) with the highest haemolytic inhibition. Five flavonoids were identified in this fraction; molecular docking and Molecular Dynamics (MD) simulations indicated the binding mechanisms of the identified compounds. The carbohydrates present in some of the compounds had a critical effect on the interaction with PLA2. Conclusion: This study shows, for the first time, which compounds are responsible for the anti-snake activity in Nectandra angustifolia based on in vitro and in silico assays. The results obtained in this work support the traditional use of this species as anti-snake in folk medicine.