Inhibición de las actividades proteolítica y fosfolipasa A2 del veneno de Bothrops asper por el extracto etanólico de Neurolaena lobata (L.) Cass.

Neurolaena lobata has been used by traditional healers in Central America to treat snakebite, but its ability to neutralize Bothrops asper envenomations needs to be proved. This study evaluated the inhibitory potential of the ethanolic extract of the leaves of N. lobata against proteolytic, phospholipase A2 (PLA2), and coagulant activities of the venom in vitro. Leaves were collected in Izabal, Guatemala, dried, extracted with ethanol, and concentration-response assays were conducted to detect intrinsic proteolytic, PLA2 (evaluated as indirect hemolysis), and coagulant activities. Assays for anti-proteolytic and anti-PLA2 activities were performed after pre-incubation of several amounts of extract with a fixed concentration of venom. Inhibition assay for the coagulant effect of the venom was not tested because pre-incubation of thrombin with the extract prolonged the clotting time of plasma in a concentration-dependent manner. Proteolytic (EC50 = 15.7 μg/μl) and PLA2 (EC50 = 32.5 μg/μl) activities of the venom resulted completely inhibited by the extract. Phytochemical profiles, determined by micrometric assays and semi microanalysis by thin layer chromatography, showed the presence of flavonoids, coumarins, saponins, tannins, sesquiterpene lactones, and essential oils in the extract. SDS-PAGE was used to assess the action of the extract on the venom proteins. Results showed changes in the electrophoretic profile, probably due to the formation of insoluble complexes with plant specialized metabolites. These findings demonstrated that the extract could be able to inhibit toxic effects triggered by zinc-dependent snake venom metalloproteinases (SVMPs) y PLA2s but might aggravate the alterations induced by the venom in coagulation.