Inhibition of edema-forming and hemorrhagic activities of Bothrops asper snake venom by Phenax angustifolius and Phenax rugosus (Urticaceae) extracts

The aim of this work was to investigate the capacity of crude extracts of roots, stems and leaves from Phenax angustifolius (H.B.K.) Weddell and Phenax rugosus (Poir.) Weddell in DC. (Urticaceae) to inhibit the edema-forming and hemorrhagic activities induced by Bothrops asper snake venom. Edema-forming activity was studied plethysmographically in the rat hind paw model. Groups of rats were preinjected intraperitoneally (ip) with various doses each extract and, one hour later, venom was injected subcutaneously (sc) in the right hind paw. Edema was assessed at various time intervals. Results showed that the edematogenic activity was inhibited in those animals that received an injection of either root or stem extracts from P. angustifolius. In contrast, extracts from leaves of both plants induced a pro-inflammatory effect, increasing edema in some of the doses tested. On the other hand, the anti-hemorrhagic effect was evaluated by the intradermal (id) mouse skin test. Venom and the extracts were incubated and then injected into groups of mice. Our findings evidenced that root and stem extracts of P. angustifolius were able to inhibit hemorrhagic activity. In contrast, extracts from leaves of both plants potentiated the hemorrhagic activity of the venom. Furthermore, a partial inhibition of proteolytic activity of venom on biotynilated casein was achieved with some of the extracts.