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Abstract:The prominent myotoxic effects induced by Bothrops jararacussu crude venom are due, in part, to its polycationic myotoxins, BthTX-I and BthTX-II. Both myotoxins have a phospholipase A2 structure: BthTX-II is an active enzyme Asp-49 PLA2, while BthTX-I is a Lys-49 PLA2 devoid of enzymatic activity. In this study, the effect of low-level laser therapy (LLLT), 685 nm laser at a dose of 4.2 J/cm2 on edema formation, leukocyte influx and myonecrosis caused by BthTX-I and BthTX-II, isolated from Bothrops jararacussu snake venom, was analyzed. BthTX-I and BthTX-II caused a significant edema formation, a prominent leukocyte infiltrate composed predominantly by neutrophils and myonecrosis in envenomed gastrocnemius muscle. LLLT significantly reduced the edema formation, neutrophil accumulation and myonecrosis induced by both myotoxins 24 hours after the injection. LLLT reduced the myonecrosis caused by BthTX-I and BthTX-II, respectively, by 60 and 43%; the edema formation, by 41 and 60.7%; and the leukocyte influx, by 57.5 and 51.6%. In conclusion, LLLT significantly reduced the effect of these snake toxins on the inflammatory response and myonecrosis. These results suggest that LLLT should be considered a potential therapeutic approach for treatment of local effects of Bothrops species venom.

Most of the snakebites recorded in Brazil are caused by the Bothrops genus. Given that the local tissue damage caused by this genus cannot be treated by antivenom therapy, numerous studies are focusing on supplementary alternatives, such as the use of medicinal plants. Serjania erecta has already demonstrated anti-inflammatory, antiseptic and healing properties. In the current study, the aerial parts of S. erecta were extracted with methanol, then submitted to chromatographic fractionation on a Sephadex LH20 column and eluted with methanol, which resulted in four main fractions. The crude extract and fractions neutralized the toxic activities of Bothrops jararacussu snake venom and isolated myotoxins (BthTX-I and II). Results showed that phospholipase A2, fibrinogenolytic, myotoxic and hemorrhagic activities were inhibited by the extract. Moreover, the myotoxic and edematous activities induced by BthTX-I, and phospholipase A2 activity induced by BthTX-II, were inhibited by the extract of S. erecta and its fraction. The clotting time on bovine plasma was significantly prolonged by the inhibitory action of fractions SF3 and SF4. This extract is a promising source of natural inhibitors, such as flavonoids and tannins, which act by forming complexes with metal ions and proteins, inhibiting the action of serineproteases, metalloproteases and phospholipases A2

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