Proteomic characteristics of six snake venoms from the Viperidae and Elapidae families in China and their relation to local tissue necrosis

Patients envenomed by snakes from the Viperidae and Elapidae families in China often have varying degrees of local tissue necrosis. Due to the relative clinical characteristics of local tissue necrosis and ulceration following envenoming, this study has analyzed the proteome of six snake venoms from the Viperidae and Elapidae family, and the toxin profiles of each snake were compared and correlated with the clinical manifestations that follow cytotoxic envenoming. Deinagkistrodon acutus and Naja atra envenomation induce severe ulceration, which is absent in Bungarus multicinctus envenomation and mild in the other three vipers. It is interesting to note that the proportion of c-type lectins (CTL) (20.63%) in Deinagkistrodon acutus venom was relatively high, which differs from the venom of other vipers. In addition, three-fingered toxin (3FTx) (2.15%) is present in the venom of Deinagkistrodon acutus, but has not been detected in the remaining three vipers. Snake venom metalloprotease (SVMP) (34.4%-44.7%), phospholipase A2 (PLA2) (9.81%-40.83%), and snake venom serine protease (SVSP) (9.44%-16.2%) represent the most abundant families of toxin in Viperidae venom. The Elapidae venom proteome was mainly composed of neurotoxins and cytotoxins, including 3FTx (39.28%-60.08%) and PLA2 (8.24%-58.95%) toxins, however, the proportion of CRISPS (26.36%) in Naja atra venom was relatively higher compared to Bungarus multicinctus venom. Significant differences in SVMP, SVSP, and 3FTx expression levels exist between the Viperidae and the Elapidae family. The main toxins responsible for the development of tissue necrosis and ulcerations following Viperidae envenoming are hematotoxins (SVSMP, SVSP) and myotoxins (PLA2). Deinagkistrodon acutus venom contains high levels of CTL and traces of 3FTx, leading to more severe local necrosis. However, Naja atra venom can also cause severe local necrosis through the effects of myotoxin (3FTx, CRISP, PLA2). Bungarus multicinctus venom does not contain myotoxins, resulting in pure systemic neurological manifestations no obvious necrosis of local tissue in patients.

Hesperetin as an inhibitor of the snake venom serine protease from Bothrops jararaca

The majority (90%) of the snakebite envenomation in Brazil accounts for Bothrops from the Viperidae family. Some snake venom serine proteases provoke blood coagulation in ophidian accident victims because of their fibrinolytic activity, one of those proteases from Bothrops jararaca (B. jararaca) has been chosen for this study. Our objectives were to isolate and characterize the target serine protease; isolate, purify, and characterize the orange bagasse flavone (hesperetin, Hst), and investigate the interactions between the targets, enzyme, and hesperetin. The purified serine protease was named BjSP24 because of its molecular mass and proteolytic activity. BjSP24 was folded and characterized using circular dichroism and showed low alpha-helix contents (7.7%). BjSP24 exhibited sequence similarity to other known snake venom serine proteases as measured in the enzyme tryptic peptides' LC-MS/MS run. Hesperetin was obtained within the expected yield and with the predominance of 2S isomer (82%). It acted as a mixed inhibitor for the serine protease (SVSP) from Bothrops jararaca snake venom observed in three different in vitro experiments, fluorescence, kinetics, and SSTD-NMR. It is still to determine if hesperetin might aid-in reverting the on site blood clotting problems just after snakebite accidents.