Inhibition of proteolytic activity of Bothrops alternatus venom by two small molecules and docking analysis against a snake venom metalloproteinase.

The only effective treatment against snakebites is the administration of antivenom. Snake venom metalloproteinases (SVMPs) play a key role in the pathogenesis of envenomation. In this work, the ability of two molecules to inhibit the proteolytic activity of Bothrops alternatus venom and its PIII SVMP (baltergin) was studied: a dye (alizarin red S: Az) and a vitamin (l-ascorbic acid: AA). Neutralization of hemorrhage and docking analysis were also carried out. The inhibition of the proteolytic activity, showed the IC50 for Az (3.6 mM) was 52 times lower than for AA (188.2 mM). Az was not only able to inhibit casein degradation but also a milk protein compatible with beta-lactoglobulin, meanwhile AA was only capable of inhibit the degradation of casein. Both molecules were able to completely inhibit the action of baltergin on casein degradation. It was also observed that the antioxidant activity of Az increased, while the activity of AA decreased after exposition to visible radiation. As a result, Az induced an increase in its proteolytic inhibitory potential, although no significant changes were observed with AA. A partial neutralization of hemorrhage was observed, representing 46 % of inhibition, only for Az at a venom:molecule ratio (m:m) of 1:4. It was demonstrated that Az interacts with PIII SVMPs through more bonds than with AA, which makes it fit better in the vicinity of the catalytic site. Natural (or synthetic) dyes open up a new range of possibilities for exploring alternatives for the complementary treatment of snakebites.