Inhibitors of Reptile Venom Toxins

Among the diverse toxins found in snake venoms, proteins belonging to the families of metalloproteinases (SVMPs) and phospholipases A₂ (PLA₂s) are often particularly abundant and are responsible for a wide spectrum of pharmacological effects resulting in the clinical manifestations of snake envenoming. To maintain homeostasis in response to such potent exogenous agents, the development of natural mechanisms of resistance to venoms and toxins is a common evolutionary response. Several distinct types of molecules that act as endogenous inhibitors of SVMPs have been classified into five groups or families: 1) the immunoglobulin superfamily; 2) the cystatin superfamily; 3) the ficolin/opsonin P35 family; 4) a family of uncharacterized proteins and 5) several endogenous peptides. Similarly, endogenous PLA₂ inhibitors (PLIs) have been purified from the plasma of snakes and are classified into three types: PLIs-α, PLIs-β and PLIs-γ. Throughout this chapter, aspects of SVMPs and PLA₂s inhibitors that have been reported in the literature are discussed. The characterization of these natural inhibitors, as well as the elucidation of the structural and functional mechanisms involved in the inhibition of toxins, can contribute considerably to the identification of molecules capable of becoming valuable tools with biotechnological potential that are able to assist in the treatment of snakebite.