Cytotoxins (CTXs), are the most established cytotoxic component of venom. They are single-chain polypeptides of 59-61 amino acids. CTXs are basic proteins with hydrophobic three–finger loops.
Snake venom enzyme L-amino acid oxidases (LAAOs), is known for its potent cytotoxicity which induce apoptosis but trigger tissue necrosis at high concentration through the liberation of hydrogen peroxide. Another venom enzyme, phospholipase A2 (PLA2), is also known to cause cytotoxicity. These cytotoxins kill cells by non-selectively disrupting cell membranes. Cytotoxins exhibit various physiological effects which are mainly regulated by modifying cell membrane structure and function. Various pharmacological applications have been suggested for cytotoxins such as their ability to destroy various types of cancer cells