Such pharmacologically active biomolecules may induce angiogenesis, inhibit protein synthesis by the cell, induce apoptosis, display antiviral activity, among others. Examples are streptokinase, a plasminogen activator produced by Streptococcus spp. ( Tillet et al., 1948); betulinic acid,

produced by betula, which induces the death of melanoma cells and whose derivatives inhibit HIV ( Pisha et al., 1995 and Evers et al., 1996); immunotoxins, also known as magic bullets, which are chimeric proteins comprehending an antibody with specificity for the target cell coupled to a toxin ( Barbieri JQ1 et al., 1993 and Keppler-Hafkemeyer et al., 1998). Venom-producing animals are usually known solely for the negative effects they cause after accidental contact with humans; they carry a variety of toxins with different physiological activities that cause mild symptoms, such as allergic reactions and dermatitis, or very severe symptoms, like coagulation disorders including hemorrhage and disseminated intravascular coagulation, besides as well as necrosis and, respiratory arrest, among other complications. Even though the effects of the envenomations might lead to a negative reputation,

this website these animals are also seen, by many scientists, as a rich source of pharmacologically active principles, and many of their toxins have been the subject of research projects aiming the development of new molecules for the diagnosis, treatment and cure of some types of diseases (Veiga et al., 2009). Examples of active principles produced by animals that have been employed in laboratory kits or in the treatment of cardiovascular problems include (Kini, 2006 and Marsh and Williams, 2005): textarin and ecarin, prothrombin activators from snake venom that are used in the diagnosis of systemic lupus erythematosus; hirudin, a thrombin inhibitor from the saliva of the leech Hirudo medicinalis; batroxobin, from Etomidate the venom of

Bothrops atrox and B. moojeni, which is the active principle of Defibrase®, used to treat thrombosis, and Reptilase™, used to measure fibrinogen levels in plasma; captopril, the best known and most used anti-hypertensive, derivate from the venom of B. jararaca; ancrod, the fibrinolytic principle from the venom of Agkistrodon rhodostoma present in Viprinex™, used for cerebral and peripheral limb ischemia. Therefore, animal toxins have widened the field of the drug development industry. Anti-cancer therapy is one of the main areas for the use of proteins and peptides originating from animals. Some of these proteins or peptides, when isolated, may bind specifically to cancer cell membranes, affecting the migration and proliferation of these cells.