Snake and Spider Venom Also Help Save Lives
The creatures we fear are also aiding the development of drugs for diabetes, cancer, neurological disorders and inflammatory diseases.
Earlier this year, scientists from California devised nanoparticles that sop up a variety of common venom toxins in test tube studies, a key stride in coming up with the first ever broad-spectrum snake antivenom. Yet for all the dangers that venomous snakes—and spiders—pose, they also play a role in fighting disease.
Poisonous organisms and the toxic effect of their venom have long been objects of both fear and fascination. The evolution of venom systems is remarkably poorly understood despite their biological uniqueness and medical importance. Venom systems are key evolutionary innovations in a broad phylogenetic range of animal lineages, and are used for defense, competitor deterrence, and predation.
Owing to their worldwide distribution, reptiles are among the most familiar venomous animals, but numerous other organisms on land and sea are equipped with venomous fangs, spines, barbs, or tentacles for the purposes of aggression, defense, or digestion. In addition to the extensively studied, medically-important classes (snakes, scorpions, and spiders), other venomous animals include sea anemones, jellyfish, sea snails, cephalopods, centipedes, several insect orders, echinoderms, fish, lizards, and even some mammals (lorises, platypuses, and shrews).
Targets of venom action include virtually all major physiological pathways and tissue types accessible by the bloodstream. Venoms of snakes contain at least 25 enzymes, inorganic substances, and small amounts of metal. In most species, the most lethal component of the venom is a peptide constituent.
Some of the more important enzymes of reptiles include: proteolytic enzymes, phosphomonoesterase, arginine ester hydrolase, phosphodiesterase, thrombinlike enzyme, acetylcholinesterase, collagenase, RNase/DNase, hyaluronidase, 5’-Nucleotidase, L-Amino acid oxidase, and many more. Such enzymes catalyze the breakdown of tissue proteins and peptides but the pharmaceutical / toxicologic properties of many of these enzymes have not been well characterized.
While venoms can be used as a means to destroy life, they can also be used to save life.
- Antivenin (Antivenom) Immunotherapy: A serum composed of purified antibodies that is commercially produced to neutralize the effects a venom-laced bite or sting.
- Integrilin: A cyclic heptapeptide derived from a protein in the venom of the pygmy rattlesnake. The product was launched by Schering Plough in 1998 and approved for anticoagulation in patients with Acute Coronary Syndrome.
- Exendin-4: A peptide initially derived from the salivary secretions of the Gila monster (see picture below). In 1982, it was observed that the crude venom of the Gila monster (Heloderma suspectum) was a potent pancreatic stimulator of insulin. Purification and sequencing of the active factors mediating this effect led to the discovery of the peptide exendin-4, a 39-amino acid GLP-1 receptor agonist sharing ~53% homology with native GLP-1 and VIP. This peptide possesses glucoregulatory actions similar to GLP-1 and is resistant to degradation activity of DPP-IV because of a different amino acid sequence. The result is longer duration of action in vivo compared to native GLP-1. Byetta (exenatide) is approved for the treatment of type 2 diabetes.
Other areas of research looking at applying venom therapeutically include analgesia, cancer, neurological disorders, and inflammatory diseases.
The nature we occasionally fear continues to provide inspiration and aid to drug developers, who, even with the advent of new technologies, cannot match its complexity and diversity.
A version of this blog first appeared in the American Association of Pharmaceutical Scientists blog.