Snake venom is a complex cocktail of enzymes, peptides, and proteins that has evolved to quickly immobilize and kill prey. However, new research is revealing that some components of snake venom have medicinal properties and can potentially be used to treat a variety of diseases in humans.
How does snake venom work?
Snake venom works by targeting vital systems in the body. Different snake species have different venoms adapted to their preferred prey. Here are some of the main ways snake venom can affect the body:
- Neurotoxins – Target the nervous system, blocking communication between nerves and muscles to cause paralysis.
- Hemotoxins – Damage red blood cells and prevent blood from clotting.
- Cytotoxins – Destroy tissues and cause necrosis at the bite site.
- Cardiotoxins – Disrupt heart muscle function.
Many snake venoms contain a mix of these toxic components to immobilize and start digesting prey quickly. However, researchers have noticed that low doses of venom can have different effects than high doses used for killing prey. This has led to interest in using snake venom components medicinally.
1. Pain relief
Certain peptides in snake venom have been found to have pain-relieving effects when administered in small doses. One component that shows promise is crotalphine from the venom of South American rattlesnakes. Crotalphine is a neurotoxin that blocks pain signals by targeting NMDA receptors involved in pain transmission in the spinal cord.
In rodent studies, crotalphine was found to provide potent short-term pain relief without sedative side effects. The effects were comparable to morphine but did not lead to dependency after repeated doses. Researchers believe crotalphine could form the basis of a powerful analgesic medication with a lower risk of addiction.
Other snake venom painkillers
Several other snake venom components target pain pathways:
- Conotoxins from cone snail venom block pain signals and are being investigated for severe nerve pain treatment.
- Waglerins from the Temple Viper target ion channels involved in pain response.
- Pseudonajatoxin from the Egyptian Cobra blocks receptors that send pain signals.
Developing new snake venom drugs could provide alternatives to opioids for treating chronic pain.
2. Antibiotics
The antimicrobial properties of snake venom also hold promise for new antibiotics. Venom is loaded with small antibacterial polypeptides that snakes use to quickly kill prey. Many bacterial strains are now resistant to traditional antibiotics, raising the need for new approaches.
A key venom peptide with antibiotic potential is cathelicidin-BF from the Banded Krait. In lab tests, cathelicidin-BF showed powerful bactericidal effects against drug-resistant strains, including methicillin-resistant Staphylococcus aureus (MRSA).
Cathelicidin-BF appears to work by rupturing bacterial cell membranes, an effect that makes it difficult for resistance to develop. The peptide is now being researched as a novel weapon against superbugs.
Other venom antibiotics
Additional snake venoms contain peptides with antibiotic action:
- Nawaprin from King Cobra venom kills MRSA and treats skin infections in mice.
- Vipericidins from different vipers have antibacterial effects against intestinal and wound infections.
- Crotalicidin from a South American Rattlesnake is effective against systemic infections in mice.
Harnessing this snake venom library could augment our antibiotic arsenal and combat the growing threat of drug resistance.
3. Anti-cancer effects
Snake venom cytotoxins like cardiotoxins and myotoxins that destroy cells and tissue can also selectively kill cancer cells. Cardiotoxin III from the King Cobra specifically targets cancer cell membranes based on their unique molecular composition.
In mice implanted with human breast cancer cells, injections of cardiotoxin III significantly reduced tumor growth and metastasis compared to controls. Meanwhile, non-cancerous cells were spared at the doses tested.
Other cell-destroying snake venom components also exhibit anti-cancer potential. Crotamine from the South American rattlesnake inhibits proliferation and migration in melanoma and breast cancer cells.
The ability to selectively target cancer cells makes snake venoms a promising source of novel chemotherapy agents.
Mechanisms of anti-cancer venom peptides
Here are some of the ways snake venom peptides combat cancer:
- Blocking tumor growth signals
- Cutting off blood supply to tumors
- Preventing metastasis
- Damaging cancer cell DNA
4. Anti-viral effects
In addition to bacteria, snake venoms contain peptides that can neutralize viruses. Several venom peptides have shown activity against HIV, preventing the virus from fusing with and entering host cells.
For example, a peptide from King Cobra venom called V13K inhibits HIV infection at very low concentrations by binding to the gp120 viral coat protein. This prevents HIV from attaching to host CD4 receptors, stopping the virus in its tracks.
Besides HIV, components of other snake venoms can inhibit viruses like measles, SARS-CoV, and dengue according to preliminary research. The antiviral potentials of snake venoms are still being explored.
Mechanisms of antiviral snake venom peptides
Snake venom peptides use various strategies against viruses:
- Blocking viral entry into cells
- Preventing viral replication
- Stimulating the immune response against viruses
- Breaking down the protective viral envelope
5. Reducing inflammation
Although snake venom is designed to cause inflammation, some specific anti-inflammatory venom peptides have been discovered. A peptide called barbourin from the Pygmy Rattlesnake inhibits platelet aggregation. This prevents excessive blood clotting that worsens conditions like arthritis and stroke.
Meanwhile, contortrostatin from the Southern Copperhead is being researched for treating breast cancer and arthritis. It appears to reduce inflammatory immune signaling that contributes to disease progression.
Targeting inflammatory pathways makes anti-inflammatory snake venom peptides useful for a wide array of chronic inflammatory conditions.
Other anti-inflammatory snake venom peptides
- Alboluxin from King Cobra venom suppresses joint inflammation in rodent arthritis models.
- Cathelicidin-BF from Banded Krait venom reduces inflammation and edema.
- Vipegitide from the Saw-scaled Viper inhibits inflammatory cytokines.
Challenges with using snake venom medically
While snake venom shows promise for generating new drugs, there are challenges to overcome:
- Ensuring safety – Venom components must be rigorously tested for toxicity and side effects before therapeutic use in humans.
- Avoiding immune reactions – People can develop antibodies against snake venom peptides, potentially neutralizing effects.
- High production costs – It takes a lot of venomous snakes to produce sufficient compounds for research and clinical testing.
- Preserving wild populations – Sustainable harvesting practices are needed to avoid endangering wild snakes.
With careful research and testing, snake venom could one day provide safer, more effective treatments for many diseases.
Conclusion
The toxic properties of snake venom make it a double-edged sword – it can kill but also contains compounds to cure. Snake venoms are a pharmacopeia of peptides with antimicrobial, analgesic, anti-inflammatory, and anticancer effects valuable for drug development. While challenges exist in harnessing snake venom safely, components hold promise as the next generation of potent medicines if these hurdles can be overcome through ongoing research.