By Pat Anson, Editor
Black widow spiders are well known for their dangerous, painful and sometimes even lethal bites. The venom of a female black widow is 15 times as toxic as a rattlesnake’s.
But that venom also contains an ingredient that could be developed into a new class of potent painkilllers.
Researchers in Australia have identified seven compounds in the venom of spiders that block the body's ability to send signals to the brain through what is called the pain pathway – also known as Nav 1.7 channels.
"A compound that blocks Nav 1.7 channels is of particular interest for us. Previous research shows indifference to pain among people who lack Nav 1.7 channels due to a naturally-occurring genetic mutation - so blocking these channels has the potential of turning off pain in people with normal pain pathways," said study leader Glenn King, PhD, of The University of Queensland's Institute for Molecular Bioscience.
King and his colleagues built a system that can rapidly analyze the protein molecules in spider venoms. They studied the venom of over 200 spider species and found that 40% of the venoms contained at least one compound that blocked human Nav 1.7 channels. Of the seven promising compounds identified so far, one is particularly potent and has a chemical structure that suggests it has a high level of chemical, thermal, and biological stability, which would be essential for administering in a new medicine.
"Untapping this natural source of new medicines brings a distinct hope of accelerating the development of a new class of painkillers that can help people who suffer from chronic pain that cannot be treated with current treatment options," said researcher Julie Kaae Klint, PhD.
Researchers have only scratched the surface. There are over 45,000 species of spiders, many of which kill their prey with venoms that contain hundreds - or even thousands - of protein molecules that block nerve activity.
"A conservative estimate indicates that there are nine million spider-venom peptides, and only 0.01% of this vast pharmacological landscape has been explored so far," says Klint.
The study is published in the British Journal of Pharmacology.
Researchers are also studying the potential of venom in cone snails for its potential for blocking pain signals in humans. German scientists at the Pharmaceutical Institute of the University of Bonn say one advantage of the peptides found in snail venom is that they decompose quickly and are unlikely to cause dependency.
A pharmaceutical drug derived from cone snail neurotoxins has already been developed and marketed under the brand name Prialt. The drug is injected in spinal cord fluid to treat severe pain caused by failed back surgery, injury, AIDS, and cancer.