Poison for spermatozoa

Poison for arrows of African hunters turned into a male contraceptive

Sergey Vasiliev, Naked Science

Pharmacological contraceptives have been known for a long time, and several completely safe drugs are allowed, tested and massively used by women. It turned out to be much more difficult to create an effective "male" contraceptive, and no such remedy has yet managed to reach pharmacy shelves. An extremely dangerous and ancient toxin gives new hope for this – American scientists write about this in an article published in the Journal of Medicinal Chemistry.

Back in the III century BC, Theophrastus wrote about the custom of the "Ethiopians", as any people of Africa could then be called, to dip arrows into a poisonous decoction obtained on the basis of shoots and leaves of tropical plants Acokanthera (Acokanthera) and lianas Strophanthus. At the end of the XIX century, the active substance was isolated from them, and in the XX century it was studied: the uabain toxin suppresses the work of ion channels, which in the body of a large vertebrate ends with seizures, respiratory and circulatory disorders, up to a heart attack. The semi-annual dose of ouabain is 5 mg per kilogram of body weight.

Thus, the drug can be attributed to cardiac glycosides, herbal preparations, which in microscopic doses can reduce the manifestations of heart failure and arrhythmia. On the other hand, its safety has not been confirmed, so officially the drug based on ouabain is not used, it is also not approved by the authoritative American regulator FDA.

At the same time, a few years ago, Chinese doctors showed that ouabain can cause asthenozoospermia – reduce sperm motility, blocking their ability to fertilize. Then, given the dangerous effect of the drug on the heart, scientists did not expect to use it as a means of "male" non-hormonal contraception. But, judging by the results of new experiments by researchers from the USA and Canada, this possibility still remains.

The authors used male laboratory rats, as well as a number of potentially interesting artificial analogues of ouabain – only slightly modified toxin molecules. Their goal was to search for a substance that would selectively act only on a special type of ion pumps that work only in the beating flagella of sperm.

And indeed, among dozens of drugs tested by scientists, one (with the replacement of the lactone group at the C17 atom with benzotriazole) demonstrated excellent selectivity. He completely suppressed sperm motility and made the males sterile, while not having a noticeable effect on their cardiovascular system. And this gives quite a weighty, although still very distant, hope that contraceptives for men will someday be as accessible as women's ones.

Portal "Eternal youth" http://vechnayamolodost.ru