Sperm are exceptionally good swimmers, and when they near the egg, they pull out all the stops, leaving nothing on the table. But new research shows that traditional herbal remedies may take the wind right out of their sails. For researchers, the chemicals responsible point the way to a promising contraceptive.
Polina Lishko and her colleagues from the University of California Berkeley tested the contraceptive action of two steroid-like chemicals from plants used in traditional medicines: pristimerin and lupeol. Pristimerin comes from a vine, known as “thunder god vine”, and it appears in traditional Chinese medicines to treat arthritis. The other, lupeol, can be found in all sorts of fruits and vegetables and has been used in traditional medicines around to world as anti-cancer treatments.
Neither are deadly to sperm, but can still slow the gametes to a crawl. Lishko and her colleagues started their research by susssing out exactly how sperms lash their way toward an egg. They found that progesterone—a hormone secreted by cells surrounding eggs—opens the calcium ion channel and gives them the extra boost as they near the finish line. Other compounds, like testosterone, estrogen, and the stress-related hydrocortisone, can block the channel. Here’s Beth Mole reporting for ArsTechnica:
In lab tests, the two [chemicals] didn’t do much to sperm on their own—the sperm stay alive and motile. But, in the presence of progesterone, [they] prevented the ion channel from activating and powering the potent tail flicks. The sperm were left able to gently sway their tails and idly float around. But, they could not build up the speed and power needed to drill down into an egg’s outer layers and fuse to the membrane—which is required for fertilization.
Since these chemicals are already used in traditional remedies, the researchers are hopeful they’ll easily pass safety tests. And unlike other forms of birth control, which rely on hormones, they avoid unpleasant side-effects such as changes in mood, weight, and libido. But for now, these chemicals are still in the early testing phase, which means it’ll be years before they appear in marketable products.