A male contraceptive?

MRC News

Scientists may be one step closer to finding a chemical male contraceptive. Preliminary results on a compound isolated from indigenous plants look very promising.

Ever since the revolutionary female contraceptive pill in the 1960s, scientists have been working on the same for the male of the species, but to no avail. But preliminary work on a plant extract by scientists at the MRC and the University of the Western Cape (UWC) might prove to be a step in the right direction. 

The plant extract is found in cloves and also in several Cape indigenous plant species. Mr. Mongezi Mdhluli of the MRC's Diabetes Research Group's Primate Unit, studied the effect the compound had on the fertility of rats as part of his M.Sc. degree. "We found some interesting results in rats. When low doses of this extract were administered to males, they were unable to impregnate, and the effect was also entirely reversible - when the dosing was stopped, the males' fertility returned to normal. Based on these results we decided to extend the study to the African Green monkey. This now forms part of my Ph.D. study," he says. 

They chose the African Green monkey because research conducted at the Primate Unit has shown this species to be an excellent model for human reproduction. First tests have produced similar results to the rat studies: when the male monkeys were treated with low doses of the compound, they were unable to make the females pregnant. But the libido of the monkeys was not affected at all and they experienced no side effects. "This is a very important consideration since men tend to get very suspicious of fertility regulation. One has to realise that in females only one oocyte per cycle needs to be prevented from maturing and/or ovulating, whereas in the male all testicular germ cells need to be stopped from functioning or one has to render maturing sperm in the epididymis non-functional in order to induce infertility. So it is important to find something that doesn't cause permanent damage to the male reproduction tract," he says. 

The scientists are still researching the exact mechanism of the effect. According to Mr. Mdhluli, the extract might play a role during the later stage of spermatogenesis (the process during which sperm is formed). "The membrane of the sperm cells appear to be damaged, resulting in loss of enzymes which enable the sperm to penetrate the oocyte" he explains. Beside the contraceptive effect, studies showed that this compound also had beneficial health effects such as hepatoprotection, anti-inflammation, anti-tumor activity, anti-hyperlipidemia and anti-HIV activity. Mr. Mdhluli works under the supervision of Prof. Gerhard van der Horst of UWC's Department of Physiology and Dr Jürgen Seier of the MRC Diabetes Research Group's Primate Unit. - MRC News

January 2002