The saponins in bathua (above) are less harmful and more effective than those used in existing spermicides

Bathua, an ordinary backyard weed, may soon be much in demand if a team of researchers from the Indian Institute of Chemical Biology (IICB), Calcutta, has its way.

Although eaten as a leaf vegetable in many parts of the country, bathua — a species of Goosefoot or Pigweed — has so far been considered good enough only as a source of poultry feed. Growing in soils rich in nitrogen, especially in and around wastelands, the black seeds of this famine crop — or Chenopodium album — contain high amounts of protein, vitamin A, calcium, phosphorous and potassium.

Researchers at IICB’s steroid and terpenoid chemistry department were doing a routine job of determining the chemical constituents of an aqueous decoction of Chenopodium album seed (CAD) when they observed that the extract did not show any signs of fungal growth when kept aside even for a week. “It then struck us that it must have some anti-microbial activity,” said Nirup B. Mondal, an author of the study.

Chemical analysis of the decoction revealed that bathua seeds contain saponins (glycosides or sugars with a distinctive foaming characteristic). “And since saponins are a major constituent of the available spermicidal contraceptive formulations, we decided to take the help of the institute’s Department of Reproductive Biology Research (DRBR),” said Mondal.

The collaboration made it easier for the researchers to access test animals like adult Sprague-Dawley rats and rabbits to study the effect of the extract. “When clinically administered to the animals, the CAD extract had the potential to act like a spermicide,” said Shrabanti Kumar, the lead researcher.

Normally, rabbits are chosen for experiments such as this. But rats were also experimented upon here. The female rat has a bicornuate uterus (with two horn-like structures) and during copulation semen is deposited not on the vagina but the cervix (the constricted lower end of the uterus). “We used one uterine horn as the control and one for our experiment, with both structures being subjected to identical conditions,” explained Syed N. Kabir, DRBR head. The extract inhibited fertilisation, thereby preventing conception, whereas fertilisation and implantation occurred unhindered in the control horn.

The researchers found that the saponins in the extract destroyed the acrosomal membrane (protective covering) of almost 95 per cent of the sperms. This immobilised the spermatozoa from reaching the ovum, explained Kumar.

The concentration of the extract used was high and the researchers are hoping that a less powerful solution would also do the job effectively.

So does it mean that CAD would soon be selling as a contraceptive for human use? “We have been successful in our experiments and all I can say that it does have the potential of being used as a vaginal contraceptive for humans,” said Mondal.

However, caution is the key. Saponins also have the ability to kill the bacteria that protect the vaginal linings, thereby facilitating microbial infection and rendering the subject susceptible to sexually transmitted diseases. But the IICB scientists think that the saponins found in bathua might be less harmful and more effective than those used in existing spermicides. Not disclosing the name of the constituent that actually makes the extract spermicidal, they added that if the yield of the component is good the proposed contraceptive would be quite cheap.

The development of safe spermicidal preparations is, therefore, the need of the hour, said Kabir. And the bathua extract may have to go through a battery of safety tests and clinical trials before it hits the market.