Fancy eating a kroma fruit? How about a prickly badi? Or zoobo leaves?
If you are feeling unwell, perhaps you should. These West African plants are part of a ‘jungle pharmacy’ sought out by wild chimpanzees to treat ailments ranging from worm infestations to bacterial infections. And because humans share 98% of their DNA with chimps, and are susceptible to some of the same diseases, they might work on people too.
At least that is the theory behind a research project in Côte d’Ivoire that is screening such plants for possible human treatments. So far it has identified compounds that able to kill bacterial and yeast infections in a petri dish, and even some that seem to inhibit cancer development. Eventually, such discoveries could lead to new antibiotics, antifungals or cancer treatments.
But drug discovery is a long road, and these compounds have only passed the first hurdle says Constant Ahoua, the Ivorian botanist in charge of the project. Ahoua, a postdoctoral researcher at the Afrique One-ASPIRE programme based in Abidjan, has been studying chimp diets for a decade. For his PhD he screened 27 plant species eaten by wild chimps, specifically targeting those not already known to be used in traditional human medicine. Of the extracts he made from the plants, 18% were active against bacteria and 5% against yeasts.
Next up, Ahoua will publish a paper on the anti-cancer compounds he discovered in his research. “We found seven compounds that inhibit cancer-triggering enzymes, and two of them are completely new,” he says.
Chimps are not the only animals that self-medicate. Pregnant elephants in Kenya seek out certain tree leaves to induce labour. Wild boars in India seek out and eat a root used by humans too to get rid of parasitic worms. And cats and dogs eat grass to induce vomiting. Whether these are innate or learned behaviors is often still unknown.
Learning about the medicinal uses of plants from studying which animals eat them, and when, is not a novel idea says Michael Huffman, a professor at the Primate Research Institute in Kyoto, Japan. However, the medicinal plants that have been discovered from the study of animal diets are mostly also recorded in traditional human medicine.
“For this reason I think the work in progress in Côte d’Ivoire is very valuable,” Huffman says. “We can never have enough of these kinds of studies since the plant flora across Africa is diverse and animals in one part of Africa will definitely be exploiting different species than the same or related species in different parts of the continent.”
Kelly Chibale, head of the H3D drug discovery unit at the University of Cape Town in South Africa, says it’s difficult to say at this point whether the findings would be suitable for human drug development. That would depend on the whether the active compounds discovered are new, and whether or not they are suitable for pharmaceutical processing, he says.
The next step for would be to see whether the compounds can fight disease in a model animal like a lab mouse. If they do, then follows a battery of trials carefully designed to judge their safety and efficacy in humans—a long and costly journey. In other words, don’t expect simian drugs to appear in your pharmacy anytime soon.