Chimps’ self-medication with plants could aid drug discovery

A landmark study has revealed that wild chimpanzees use medicinal plants to treat themselves when ill, a finding that could assist in the search for new drugs.

Researchers led by Dr Elodie Freymann from the University of Oxford spent months observing the behaviour of a 51-strong troop of chimps in the Budongo Central Forest Reserve in Uganda, discovering that individuals with obvious signs of illness seem to seek out plants that are nutritionally poor, but could have medicinal properties.

The team acknowledges that it is hard to determine whether chimps intentionally seek out plants with properties that help their specific ailments or passively consume plants that happen to be medicinal.

However, their research went a step further by taking samples of the plants the sick chimps were eating and analysing them for pharmacological constituents, as well as collecting samples of faeces and urine to test for illness. The samples were tested in the lab of Dr Fabien Schultz at the Neubrandenburg University of Applied Sciences in Germany.

They observed that some of the plants used by primates showing signs of injury or illness were not part of their normal diet.

For example, one male with an injured hand sought out a particular species of fern that was not consumed by others in the troop.

They came up with a list of 13 different species of tree and herb that were tested for anti-inflammatory and antibiotic properties. All told, 88% of the plant extracts inhibited bacterial growth, while 33% had anti-inflammatory properties and may promote wound healing.

In the case of the injured male, the fern species (Christella parasitica) was subsequently shown to have potent anti-inflammatory properties, while dead wood from a tree in the Dogbane family (Alstonia boonei) showed the strongest antibacterial activity. They also recorded an individual with a parasitic infection consuming the bark of the cat-thorn tree (Scutia myrtina).

While scientists have tried to hunt for new drug leads in fauna and flora samples for decades, that is generally a very hit-and-miss affair unless guided by local human knowledge.

This targeted ‘zoopharmacognosy’ approach in non-human primates could unlock another line of research and – given the findings involving antibacterial plants – could help in the search for novel antimicrobials at a time when resistance to current drugs is rising to dangerously high levels.

“In this paper, we demonstrate how watching and learning from our primate cousins may fast-track the discovery of novel medicines, while also emphasising the importance of protecting our forest pharmacies,” they write in a paper on the study published in the open-access journal PLOS One.