Chimpanzees appear to consume plants with medicinal properties to treat their illnesses and injuries, according to a new study by researchers from the University of Oxford. The findings may fast-track the discovery of therapeutics against antibiotic-resistant bacteria and chronic inflammatory diseases.

The findings are published in PLOS ONE in an article titled, “Pharmacological and behavioral investigation of putative self-medicative plants in Budongo chimpanzee diets.”

“Wild chimpanzees consume a variety of plants to meet their dietary needs and maintain well-being,” the researchers wrote. “While some plants have obvious value, others are nutritionally poor and/or contain bioactive toxins which make ingestion costly. In some cases, these nutrient-poor resources are speculated to be medicinal, and thought to help individuals combat illness. In this study, we observed two habituated chimpanzee communities living in the Budongo Forest, Uganda, and collected 17 botanical samples associated with putative self-medication behaviors (e.g., bark feeding, dead wood eating, and pith-stripping) or events (e.g., when consumer had elevated parasite load, abnormal urinalysis, or injury). In total, we selected plant parts from 13 species (nine trees and four herbaceous plants). Three extracts of different polarities were produced from each sample using n-hexane, ethyl acetate, and methanol/water (9/1, v/v) and introduced to antibacterial and anti-inflammatory in vitro models.”

The researchers combined behavioral observations of wild chimpanzees (Pan troglodytes) with pharmacological testing of the potentially medicinal plants they eat. They monitored the behavior and health of 51 chimpanzees from two habituated communities in the Budongo Central Forest Reserve in Uganda.

The researchers then collected plant extracts from 13 species of trees and herbs in the reserve that they suspected the chimpanzees might be using to self-medicate, and tested them for their anti-inflammatory and antibiotic properties.

The researchers found that 88% of the plant extracts inhibited bacterial growth, while 33% had anti-inflammatory properties.

The researchers observed dead wood from a tree in the Dogbane family (Alstonia boonei) showed the strongest antibacterial activity and also had anti-inflammatory properties, suggesting that it could be used to treat wounds. Bark and resin from the East African mahogany tree (Khaya anthotheca) and leaves from a fern (Christella parasitica) exhibited potent anti-inflammatory effects. The researchers observed a male Chimpanzee with an injured hand seek out and eat leaves of the fern, which may have helped to reduce pain and swelling. They also recorded an individual with a parasitic infection consuming the bark of the cat-thorn tree (Scutia myrtina).

The results suggest that chimpanzees seek out specific plants for their medicinal effects. The study is one of the first to provide both behavioral and pharmacological evidence of the medicinal benefits to wild chimpanzees of feeding on bark and dead wood. The medicinal plants growing in Budongo Central Forest Reserve could also be helpful for the development of new drugs to address the challenges of antibiotic-resistant bacteria and chronic inflammatory diseases, the authors said.

The authors added: “In this paper, we demonstrate how watching and learning from our primate cousins may fast-track the discovery of novel medicines, while also emphasizing the importance of protecting our forest pharmacies.”

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