Gorillas in Gabon May Reveal Medicinal Plants in Moukalaba-Doudou National Park

Gorillas and people have, for generations, sampled the abundant variety of plants growing in the humid rainforest of Moukalaba-Doudou National Park in Gabon, a country in central Africa.

Together, they have revealed plants that provide food and can sometimes offer healing properties. A scientific study has now examined this knowledge, which has long been held by local traditional healers and herbalists.

Gorillas and medicinal plants in Moukalaba-Doudou National Park

"Several studies have shown that plants from the diet of great apes, including western lowland gorilla, are also used as medicinal plants by healers in traditional African medicine," the study's authors report.

The work was headed by bacteriologists Leresche Even Doneilly Oyaba Yinda and Richard Onanga, of Gabon's Interdisciplinary Medical Research Center of Franceville. They characterise the nation’s remarkable biodiversity as a "vast reservoir of unexplored potential active biomolecules."

In a 2022 study, people living in a village close to Moukalaba-Doudou National Park reported that several plants were used both in their community’s traditional medicines and by nearby western lowland gorillas (Gorilla gorilla gorilla).

Testing bark used by western lowland gorillas

To explore the reports in more detail, Oyaba Yinda and fellow researchers assessed bark from four trees for antimicrobial and antioxidant effects, as well as compounds that could be responsible. The trees were the kapok, or fromager, tree (Ceiba pentandra); the ekanhou, or giant yellow mulberry (Myrianthus arboreus); an unidentified ficus subspecies; and African teak (Milicia excelsa).

Each of the four plants displayed antibacterial activity against at least one strain of multidrug-resistant Escherichia coli. Crude bark extract from the fromager tree demonstrated "remarkable activity" against every multi-drug-resistant E. coli placed in its beaker.

Among the four plants, the ficus subspecies and African teak produced the most powerful antioxidant activity. The team found that the method of preparation mattered: antioxidant levels differed depending on whether the bark extract had been dissolved in ethanol or water.

All four plants also contained comparatively high concentrations of medicinal compounds, including phenols, alkaloids, flavonoids and proanthocyanidins.

Potential benefits and unanswered questions

According to the authors, these characteristics may support the plants’ traditional medicinal use for diarrhoeal illnesses, conditions associated with excessive production of reactive oxygen species-which antioxidants combat-and diseases caused by E. coli infection.

"Alternative medicines and therapies offer definite hope for the resolution of many present and future public health problems," Oyaba Yinda and colleagues say.

"Zoopharmacognosy is one of these new approaches, aimed at discovering new drugs."

That does not mean people should begin eating bark from these plants. At present, clinical evidence has not established how effective such treatments are or whether they cause side effects.

Nor is it certain that gorillas consume bark from these trees to treat illnesses as humans might. They may instead eat it as an additional food source that happens to provide added benefits.

Nevertheless, the researchers write that "the immunity-enhancing consumption of certain plant items (such as bark) by gorillas could be responsible for their ability to host and control these infectious microorganisms without developing serious disease."

The results also underline the need to protect remaining vegetation in places such as Moukalaba-Doudou National Park. Such areas contain not only a rich diversity of organisms, but also the chemical compounds those organisms produce.

The study was published in PLOS ONE.