Pharmacological and behavioral investigation of putative self-medicative plants in Budongo chimpanzee diets.
Level 5 - mechanism / opinion, no new human data
In vitro laboratory assays combined with observational non-human animal field data.
PubMed 38900778 · doi:10.1371/journal.pone.0305219
What was done
Researchers observed two habituated wild chimpanzee communities in Budongo Forest, Uganda, over eight months to identify putative self-medication events associated with illness, injury, high parasite loads, or abnormal urinalysis. They collected 17 botanical samples across 13 plant species (nine trees and four herbaceous plants) associated with behaviors like bark feeding, dead wood eating, and pith-stripping. Three extracts of different polarities (n-hexane, ethyl acetate, and methanol/water) were prepared per sample and evaluated in vitro for growth inhibition against multidrug-resistant clinical bacterial isolates (including ESKAPE strains) and for anti-inflammatory cyclooxygenase-2 (COX-2) inhibition.
What was found
In antibacterial screens, 45 of 53 extracts (88%) showed 40% or greater growth inhibition at 256 μg/mL, and 41 of these (91%) maintained activity at 256 μg/mL or lower in dose-response assays. All plant species inhibited Escherichia coli growth. Alstonia boonei dead wood n-hexane extract exhibited the strongest antibacterial activity against Staphylococcus aureus (IC50: 16 μg/mL; MIC: 32 μg/mL) and Enterococcus faecium (IC50: 16 μg/mL; MIC: >256 μg/mL). Khaya anthotheca bark and resin methanol-water extract showed strong activity against E. faecium (IC50: 16 μg/mL; MIC: 32 μg/mL) and pathogenic E. coli (IC50: 16 μg/mL; MIC: 256 μg/mL). In anti-inflammatory screens, 17 of 51 tested extracts (33%) showed 50% or greater COX-2 inhibition at 5 μg/mL, with highest potency in K. anthotheca bark/resin (IC50: 0.55 μg/mL) and the fern Christella parasitica (IC50: 0.81 μg/mL).
Why it matters
This study provides pharmacological evidence for zoopharmacognosy by demonstrating that plants selected by wild chimpanzees during illness or injury exhibit potent in vitro antibacterial and anti-inflammatory properties.
Limits
All pharmacological data are from in vitro assays, with no assessment of in vivo absorption, bioavailability, efficacy, or toxicity in chimpanzees. The botanical dataset was limited to 17 samples from 13 species collected over eight months, and the total number of individual chimpanzees studied was not reported in the abstract.
Cited by
- supports Research shows chimpanzees instinctively select and chew specific polyphenol-rich plants to heal wounds when injured.