Proving that traditional knowledge works: The antibacterial activity of Northern Peruvian medicinal plants

Abstract

Bacterial infections and inflammation are among the ailments treated by traditional healers. The World Health Organization has expressed high interest in Traditional Medicine (TM), and it is important to demonstrate scientifically that the remedies employed in folk medicine are indeed therapeutically active. In order to evaluate the antibacterial activity of species used in traditional medicine in Northern Peru, 525 plant samples of at least 405 species were tested in simple agar-bioassays for antibacterial activity under simple laboratory conditions in a private clinic in Trujillo, Peru. Antibacterial activity was investigated against Staphylococcus aureus Rosenbach 1884, Escherichia coli (Migula 1895) Castellani & Chalmers 1919, Salmonella enterica Typhi (ex Kauffmann & Edwards 1952) Le Minor & Popoff 1987, and Pseudomonas aeruginosa (Schröter 1872) Migula 1900. The aim of the study was to scientifically test whether plants used in TM for the treatment of infections showed antibacterial activity, and to delineate a number of candidates for further in-depth study of their Minimum Inhibitory Concentration (MIC) and toxicity. One-hundred-ninety-three ethanolic extracts and 31 water extracts were active against S. aureus. In twentyone cases only the water extract showed activity. None of the aqueous extracts were active against the other three bacteria, with the activity of the ethanolic extracts also much reduced, as only 36 showed any activity against E. coli, and 3 each against S. enterica Typhi and P. aeruginosa. Two-hundred-twenty-five extracts came from species that are traditionally employed against bacterial infections. One-hundred-sixty-six (73.8%) of these were active against at least one bacterium. Of the three-hundred extracts from plants without traditional antibacterial use, only 96 (32%) showed any activity Plants used for respiratory disorders, inflammation/infection, wounds, diarrhea, and to prevent post partum infections were efficacious in 70- 88% of the tests. Plants used for "kidney inflammation" had a much lower efficacy against bacteria and fell within the range of species that are traditionally used to treat other bodily disorders.