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 twenty-one 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. Resumen Infecciones bacterianas e inflamación se encuentran entre las enfermedades tratadas por curanderos tradicionales. La Organización Mundial de Salud se ha expresada como altamente interesada en la Medicina Tradicional, y es importante demostrar científicamente que los remedios usados en la medicina popular de veras son terapéuticamente activos. En este trabajo evaluamos la propiedad antibacteriana de 525 muestras de plantas medicinales del Perú septentrional de mínimo 405 especies contra Staphylococcus aureus Rosebach 1884 Escherichia coli (Migula 1895) Castellani & Chalmers 1919, Salmonella enterica Typhi (ex Kauffmann & Edwards 1952) Le Minor & Popoff 1987 e Pseudomonas aeruginosa (Schröter 1872) Migula 1900, usando un método de difusión en agar bajo de condiciones simples de laboratorio en Trujillo, Perú. La meta de este estudio fue de científicamente probar si plantas usadas en la Medicina Tradicional para tratar infecciones mostraron actividad antibacteriana, y para delinear candidatos para estudios futuros de Concentración Inhibitoria Mínima y toxicidad. Ciento noventa y tres extractos etanolicos y 31 extractos en agua mostraron actividad en contra de S. aureus. En 21 casos solo los extractos acuosos fueron eficaces. Ninguno de los extractos acuosos tuvo actividad contra las otras bacterias, y solo 36 de los etanolicos mostraron eficaz contra E. coli, y 3 en cada caso contra S. enterica Typhi e P. aeruginosa. Doscientos veinticinco extractos pertenecieron a especies tradicionalmente usadas como antibacterianas. De estos 73.8% fueron activos. De los 300 extractos de plantas no tradicionalmente usadas contra bacterias, solo 32% tuvieron un efecto positive. Plantas usadas para el tratamiento de infecciones respiratorias, inflamación/infección, heridas, diarrea e infecciones después del parto fueron eficaces en 70-88% de los casos. Plantas usadas para inflamaciones de los riñones y otros desordenes tuvieron una eficaz mucho mas baja en contra de bacterias.