Antimicrobial activity of traditional medicinal plants from Ankober District, North Shewa Zone, Amhara Region, Ethiopia

Abstract

Context: Traditional medicinal plants have long been used in Ethiopia to treat human and livestock ailments. Despite a well-documented rich tradition of medicinal plant use in the country, their direct antimicrobial effects are still poorly known.

Objective: To investigate the antimicrobial activity of 19 medicinal plant species that were selected based on the ethnobotanical information on their traditional use to treat infectious diseases in Ankober District.

Methods: About 23 different ethanol extracts of plants obtained by maceration of various parts of 19 medicinal plant species were studied for potential antimicrobial activity using a broth microdilution method against Bacillus cereus, Bacteroides fragilis, Candida albicans, Clostridium perfringens, Enterococcus faecalis, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella enteritidis, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes.

Results: Plant extracts from Embelia schimperi Vatke (Myrsinaceae) showed the strongest antibacterial activity with a minimum inhibitory concentration (MIC) value of 64 µg/ml against B. cereus, L. monocytogenes, and S. pyogenes. Growth inhibitory activities were also observed for extracts of Ocimum lamiifolium Hochst. (Lamiaceae) against S. pyogenes, and those of Rubus steudneri Schweinf. (Rosaceae) against S. epidermidis at an MIC value of 128 µg/ml. Generally, 74% of ethanol extracts (17 extracts) showed antimicrobial activity against one or more of the microbial strains tested at an MIC value of 512 µg/ml or below.

Discussion and conclusions: Results confirm the antimicrobial role of traditional medicinal plants of Ankober and warrant further investigations on promising medicinal plant species so as to isolate and characterise chemicals responsible for the observed strong antimicrobial activities.

• Activity testing
• ethnomedicine
• plant extracts

Acknowledgements

We are indebted to the inhabitants of Ankober District, particularly the traditional medical practitioners who unreservedly shared with us their knowledge on medicinal plants. Staff members of The National Herbarium (Ethiopia) are also acknowledged for their cooperation at all aspects of the herbarium work. Dr. Henok Lulekal from WDAO, North Shewa, and Sr. Tsehay Aytenew, Hayat Hospital AA, both from Ethiopia, are acknowledged in translating local names of diseases into their English equivalents based on the descriptions of symptoms. Staff members of digital libraries of AAU, UGent, and UNECA are also acknowledged for providing references for this work. We thank Mr Ashenafi Mihrete, Mr Abebe Shewamene, Mr Getu Shewamene, and Mr. Dawit Tewabe for their field assistantship. We also extend our gratitude to administrative officials of Ankober Woreda Development Association, Ankober District, Debre Berhan University, and Increasing People Opportunity (IPO) office in Ethiopia for their support in facilitating the study.