Abstract
BACKGROUND: Bacterial pathogens have evolved numerous defense mechanisms against commercial antimicrobial agents, and their resistance to most of the available antimicrobials is increasing. Medicinal plants are a potential source of antimicrobial agents during the spread and emergence of infectious disease caused by resistant microorganisms. The aim of this study was thus to investigate the antimicrobial activity and acute toxicity of 80% methanol extracts of leaves of Artemisia absinthium, seeds of Datura stramonium, and fruit of Solanum anguivi. MATERIALS AND METHODS: The 80% methanol extracts were prepared by cold maceration. Antimicrobial activity was evaluated against five bacterial species using agar-well diffusion at concentrations of 125, 250, and 500 mg/mL in the presence of positive and negative controls. Minimum inhibitory concentration was determined by broth dilution. The acute toxicity study was done following OECD guidelines. RESULTS: The 80% methanol extract of the fruit of S. anguivi exhibited better activity against most of the bacterial strains, of which Salmonella enterica serovar Typhimurium was found to be the most susceptible, with minimum inhibitory concentration and minimum bactericidal concentration of 1.3 mg/mL and 1.95 mg/mL, respectively, while the seed extract of D. stramonium showed the least activity against most test organisms. The acute toxicity study showed that all three plants had an LD(50) >2,000 mg/kg body weight, and were thus safe. CONCLUSION: The results of this study revealed that the methanol extracts of the three plants (A. absinthium, D. stramonium, and S. anguivi) had different degrees of antibacterial activity against the selected pathogenic bacteria and were safe at higher doses, thus being of great potential to be developed as antibacterial agents. The study also provided scientific evidence to support the continued traditional use of these medicinal plants by communities in different parts of Ethiopia to treat infectious diseases.