Purpose: The antimicrobial effectiveness of ethanolic extract of Quassia amara, Solanum sciadostylis (Sendtn.) Bohs and Artemisia annua on Bacillus subtilis ATCC 6633, Bacillus cereus ATCC 11778, Micrococcus luteus ATCC 9341, Enterococcus faecalis ATCC 51299 and Staphylococcus aureus ATCC 6538 were ascertained using the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC).
Methods: Broth microdilution method in 96-well microplates was used and the inoculum was prepared at the concentration of 10-2 CFU/ml, starting from a 0.5 McFarland. Extract concentrations of 19 - 5,000 µg/ml were evaluated.
Results: The plant extracts showed varied activity on the test organisms with Quassia amara and Artemisia showing a stronger antimicrobial activity of 39 μg/ml and 312 μg/ml, respectively, on Micrococcus luteus compared to MIC of 2,500 μg/ml of Solanum sciadostylis and Artemisia extracts on Staphylococcus aureus and 1,500 μg/ml on both Bacillus subtilis and Bacillus cereus. Staphylococcus aureus exhibited the same MIC (2,500 μg/ml) for all extract analyzed. Quassia amara, Solanum sciadostylis and Artemisia annua extracts did not show any bactericidal activity between the concentrations of 19 – 5,000 μg/ml used for experiment on Bacillus cereus and Enterococcus faecalis. MBCs of Artemisia annua extracts of 1,250 μg/ml was generally lower than that of Quassia amara extracts 2,500 mg/ml on Bacillus subtilis. The MBCs of Quassia amara, Solanum sciadostylis and Artemisia annua extracts on Micrococcus luteus were the same (5,000 μg/ml).
Significance: This study confirms the antimicrobial potential of these plants extracts and supports the use in traditional medicine and would be an interesting source for discovery of novel antibiotics agents from plant sources. This study confirms the antimicrobial potential of these plants extracts and supports the use in traditional medicine and as interesting source for discovery of novel preservatives in food technology.