Determination of antimicrobial and anti-MRSA activity of Helleborus orientalis extracts

The aim of this study was to determine the antimicrobial activity of ethanol and water extracts of Helleborus orientalis against standard pathogenic microorganisms and the anti-MRSA activity against clinically sourced Methicillin Resistant Staphylococcus aureus (MRSA) strains. The broth microdilution method was used to assess antimicrobial activity. The tested strains were exposed to extract concentrations ranging from 12.5 to 0.006 mg/mL. The ethanol extract showed antibacterial activity against standard Gram-positive bacterial strains, including Staphylococcus aureus and Sarcina lutea, at a dose of 3.12 mg/mL, while the most effective strain was the Gram-positive Bacillus cereus (Minimum Inhibition Concentration (MIC) 0.78 mg/mL). No activity was detected against Gram-negative bacteria such as Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Salmonella enteritidis. It was also observed that the ethanol extract did not exhibit antifungal activity against the yeast strain Candida albicans. However, It demonsrated anti-MRSA activity at a concentration of 3.12 mg/mL against all MRSA strains tested (MIC 6.25 mg/mL, except for MRSA strain 6). In contrast, the water extract showed no antibacterial and antifungal activity against any of the standard bacterial strains and yeast strains tested. Similarly, it did not show anti-MRSA activity against the MRSA strains studied. In conclusion It can be stated that the ethanol extract of the Helleborus orientalis is more effective than the water extract, and that the ethanol extract is active against Gram-positive bacteria than Gram-negative bacteria.