Evaluation of Antibacterial Effect of Aqueous, Hydro- Alcoholic and Alcoholic Extracts of Morus nigra on Gram-Positive and Gram-Negative Bacteria

Background: Microbial resistance to antibiotics has led to serious efforts to discover novel drugs, which is why there is so much interest in the use of herbs. Therefore, the aim of this study was to investigate the antibacterial effect of aqueous, hydro-alcoholic, and alcoholic extracts of Morus nigra in comparison with some common antibiotics. Method: In this experimental study, the zone of inhibition, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the Morus nigra extracts against Staphylococcus epidermidis, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus mutans and Streptococcus pyogenes were determined using the disk diffusion and broth macro-dilution methods. Statistical analysis was performed using the ANOVA test by SPSS software. Results: The results of this study showed that all studied strains were sensitive to different extracts of Morus nigra. The highest antibacterial effect was related to the aqueous extract of Morus nigra, which created an inhibition zone with a diameter of 22.25 against Streptococcus mutans and Streptococcus pyogenes. The lowest inhibition zone (9 mm) was related to the alcoholic extract of Morus nigra against Pseudomonas aeruginosa. The MIC values of different extracts of Morus nigra against test bacteria varied from 0.78 to 3.12 mg/ml and MBC values were between 3.12 and 50 mg/mL. Conclusion: Based on the findings of this study, the aqueous extract of Morus nigra has shown strong bactericidal properties against all studied bacterial strains, which indicates its potential for therapeutic application.