Investigation of The Antibacterial Activity Of Rosmarinus Officials and Eucalyptus Parvula Leaves On Six Pathogenic Bacteria

Background: The excessive use of antibiotics has led to the emergence of bacterial resistant strains, which indeed highlighted the need for natural alternatives with antimicrobial properties.
Materials and Methods: Six aromatic plants were screened simply by well diffusion
method. Among them, Rosmarinus officinalis and Eucalyptus parvula were chosen. Then Aqueous, ethanolic, and hydrosol extracts of both plant leaves were dried and brought to powder, and then various concentration of extracts were prepared as (10 mg, 20 mg, and 40 mg per 1 ml) in dimethyl sulfoxide (DMSO) solvent. The antibacterial activity was assessed using the well diffusion method against six bacterial species, which were Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus faecalis, Proteus mirabilis, Klebsiella pneumoniae, and Escherichia coli. Eventually the inhibition zones (IZ) were measured as millimeter by ruler, and the results were compared with the positive control antibiotics (Vancomycin and colistin), and with each other as well.
Results: The results showed that both ethanolic and aqueous extracts exhibited antibacterial activity to various degrees, while the hydrosol extracts showed no activity on all bacteria. The ethanolic extract of Rosemary leaves at the concentration (20mg/ml) demonstrated the highest effectiveness, particularly against S. pneumoniae and K. pneumoniae which had IZ of 24mm and 23.3mm, respectively. Additionally, the antibacterial activity of some extracts was increased with increasing concentrations.
Conclusion: This study suggests that the ethanolic extracts of both Rosmarinus officinalis and Eucalyptus parvula Leaves can be candidate as two promising natural sources of antibacterial compounds for some specific infections.