Synergistic antibacterial activity of Bunium persicum and Cuminum cyminum essential oils

Phytomedicines derived from plants as single or poly herbal preparations have shown great promise in the treatment of infectious diseases. Many studies have been carried out to date in order to extract essential oils (EOs) for screening their antimicrobial activity. However, there has not been sufficient research on the combinations of these products for their antimicrobial activity. In this study, the EOs of Bunium persicum (Kerman or black Zireh, i.e. balck cumin) and Cuminum cyminum (cumin) were obtained by hydrodistillation of the plants. The EOs were subsequently analysed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC/MS). The main constituents of Bunium persicum were γ-terpinene (44.2%), cuminaldehyde (16.9%), γ-terpinen-7-al (10.5%) and p-Cymene (8%). Furthermore, the main constituents of Cuminum cyminum were found to be Cuminal (36.31%), cuminic alcohol (16.92%), γ-terpinene (11.14%), safranal (10.87%), p-cymene (9.85%) and β-pinene (7.75%).

EOs of the plants were evaluated for their individual and combined antibacterial activities against several pathogenic bacteria, namely Staphylococcus aureus, Bacillus cereus, Escherichia coli O157H7, Salmonella enteritidis and Pseudomonas aeruginosa. Results revealed promising antibacterial activities against most pathogens using broth microdilution method. Maximum activity of the tested essential oils were observed to be against Staphylococcus aureus and Bacillus cereus and their Minimum Inhibitory Concentrations (MICs) were determined to be 31.2 and 125µg/ml respectively. Combinations of the essential oils showed an additive antibacterial effect against most tested pathogens especially Pseudomonas aeruginosa.