[Biochemical and antimicrobial activities of salvia officinalis L. and mentha piperita L. essential oils]

ABSTRACT

Although antibiotics are used in conventional treatment of infectious diseases, a lot of unexpected side effects along with resistance to antibiotics appear. Salvia officinalis and Mentha piperita are plants found abundantly in most parts of Iran. In the present study, we extracted and identified the chemical compounds of the essential oils of Salvia officinalis and Mentha piperita. Moreover, the anti-oxidative property, free radical scavenging capacity, and antimicrobial activities of the essential oils of these plants were studied. This study was conducted in the Biotechnology Department laboratories, Agricultural Faculty of Avicina University, Hamadan, Iran, in 2009. The aerial parts of Salvia officinalis and Mentha piperita were harvested in summer, when the plants were in their full blooming stage and dried in the shade. The essential oil of the aerial parts was extracted by hydrodistillation and was analyzed by capillary GC and GC/MS method. The micro-organisms employed in this study were E. coli, S. aureus, S. enteritidis, L. monocytogenes. By employing disc diffusion and tube dilution methods, antimicrobial effects of the oils were studied. Antioxidative property, free radical scavenging capacity, and antimicrobial activities of the oils were also studied. Chemical analysis of the extracts resulted in the identification of 28 and 37 compounds in the essential oils of Salvia officinalis and Mentha piperita respectively. The sensitivity of the bacteria to the oils in order of decreasing the sensitivity was L. monocytogenes, E. coli, S. aureus, and S. enteritidis. The antibacterial properties of the essential oil from Mentha piperita leaves were higher than the oil of Salvia officinalis leaves. Also inhibitions zones of microbial growth were not correlated with the microbicidal kinetics of the oils. This study showed that the herbal essences of Salvia officinalis and Mentha piperita are very active against E. coli, S. aureus, S. enteritidis and L. monocytogenes