investigating the chemical composition of rosemary essential oil of ten populations from iran and its antibacterial activity on two types of gram positive and negative bacteria

Antibiotics, as one of the most important medicines against infectious diseases, have an important role in curing diseases (1). despite researches to produce new antibiotics, with the increase of antibiotic resistance, efforts to find alternatives have continued. among these alternatives, plant essential oils (eos) have been particularly important (2). rosemary eo is beneficial due to its antibacterial and antifungal contents (1). in this study, the chemical compositions of ten populations of rosemary in different regions of iran including tehran, kerman, khorram abad, kermanshah, tabriz, durood, borujerd, malayer, jowkar and bisotun were investigated. among the five main compounds of each population that had the highest percentage (gas chromatography mass spectrometry method), α-pinene was present in all populations. also, 1,8-cineole was present in all the regions except for borujerd. therefore, 1,8-cineole and α-pinene were the main compounds of rosemary eo (1, 2, 3). it is suggested to conduct more research on the effects of rosemary eo from different regions on the common bacteria and to identify the most efficient eo. according to the results of the studies, rosemary eo is more effective on gram-positive bacteria. the main reason for this effect is the absence of an outer membrane made of lipopolysaccharide which makes gram-positive bacteria vulnerable to the penetration of eos. although the outer membrane of gram-negative bacteria is also permeable to some hydrophobic compounds with low molecular weight, it can explain the difference between eos performance on gram-positive and negative bacteria.