Chemical Composition and Antibacterial Activity of the Essential Oils Extracted From 4 Medicinal Plants (Labiatae) of Kerman, Iran

In many parts of the world, a rich tradition of using herbal medicine have been formed through history for treating many infectious diseases. Because of the side effects and the resistance that pathogenic microorganisms build against the antibiotics, much recent attention has been paid to extract biologically active compounds from plant species used in herbal medicine. The aim of this study was to determine the antibacterial activity of four medicinal plants’ essential oils from Labiatae family – Salvia macrosiphon, Rosmarinus officinalis, Dracocephalum polychaetum, and Origanum vulgare – on four pathogenic bacteria as well as identify their chemically active compound. The essential oil was extracted using hydro-distillation method. Then, analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC/MS) and compounds were identified. The antibacterial activity of the oil was evaluated using agar disc diffusion method. Minimum inhibitory concentration (MIC) and Minimum Bactericidal Concentration (MBC) were determined in a broth dilution assay. Most of the evaluated bacteria species were sensitive to the oils. MICs and MBCs showed that these 4 plants relatively had high efficacy against bacteria. More than 90% of the chemical contents of the oils was determined. The obtained results suggest and justify using the indigenous plants’ essential oils in traditional medicine as a treatment for microbial infections or as a preservative in food.