Major Compounds and Antimicrobial Activity of Essential Oils from Five Iranian Endemic Medicinal Plants

Background: Essential oils are one of the most active components which can be found in medicinal plants. These compounds which are made up of many different volatile compounds possess antimicrobial activity against various microorganisms and have been used since the earliest reported history. Objective: To investigate essential oils of five plant materials (Artemisia sieberi, Cymbopogon olivieri, Haplophyllum tuberculatum, Salvia macrosiphon, Teucrium polium) for antibacterial activities. Materials and Methods: The GC /MS analyses were carried out on herbal extract using a Hewlett- Packard 6890. For investigating the anti-microbial effect, Streptococcus pneumoniae, Klebsiella pneumoniae, Staphylococcus aureus, Escherichia coli, Staphylococcus epidermidis were used. Results: Main components of each plant were: Cymbopogon olivieri: piperitone (67.79%); Haplophyllum tuberculatum: borneol (25.73%); Salvia macrosiphon: piperitone (33.16%); Teucrium polium: limonene (37.70%) and Artemisia sieberi: piperitone (34.05%). The best antimicrobial activity by agar diffusion method was respectively belonged to Salvia macrosiphon; Artemisia sieberi and the mixture that had more activity than positive standard. Agar dilution method was used to identify MIC and MBC for each essential oil and the mixture. Best results were: Haplophyllum tuberculatum, Cymbopogon olivieri and Teucrium polium that showed MIC and MBC in 5 μL concentration on Streptococcus pneumoniae and MIC in similar concentration on Staphylococcus aureus. Salvia macrosiphon and Artemisia sieberi showed MIC in 5 μL concentration on Streptococcus pneumoniae. The mixture had good activities on Streptococcus pneumoniae and Staphylococcus aureus. Conclusion: our results and previous works indicate that these essential oils have good antimicrobial activity and have potentials for future works in this field.