A comparative study of chemical compounds and antibacterial activity of medicinal plants of Dracocephalum Lindbergii Rech.f and Dracocephalum subcapitatum (kuntze) Lipsky growing in North Khorasan province, Iran

Background: A number of aromatic medicinal plants used for treating infection disease have been mentioned in different phytotherapy manuals due to their availability, fewer side effects, and reduced toxicity.Dracocephalum L is one of the most important genuses of Lamiaceae.The aim of our study was to evaluate the chemical compositions of Dracocephalum Lindbergii Rech.fand Dracocephalum subcapitatum (O.kuntze) Lipskyand there is antimicrobial activites. Methods: Two species of Dracocephalum (Dracocephalum Lindbergii Rech.fand Dracocephalum subcapitatum (O.kuntze) Lipsky ) were collected at North Khorasan province.Extracting the essential oil of the aerial parts of the plant was done through the method of hydrodistillation using Clevenger, and the identification of the essential oils components were carried out through GC-MS. The antibacterial activity was performed against three human pathogenic bacteria including:Escherichia Coli,Staphylococcus aureus, Bacillus atrophaeuse, using disk diffusion method. Results: Forty-two components were identified in the essential oil of the species Deracocephalum Lindbergii Rech.f., representing 90.69% of the total oil. The highest percentage of the components belongs to β-ocimene with 17.58%. Thirty components were identified in the plant Deracocephalum subcapitatum (O.kuntze) Lipsky, representing 87.24% of the total oil, in which the highest percentage belongs to β-ocimene with 24.45%. The antibacterial effects showed that the bacteria of Bacillus atrophaeus and Staphylococcus aureus with the diameter inhibition zones of 29 and 33 mm were the most sensitive. In addition, the essential oil of D.subcapitatum (O.kuntze) with a diameter of 33 mm inhibition zone had the highest antibacterial activity against Staphylococcus aureus bacteria. Conclusion: Based on the results of this study,the chemical variations of the volatile oils  of two Dracocephalum  species might be correlated with geographical regions and enviromental conditions play a significant role in biosynthesis of the components of the oil. Also,The results of the antibacterial examination of the essential oil s of the studied species can lead to the discovery of new antibacterial agents.