Behrooz Dousti - Department of Biology, Khorramabad branch, Islamic Azad University, Iran
Fatemeh Nabipor - Department of Biology, Khorramabad branch, Islamic Azad University, Iran

Background and Aim : Increasing resistance to antibiotics, drug side effects and extracting new and low-risk compounds from medicinal plants, caused researchers to more studies treatment effects of plants active secondary metabolites. The aim of the this study is to evaluate the total phenolic and flavonoid contents and antibacterial activities of different concentrations of various extracts of Onosma Chlorotricum compared with two standard Antibiotics.Methods : Total phenolic and flavonoid contents and the antibacterial activity of methanol, n-hexane and aqueous extracts (۵ mg/ml to ۰.۱۵۶ mg/ml final concentration) of Onosma chlorotricum against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia Coli were evaluated using disc diffusion and microdilution methods. Antibiotics Vancomycin and amikacin were used as Positive control and DMSO as negative control. Total phenolic and flavonoid contents of these extracts were determined according to the Folin-ciocalteu procedure and Aluminum chloride colorimetric assay respectively.Results : The results showed that the total phenolic and flavonoid contents of these extracts ranged from ۷۴.۱۲± ۰.۰۵ to ۵۶.۱۰±۰.۱۳ mg GAE/g dry extract and from ۲۳.۲۰±۰.۴۱ to ۱۹.۳±۰.۶ mg QE/g dry extract, respectively. The methanol extract with the highest phenolic and flavonoid content showed the highest antibacterial activity against all tested bacterial strains with the highest inhibition zone of (۲۱±۰.۷) and the lowest MIC and MBC values ۷۸.۱۲ ?g/ml for S.aureus.Conclusion : The antibacterial effects and the total phenolic content of Onosma chlorotricum Boiss were remarkable and should be investigated more in future studies. we offer the effects of this extracts on wound healing in an animal model and to be investigated via in vivo and clinical models.

Phenolic content, Flavonoid content, Antibacterial, Onosma chlorotricum