Antimicrobial activity of Rosmarinus eriocalyx essential oil and polyphenols:An endemic medicinal plant from Algeria

Objective:To evaluate the antimicrobial potency of Rosmarinus eriocalyx(R.eriocalyx)essential oil and total polyphenols against pathogenic microorganisms.Methods:Antimicrobial activity of R.eriocalyx extracts was assessed by disc diffusion method and minimum inhibitory concentrations determination.Essential oil obtained from endemic rosemary by hydrodistillation was analysed by gas chromatograph/retention index and gas chromatograph-mass spectrometer.Results:An interesting antimicrobial activity was shown by R.eriocalyx extracts.Polyphenols,constituted mainly by flavonoids,were the most effective extract with very low minimum inhibitory concentrations values,ranged between 0.06 and 8.00 mg/mL,while essential oil was less efficient.It should be noted that antimicrobial activities of both R.eriocalyx extracts were more directed against fungi and Gram-positive bacteria than Gram-negative ones,in which Staphylococcus aureus,Enterococcus faecalis,and Candida albicans were the most sensitive strains.Concerning chemical composition of R.eriocalyx essential oil,camphor(37.8%),1,8-cineole(17.4%),camphene(13.3%),and α-pinene(10.9%)were the major compounds.Conclusions:The findings of the present study indicate that R.eriocalyx extracts possess significant bactericidal and fungicidal activities.Because of its richness in essential oil,and especially flavonoids,R.eriocalyx may be a source for effective and safe antimicrobial agents.