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.