Antioxidant and antibacterial activities of Pelargonium asperum and Ormenis mixta essential oils and their synergistic antibacterial effect.

In this work, the chemical composition, the antioxidant, and the antibacterial activities of two Moroccan essential oils less studied, extracted from Pelargonium asperum and Ormenis mixta, were investigated. According to the gas chromatography coupled to mass spectrometry analysis, citronellol (25.07%), citronellyl ester (10.52%), geraniol (10.46%), and buthyl anthranilate (5.93%) were found to be the major components of P. asperum, while O. mixta was mainly composed of D-germacrene (11.46%), 1,8-cineole (10.28%), and cis-methyl isoeugenol (9.04%). Moreover, O. mixta essential oil exhibited an important antioxidant activity being significantly higher than that exhibited by P. asperum oil (P < 0.001). As regards the antimicrobial activity of both essential oils, the zones of growth inhibition and the minimum inhibitory concentration values showed that P. asperum essential oil was more active than that of O. mixta. Thereafter, the impact of the binary combination of essential oils on their antimicrobial effect was investigated against Staphylococcus aureus using the fractional inhibitory concentration index calculation. The results showed a promising synergistic antibacterial interaction between essential oils studied.