Chemical compositions and in vitro antimicrobial activity of Cymbopogon nardus on food borne microorganisms

Abstract

Aims: Food borne infections are routinely observed and frequently reported. Cymbopogon nardus, or commonly known as citronella is a tropical plant widely used for aromatherapy and insect repellant. This study aimed to evaluate the phytochemical compositions of C. nardus ethanol extract and its antimicrobial activity on food borne microorganisms. Methodology and results: The plant materials were extracted with ethanol using maceration technique. The ethanol extract obtained was analysed using GC-MS and the most abundant compounds were 6-methyloctahydrocoumarin (31.5%) and 2,4-di-tert-butylphenol (28.7%). On Kirby Bauer assay, the extract showed wide spectrum inhibitory effect on one Gram-positive bacteria (Bacillus coagulans), two Gram-negative bacteria (Proteus mirabilis and Escherichia coli), and one yeast (Candida albicans). All the test microorganisms showed different susceptibility to the extract, where the minimal inhibitory concentrations were ranged from 63 to 250 µg/mL. The inhibitory effect of the extract was bactericidal. In addition, the time kill analysis of the extract exhibited inhibitory effect on P. mirabilis which was concentrationdependent. The C. nardus extract exhibited rapid bactericidal effect on P. mirabilis and lower bacterial counts were obtained with increased extract concentration. Besides, the extract did not exert significant toxicity effect to Artemia salina on brine shrimp lethality assay. Conclusion, significance and impact of study: Therefore C. nardus can be a potential source of safe and effective antimicrobial agent to combat food borne infections.