Cymbopogon distans: A source of essential oil with potential antibacterial, antifungal, and mosquito-repelling properties

The essential oils have become increasingly popular in recent years due to their potential as natural antimicrobial agents and a means of controlling mosquitoes. This study explored the chemical composition and antibacterial, antifungal, and mosquito-repellent properties of Cymbopogon distans (Nees ex Steud.) Wats (Poaceae) is a less explored aromatic plant distributed in the Himalayas. The fresh biomasses of C. distans and two commercially grown Cymbopogon species, namely C. flexuous and C. martini were submitted to hydrodistillation to extract their essential oils. Gas chromatography-flame ionisation detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS) analyses revealed the presence of citral, geraniol, and geranyl acetate as major constituents of C. distans. The essential oils of C. flexuous and C. martini were dominated by citral and geraniol, respectively. Antibacterial and antifungal activities of C. distans essential oil were evaluated using disc diffusion and micro-dilution methods and compared with the essential oils of C. flexuous and C. martini. C. distans essential oil showed a broader spectrum of potent antibacterial and antifungal activities (minimum inhibitory concentration: 0.41 mg/ml and minimum bactericidal concentration/minimum fungicidal concentration: 0.82 mg/ml) against the test strains. C. distans essential oil, in combination with norfloxacin and penicillin G showed synergistic interactions (fractional inhibitory concentration ≤0.5) against Staphylococcus aureus and Staphylococcus epidermidis. C. distans essential oil showed a repellent effect against Aedes aegypti (73.3 %) that was comparable to C. winterianus essential oil (75.6 %). This study suggests that C. distans essential oil may be a promising natural candidate for developing new herbal therapies for combating microbial infections and mosquito-borne diseases.