Headspace GC–MS volatiles profiling in leaves of 4 Cymbopogon species and their vapor-phase antibacterial effects

Aromatic Cymbopogon grasses are valued for their culinary and medicinal applications, yet most species remain underexplored compared to C. citratus. In this study, the aroma profile of leaves from 4 Cymbopogon species (C. citratus, C. nardus, C. martini and C. procerus) was characterized using headspace-SPME-GC-MS-based analysis alongside lemongrass essential oil identifying 44 volatiles. C. citratus, C. nardus, C. procerus, and lemongrass oil were rich in aldehydes, predominantly citral isomers, neral (24.6–33.9%) and geranial (38.5–57.1%), while geraniol alcohol (86.6%) characterized C. martini. Multivariate data analyses were utilized for species classification but failed to reveal geographical origin. The vapor-phase antibacterial activity of Cymbopogon leaves, lemongrass oil, and citral was evaluated against multidrug-resistant ESKAPE pathogens (Enterococcus faecalis, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter cloacae). Each specimen revealed inhibition of all Gram-positive and Gram-negative bacteria except E. faecalis, for which only one C. citratus (ctr3) and lemongrass oil were effective at vapor-phase minimum inhibitory concentration (VP-MIC) 1.57 mg/mL and 0.1 µg/mL, respectively. Lemongrass oil showed higher activity than citral against K. pneumoniae (0.05 vs. 0.1 µg/mL) and A. baumannii (0.08 vs. 0.12 µg/mL). The composition of C. procerus aroma is revealed for the first time along its antibacterial effects.