Antibacterial compounds of Cymbopogon nardus essential oil exposed by high-performance thin-layer chromatography–direct bioautography

Abstract Essential oil of citronella grass ( Cymbopogon nardus ) was screened for antibacterial compounds by high-performance thin-layer chromatography (HPTLC) combined with direct bioautography using soil bacterium Bacillus subtilis , marine bacterium Aliivibrio fischeri , and plant pathogens Pseudomonas syringae pv. maculicola and Xanthomonas euvesicatoria . The parallel derivatization using HPTLC–anisaldehyde reagent also revealed the bioactive compounds separated with n -hexane–isopropyl acetate (9:1, v/v ), which were analyzed by offline solid-phase microextraction–gas chromatography–electron ionization-MS (SPME–GC–EI-MS) after scraping off and elution. The compounds responsible for the antibacterial effect were identified as citronellal, geranial, neral, geraniol, α-cadinol, and elemol. These compounds inhibited all studied bacterial strains except elemol that demonstrated activity only against B. subtilis and X. euvesicatoria .