Chemical profiling and antimicrobial activity of essential oil from Curcuma aeruginosa Roxb., Curcuma glans K. Larsen & J. Mood and Curcuma cf. xanthorrhiza Roxb. collected in Thailand

Objective: To investigate chemical constituents and new antimicrobial agents among essential oils from the rhizomes of Curcuma aeruginosa (C. aeruginosa) Roxb., Curcuma glans K. Larsen & J. Mood and Curcuma cf. xanthorrhiza Roxb. Methods: The essential oils were obtained by hydro-distillation and analyzed by gas chromatography/mass spectroscopy. Agar-well diffusion assay was used to study the antimicrobial activity and also broth-micro dilution techniques were examined for minimum inhibitory concentration (MIC) against four bacterial strains and yeast. Results: The gas chromatography/mass spectroscopy analysis showed monoterpenes predominantly (88.53%) in the rhizome oil of Curcuma cf. xanthorrhiza. Sesquiterpenes (50.10%) was the most abundant component in the essential oil of C. glans, while monoterpenes (45.55%) and sesquiterpenes (45.81%) were found in C. aeruginosa with a significant amount. The major components of C. aeruginosa were characterized as camphor (29.39%) and germacrone (21.21%). Germacrone (15.76%), beta-pinene (9.97%) and camphor (9.96%) were found as major compounds in the rhizome oils of C. glans while alpha-terpinolene (24.86%) and p-cymen-7-ol (12.17%) were found as major compositions in Curcuma cf. xanthorrhiza. The essential oils were tested against four bacterial strains and yeast. As a result, the rhizome oil of C. aeruginosa exhibited potent activity against Staphylococcus aureus [inhibition zone (21.94 +/- 0.24) mm, MIC 125 mg/mL], Bacillus cereus [inhibition zone (20.83 +/- 0.36) mm, MIC 125 mg/mL], and Candida albicans [inhibition zone (11.60 +/- 0.30) mm, MIC 250 mg/mL]. Conclusions: The essential oils from three Curcuma species possessed greater activity against the gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) than gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). The results suggest that the essential oils from the fresh rhizome of Curcuma spp. might be a potential source of natural antimicrobial substances.