LAUSR

Abstract 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 anti-microbial 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%), β -pinene (9.97%) and camphor (9.96%) were found as major compounds in the rhizome oils of C. glans while α -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 μg/mL], Bacillus cereus [inhibition zone (20.83 ± 0.36) mm, MIC 125 μg/mL], and Candida albicans [inhibition zone (11.60 ± 0.30) mm, MIC 250 μg/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.