Deeper insight into the volatile profile of essential oil of two Curcuma species and their antioxidant and antimicrobial activities

Essential oil of Curcuma angustifolia Roxb. and Curcuma zedoaria (Christm.) Rosc. are gaining increasing interest worldwide due to its medicinal and cosmetic application, however, the chemical constituents of their essential oil are not well explored. Therefore, the present research aims to obtain a deeper understanding of the volatile composition of two important Curcuma species viz. C. angustifolia and C. zedoaria using two-dimensional gas chromatography with time-of-flight mass spectrometry (GC x GC-TOFMS). A total of 206 different compounds were detected (139 in C. angustifolia and 147 in C. zedoaria), including alkanes, alkenes, aldehydes, alcohols, esters, ketones, monoterpenes, sesquiterpenes, diterpenes, phenylpropanoids, furans, and fatty acids. The major compounds were epicurzerenone (29.62 %), curzerenone (10.79 %), and trans-beta-terpineol (6.12 %) in C. angustifolia and curzerenone (17.72 %), gamma-Eudesmol acetate (15.85 %), and germacrone (6.50 %) in the C. zedoaria rhizome essential oil. Two-dimensional gas chromatography with time-of-flight mass spectrometry tentatively identified about three times more constituents than those identified by one dimensional gas chromatography with time-of-flight mass spectrometry (GC-TOFMS). The result showed the superiority of GC x GC-TOFMS to detect a higher no. of trace constituents and separate co-eluting components that remain unresolved on a single GC column. Both the essential oil exhibited promising antioxidant activity and were comparable to that of positive standard ascorbic acid and butylated hydroxytoluene (BHT). The essential oil of both the Curcuma species exhibited good antimicrobial activity against five bacterial, three fungal and yeast strains; however, C. zedoaria essential oil displayed a strong inhibitory effect against Candida albicans (6.25 mu g/mL) and Staphylococcus aureus (6.25 mu g/mL). The present study provides significant information on the chemical profile and bioactivity studies of rhizome essential oil of Curcuma angustifolia and Curcuma zedoaria.