The genus Curcuma, composed of 93 species mainly originating from Asia, Australia, and South America, has been used for medicinal purposes, aromatic, and nutritional values as well as cosmetic. It plays a vital role in flavoring and coloring as well as exhibiting therapeutic agents against different diseases. Nepalese farmers are unaware of the essential oil compositions of Curcuma species, viz. C. aeruginosa, C. zedoaria, and C. longa. The investigation of these three essential oils provides insight into their potential as cash crops and earns a reasonable return from their production. The essential oils were obtained from the rhizomes of each plant by hydrodistillation and subjected to Gas Chromatography/Mass Spectrometry (GC−MS) analysis to identify its volatile chemical constituents as well as chiral GC-MS to identify the enantiomeric distribution of chiral terpenoids. The order of extraction yields were C. longa (0.89%) > C. zedoaria (0.74%) > C. aeruginosa (0.37%). In total, the presence of 65, 98, and 84 compounds were identified in C. longa, C. zedoaria, and C. aeruginosa, representing 95.82%, 81.55%, and 92.59% of the total oil, respectively. The most abundant compounds in C. longa essential oils were ar-turmerone (25.5%), α-turmerone (24.4%), β-turmerone (14.0%), terpinolene (7.2%), β-sesquiphellandrene (5.1%), α-zingiberene (4.8%), β-caryophyllene (2.9%), ar-curcumene (1.6%) and 1,8-cineole (1.3%). The most dominant compounds in C. zedoaria were curzerenone (21.5%), 1,8-cineole (19.6%), curzerene (6.2%), trans-β-Elemene (5.1%), camphor (2.6%), and germacrone (2.3%). The major components in C. aeruginosa were curzerenone (59.6%), germacrone (5.3%), curzerene (4.7%), camphor (3.6%), trans-β-Elemene (2.6%), and β-eudesmol (1.6%). C. zedoaria, and C. aeruginosa essential oil from Nepal for the very first time. This study reports for the first time chiral terpenoids from C. aeruginosa, C. zedoaria, and C. longa essential oil. A chemical blueprint of these essential oils could also be used as a tool for identification and quality assessment.
Keywords: ar-turmerone; curzerenone; enantiomeric distribution; α-turmerone; β-turmerone.