Biochemical Composition of Curcuma longa L. Accessions

Abstract

The essential oil composition and total phenolic content (TPC) of curcuminoids were studied in rhizomes of nine Curcuma longa L. accessions. Curcuminoids, present in commercially available turmeric rhizomes, play vital roles in various pharmacological activities. A simple, rapid, and sensitive high performance liquid chromatography photodiode array (HPLC-PDA) method was optimized for simultaneous determination of curcuminoids, namely, a mixture of curcumin, demethoxy curcumin (DMC), and bisdemethoxy curcumin (BDMC) in rhizomes of C. longa. Chromatographic separation was performed on an RP C18 column within 13 minutes (11.4 to 12.95 minutes). Elution was accomplished by the application of acetonitrile and 1.5% acetic acid in water in a gradient system with flow rate of 2.0 mL min⁻¹. PDA was employed for qualitative and quantitative analysis. The calibration curves were found linear (0.99) for all cucuminoids; the limit of detection and quantification ranged between 1.01 µ g mL⁻¹ to 1.16 µ g mL⁻¹ and 2.30 µ g mL⁻¹ to 3.05 µ g mL⁻¹, respectively, while recovery values ranged between 97.97% to 98.32%. The amount of curcumin varied from 0.46% to 2.17%, DMC from 0.13% to 0.92% and BDMC from 0.06% to 0.52%. The validated method was successively used to determine the above compounds in C. longa rhizomes. The TPC in rhizomes ranged from 14.12 mg g⁻¹ to 27.72 mg g⁻¹. The chemical composition of rhizome essential oil, analyzed by gas chromatography mass spectrometry (GCMS,) showed large variations in major compounds like ar-tumerone (7.31–38.66%), β-curcumene (1.58–24.53%), and curlone (1.55–15.97%).

Keywords:

• Curcuma longa
• Curcuminoids
• Essential oil
• GCMS
• HPLC-PDA
• TPC

Notes

^a The retention times (t_R) in minutes are the mean values of 10 replicates.

^b correlation coefficient.

– Not detected.