Isolation and Characterization of Curcumenotone, a Sesquiterpene from Curcuma aeruginosa Roxb as Antioxidant

Antioxidant compounds are necessary to block the initiation of oxidation chain reactions and inhibit the formation of ROS which are the cause of various diseases. Natural antioxidants can be isolated from various sources: one of which is Curcuma aeruginosa Roxb Rhizome. This study was aimed to isolate and identify the antioxidant compounds from C. aeruginosa Roxb rhizome. To isolate the active compound, the 2,2-diphenyl-1-picrylhidrazyl (DPPH) free radical scavenging activity guide was used. Initially the C. aeruginosa Roxb rhizome powder was macerated with 70 ethanol to produce ethanol extract (EE). The EE was then fractionated gradually by increasing the polarity of solvents to produce n-hexane (HF), ethyl acetate (EAF), ethanol (EF) and insoluble (IF) fractions. EF as the active fraction, was fractionated into 6 fractions (EF.a-f) based on their TLC images. Two compounds (EF.a1 and EF.a2) were isolated from the active fraction (EF.a) by preparative TLC. EF.a2 which appeared as white crystals demonstrated the best activity as DPPH anti radical, having 96.24 purity (HPLC). EF.a2 appeared as a single peak in GC (Rt 12,78), and had a molecular weight of m/z 234. There were 2 absorbtion peaks at 226 nm and 260 nm in Uv-Vis spectrophotometer and absorption bands at 3364, 3314, 2905 and 1653 cm-1 on the FT-IR spectrum. Based on the spectroscopic data (1H-,13C-NMR) and the reported data, the EF.a2 was identified as sesquiterpene, curcumenotone (C15H22O2). The curcumenotone was shown to be a potent antioxidant in the DPPH radical scavenging assay with an IC50 of 53.24±1.51 µg/mL, ABTS radical scavenging assay with an IC50 of 41.33±3.15 µg/mL, and FRAP assay with an IC50 of 37,82±2.02 µg/mL. Copyright © 2023 by Indonesian Journal of Pharmacy (IJP).