Assay-Guided Extraction and Kinetics of Radical Scavenging Activity of Curcumin from the Rhizome of Curcuma longa Linn

Abstract

Extraction of phytoceuticals from medicinal plants need to be optimized to produce standardized, dose-dependent and reliable extracts to meet food or drug administration regulations for translation into approved nutraceutical or pharmaceutical products. Effect of selected limiting extraction variables on yield and antiradical activity of curcumin-rich extract from Curcuma longa rhizomes was investigated. Assay-guided response (free radical scavenging activity) was used to determine the optimized set of extraction parameters. Curcumin-rich extract was produced using solvent boiling process at 65 oC with absolute methanol of weight ratio 1:50 (w/v) within 1 h. Relative radical scavenging activity of the extract derived using the optimized set of parameters recorded an IC50 of 497 μg/ml and its total antiradical capacity determined within 6 h (76 - 85 % at a concentration of 400 – 600 μg/ml) was not significantly different from that of commercially available natural curcumin used as reference. Time-dependent kinetic analysis revealed an initial fast burst in rate of activity (2.27 – 7.77 min-1) followed by a slow reaction rate in a steady second phase (0.12 – 0.54 min-1). Conclusively, appreciable amount of curcumin-rich extract of enhanced antiradical activity was extracted from the rhizome of C. longa using assay-guided procedure.