SUPERCRITICAL FLUID EXTRACTION OF FLAVONOIDS FROM SOLANUM MELONGENA Linn. FRUIT AND ITS EVALUATION OF FREE RADICAL SCAVENGING ACTIVITY
Supercritical fluid extraction (SFE) represents an efficient and environmentally friendly technique for isolation of phytoconstituents from different plant sources. The present study is focused on extraction of flavonoids from Solanum melongena Linn fruit using Supercritical fluid (SCF-CO2) technology. The fruit extract containing flavonoids has been reported to have hypolipidemic activity. The objective of this work is to evaluate the SCF extraction of flavonoid from S. melongena L. fruit at different operational conditions and discuss the temperature, pressure and flow rate of CO2 dependence in the extract composition profile. Since Carbon dioxide is a non-polar solvent, ethanol is used as co-solvent to increase the polarity of the fluid. HPLC-PDA determination of flavonoids is done for each condition and the extraction conditions are optimized. Chromatographic conditions employed for determination of flavonoids component in fruit extract for PDA analysis are mobile phase (Methanol: Acetonitrile: Orthophosphoric acid: Acetic acid: Water, 200:100:10:10:200 v/v), at a flow rate of 1mL/min. The optimized SC-CO2 extraction conditions under which maximum yields of flavonoids are obtained are temperature 450 C, Pressure 19.61MPa, co-solvent at 11.5% with a CO2 flow rate 3.0mL/min. Further, in vitro free radical scavenging activity of SFE extract was evaluated by 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging method. Ascorbic acid was used as the reference. SFE extract exhibited promising antiradical effects in a concentration dependent manner. Linear regression analysis was used to calculate IC50 value. Results showed that, the extract exhibited significant DPPH radical scavenging activity with IC50 value of 66.063±0.15 µg/mL.