Optimization of Ethanol Extraction Conditions for Functional Components from Lespedeza cuneata Using Response Surface Methodology

Abstract This study was conducted to monitor the quality characteristics of Lespedeza cuneata ethanolic extracts, by a response surface methodology. The independent variables were the extraction temperature (35～95℃), extraction time (2～10 hr), and ethanol concentration (10～90%). The coefficients of the determinations (R2) were 0.8562 (p<0.1), 0.9787 (p<0.01), and 0.8344 (p<0.1) in total polyphenol, total flavonoid, and electron donating ability, respectively. The electron donating ability and nitrite scavenging effect were improved with an increase of ethanol concentration, rather than the extraction temperature. ORAC (Oxygen Radical Absorbance Capacity) with extraction conditions was 1,636.47～2,696.99 μmoles TE/g, and was increased with the increase of extraction temperature and 40～60% of ethanol concentration. Estimated conditions for the maximized extraction including the yield, total polyphenol, electron donating ability, nitrite scavenging effect, and ORAC, were 60～68℃ in extraction temperature, 6～7 hr in extraction time, and 38～60% in ethanol concentration.Key words : Lespedeza cuneata, ethanol extract, antioxidant, optimization, RSM