Extraction Conditions for Phenolic Compounds with Antioxidant Activities from White Rose Petals

The extract of white rose petals has an antioxidant effect and can be used to treat allergic disease. The purpose of this study was to identify optimal conditions for extracting antioxidative compounds from white rose petals with 2,2-diphenyl-1-picrylhydrazyl scavenging activities. A response surface methodology based on a central composite design was used to investigate the effects of three independent variables: ethanol concentration ($X_1$), extraction temperature ($X_2$), and extraction time ($X_3$). The estimated optimal conditions for obtaining phenolic compounds with antioxidant activities were as follows: ethanol concentration of 42% ($X_1$), extraction time of 80 min ($X_3$), and extraction temperature of $75^{\circ}C$ ($X_2$). The estimated optimal conditions for obtaining flavonoid compounds with antioxidant effects were an ethanol concentration of 41% ($X_1$), extraction time of 119 min ($X_3$), and an extraction temperature of $75^{\circ}C$ ($X_2$). Under these conditions, predicted response values for the phenolic and flavonoid contents were 243.5 mg gallic acid equivalent/g dry mass and 19.93 mg catechin equivalent (CE)/g dry mass, respectively.