OPTIMAL EXTRACTING CONDITIONS FOR FLAVONOIDS IN FRUTUS AURANTII IMMATURUS BY RESPONSE SURFACE METHODOLOGY

Studies were made on extracted flavnonids from Frutus aurantii immatures by microwave-assisted extraction, and optimized the extracted factors. The effect of different ethanol concentrations, ratio of solvent to material, extraction time and microwave frequency on yield of total flavonoids and dry extraction ratio were discussed. The Box-Behnken design was applied to fit a response surface function, which based on the one- variable-at-time design. Through the function we can get the optimum extracting conditions. the optimal levels for obtaining 41.39 % total flavonoids and 49.0 % dry extraction ratio were as follows: The ethanol concentration is 70 %, the ratio of solvent to material is 40∶1 (mL∶g), the microwave frequency is 385 W, and The extraction time is 1.5 min. The Box -Behnken design can be used on the extraction of flavnonids from Frutus aurantii immatures, and the result is better than that in the one-variable-at-time design.