Screening of Microwave-Assisted-Batch Extraction Parameters for Recovering Total Phenolic and Flavonoid Contents from Chromolaena odorata Leaves through Two-Level Factorial Design

Microwave-assisted-extraction (MAE) of phenolic compounds from Chromolaena odorata leaves was investigated using one-factor-at-a-time (OFAT) and two-level factorial design. The MAE parameters studied were irradiation time (A: 1-5 min); microwave power level (B: 400-800 W); extraction temperature (C: 60-80 degrees C); solvent/feed ratio (D: 8:1-14:1 mL/g); and ethanol concentration (E: 20-60% v/v). The optimum yields of TPC and TFC were 56.13 mg GAE/g d.w. and 44.78 mg QE/g d.w., respectively were achieved from MAE of C. odorata leaf at irradiation time of 2 min, microwave power of 600 W, temperature of 60 degrees C, solvent:feed ratio of 10:1 mL/g, and ethanol concentration of 40% v/v through one-factor-at-time (OFAT) experimental trials. The results obtained from a two-level factorial design experiments demonstrated that only ethanol concentration (20-60% v/v), irradiation time (1-5 min) and microwave power level (400-800 W) had significant effects on the yields of total phenolic content (TPC) and total flavonoid content (TFC) from C. odorata leaves (p < 0.05). However, temperature and solvent/feed ratio was not significant. In addition, the interactions AB (irradiation time and microwave power) and AE (irradiation time and ethanol concentration) contributed greatly to the recovery yields.