Optimization of microwave-assisted extraction of phenolic compounds and antioxidants from Careya sphaerica Roxb. flowers using response surface methodology

Careya sphaerica Roxb. flowers are good sources of phenolic compounds (PCs) with bioactive properties such as antioxidant activity. The objective of this study was to optimize the extraction parameters for microwave-assisted extraction (MAE) of PCs from C. sphaerica Roxb. flowers, utilizing response surface methodology (RSM) through a central composite design. The extraction of PCs was significantly (p < 0.05) impacted by process variables. The best possible combinations were microwave power (MP) 1000 W, solid to solvent (S-S) ratio 1:100 g: mL, ethanol concentration 40 % v/v, and extraction time 20 s to obtain the maximum extraction yield (EY), extractable phenolic compounds (EPC), DPPH and total flavonoid content (TFC). The maximum EY, EPC, DPPH, and TFC of 70.4 g, 33,504 mg GAE, 24,355 mg GAE and 13,115 mg CE, respectively were obtained per 100 g dry mass. The result suggests that MP and S-S ratio significantly (p < 0.05) affect the extraction of PCs and DPPH. All of the models applied to fit the responses were significant (p < 0.01) and suitable to represent the relationship between independent variables and responses. The study revealed the effectiveness of MAE using RSM for the extraction of PCs from C. sphaerica flowers.