Optimizing the extraction parameters of phenolics and flavonoids from Bouea macrophylla Griff leaves using ultrasound-assisted extraction and evaluating their antioxidant abilities

Abstract Bouea macrophylla Griff is a plant species that primarily thrives in the wet tropical regions of Southeast Asia, such as Indonesia, Myanmar, Malaysia, and Thailand. B. macrophylla leaves contain a potential source of phenolics and flavonoids that exhibit biological activities. This research aimed to maximize the total phenolic and flavonoid contents of B. macrophylla Griff leaves extract using an ultrasound-assisted extraction (UAE) and response surface methodology (RSM) with a four-factor and three-level Box Behnken design (BBD) for optimizing the extraction parameters. The values of four independent variables, namely ethanol concentration (X1), extraction temperature (X2), sample weight-to-solvent volume ratio (X3), and extraction time (X4), were investigated and determined through single-factor analysis experiments, and their optimal values were found to be 47% ethanol concentration, 46°C extraction temperature, 1/69 (g/ml) sample to solvent ratio, and 69 minutes of extraction time. Under the optimized conditions, the total phenolic and flavonoid contents of B. macrophylla Griff leaves were determined to be 15.83 ± 0.05 mg GAE/g and 88.37 ± 0.23 mg QE/g, respectively. These experimental values were found to be close with the expected values. Moreover, this study revealed that UAE resulted in significantly higher antioxidant activity in B. macrophylla Griff compared to traditional extraction methods. The findings suggest that the extract obtained from its leaves through the UAE could be a potential source for various cosmetic or medicinal applications.