Berberis vulgaris is rich in berberine, an isoquinoline alkaloid, with antidiabetic activity, often used topically for skin-related problems. The aim of this work was to develop a "green" method for berberine extraction using mixtures of water with glycerol, a non-toxic, environmentally-friendly solvent. Response surface methodology based on Box-Behnken design was used to optimize the experimental conditions for ultrasound-assisted extraction of berberine and anti-radical components from B. vulgaris root bark. The independent variables were temperature (X1), glycerol concentration (X2), and ultrasound power (X3), while the responses were berberine concentration and DPPH radical scavenging activity of the extracts (RSA IC50). The response values of the extracts prepared at optimum conditions were (response, X1, X2, X3): berberine yield (145.5 μg/mL; 80 °C, 50%, 144 W) and RSA IC50 (58.88 μL/mL; 80 °C, 30%, 720 W). The observed values deviated from the predicted values by -3.45% and 6.42% for berberine and RSA IC50, respectively, thus indicating the validity of the selected models. The prepared extracts demonstrated antioxidant, anti-melanogenic, and anti-inflammatory activity, as well excellent α-glucosidase and α-amylase inhibitory activity. The displayed biological properties and lack of glycerol toxicity makes the prepared extracts suitable for direct inclusion into antidiabetic and dermatologic food supplements and topical products.
Keywords: Berberis vulgaris; berberine; glycerol; green extraction; response surface methodology.