Optimization of Surfactant‑Mediated, Ultrasonic‑assisted Extraction of Antioxidant Polyphenols from Rattan Tea (Ampelopsis grossedentata) Using Response Surface Methodology

Background: Rattan tea is a medicinal plant that has been used for many years for the treatment of inflammation, fatty liver, tumor, diabetes, and hyperlipidemia. Objective: A green and novel approach based on surfactant‑mediated, ultrasonic‑assisted extraction (SM‑UAE) was developed for the extraction of antioxidant polyphenols from Rattan tea. A nonionic surfactant Tween‑80 was selected as extraction solvent. The antioxidant activity was measured by total phenolic content (TPC) and ferric‑reducing/antioxidant capacity (FRAC) assay. Materials and Methods: Optimization of extraction parameters including concentration of solvent, ultrasonic time, and temperature were investigated by response surface methodology. The antioxidant activity was measured by TPC and FRAC assay. Results: The optimal extraction conditions were determined as 6.8% (v/v) of aqueous Tween‑80, ultrasonic temperature of 54°C, and ultrasonic time of 28.8 min. Under these conditions, the highest TPC value of 360.4 mg gallic acid equivalent per gram of dry weight material (GAE/g DW) was recorded. Moreover, 6.8% (v/v) of aqueous Tween‑80, ultrasonic temperature of 54.5°C, and ultrasonic time of 28.4 min were determined for the highest FRAC value of 478.2 μmol of Fe2+/g of weight material (μmol Fe2+/g DW). Compared with other methods, the TPC and FRAC values of 313.5 mg GAE/g DW and 389.6 μmol Fe2+/g DW were obtained by heat reflux extraction using ethanol as solvent, respectively, and 343.2 mg GAE/g DW and 450.1 μmol Fe2+/g DW were obtained by UAE using ethanol as solvent, respectively. Conclusion: The application of SM‑UAE markedly decreased extraction time or extraction cost and improved the extraction efficiency, compared with the other methods.