Optimization of green microwave assisted extraction of propolis with antioxidant evaluation and kinetic modeling

Microwave-assisted extraction (MAE) is an efficient green technique for recovering bioactive compounds from plant matrices; however, its application to African propolis remains poorly explored, particularly with respect to extraction kinetics and relationships between process conditions and composition. This study aimed to optimize MAE of Cameroonian propolis and to investigate its extraction kinetics, chemical profile, and antioxidant activity. Response surface methodology (RSM) combined with a central composite design (CCD) was used to optimize three process variables: irradiation time, irradiation power, and ethanol concentration. Under optimal conditions (75 s, 550 W, 85% ethanol), high total phenolic content (TPC, 1000.87 mg GAE/g extract) and total flavonoid content (TFC, 48.61 mg QE/g extract) were obtained, substantially exceeding the values obtained by conventional maceration. Antioxidant activity assessed by DPPH and FRAP assays demonstrated strong radical scavenging and reducing capacity, with DPPH IC₅₀ values of 0.16 ± 0.02 and 0.048 ± 0.005 mg/mL for the MAE extract and ascorbic acid, respectively, and FRAP values of 780 ± 2.5 and 900 ± 3.0 µmol Fe²⁺/g. LC-MS analysis tentatively identified eleven phenolic compounds, including chlorogenic acid, caffeic acid, quercetin, and kaempferol. Kinetic modeling revealed that extraction followed a second-order model, suggesting a mechanism dominated by rapid initial solubilization followed by slower diffusion-controlled release. Overall, MAE proved to be a rapid and efficient technique for recovering phenolic compounds from Cameroonian propolis while preserving antioxidant activity. By coupling kinetic and mechanistic analysis with phytochemical and antioxidant characterization, this work establishes optimized MAE conditions that can support the valorization of Cameroonian propolis as a functional ingredient.