Subcritical water method replacing traditional extracting process to promote the green and efficient extraction of paeonol from peony root bark

Paeonol is a valuable bioactive compound found in peony root bark, with wide applications in food and nutraceutical industries. This study developed an environmentally friendly subcritical water extraction (SWE) method for efficient extraction of natural paeonol. Through single-factor optimization of extraction parameters, the ideal conditions were determined as temperature of 180 °C, solid–liquid ratio of 1:40 g/mL, and extraction time of 40 min, achieving a high yield of 22.87 mg/g, which is 4.64 times and 4.96 times higher than that obtained by traditional steam distillation and ultrasound-assisted extraction, respectively. Results demonstrated that SWE provided significantly higher extraction efficiency and superior product quality. Furthermore, the antioxidant capacity of SWE-extracted paeonol was comprehensively evaluated using multiple in vitro models like FRAP, ABTS, DPPH, superoxide anion radical and hydroxyl radical scavenging assays. All assays consistently indicated its superior activity compared to samples obtained by traditional methods, with the DPPH(2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity being particularly outstanding, reaching 89.07% ± 0.56% at a concentration of 14 mg/ml. This work establishes SWE as a robust, green alternative for paeonol extraction, offering an effective analytical approach for sample preparation in quality control and industrial applications. The method represents a advancement in extraction technology for natural bioactive compounds from plant materials, supporting its potential use as a natural antioxidant in functional food and nutraceutical applications.