Response Surface Methodology to Optimize Supercritical Carbon Dioxide Extraction of <i>Polygonum cuspidatum</i>
Ningjie Ruan, Zhen Jiao, Linglong Tang
Abstract
BACKGROUND: Resveratrol and emodin are abundant polyhydroxy compounds that are found in the Chinese traditional medicinal herb Polygonum cuspidatum and widely used due to their excellent antioxidant properties. OBJECTIVE: This study aimed to obtain the maximum extraction yields of resveratrol and emodin from P. cuspidatum via green extraction. METHODS: The extracts were acquired through supercritical carbon dioxide (SC-CO2) extraction with ethanol as cosolvent. The independent variables of the extraction process, namely temperature (45-55°C), pressure (20-30 MPa), and ethanol content (80-120 mL/L), were optimized by response surface methodology. RESULTS: These variables had marked effects on the yields of resveratrol and emodin. Second-order polynomial mathematical models were developed and applied to predict the optimal extraction conditions (i.e., temperature of 51.8°C, pressure of 25.34 MPa, and ethanol content of 110.83 mL/L). Under these conditions, confirmatory experiments showed that the yields of resveratrol and emodin were 2.564 ± 0.121 and 2.804 ± 0.108 mg/g, respectively. High antioxidant properties, strong free radical scavenging abilities, and good reducing abilities were observed for the extracts. CONCLUSION: Resveratrol and emodin can be successfully extracted from P. cuspidatum by SC-CO2, and RSM can optimize the process. HIGHLIGHTS: The SC-CO2 extraction of resveratrol and emodin from P. cuspidatum was developed, and RSM was successfully used to optimize the extraction parameters and predict the optimal conditions.