Optimization of Polyphenol Extraction From Securidaca inappendiculata Hassk. Using Response Surface Methodology and Evaluation of Its Antioxidant Potential.

Natural polyphenols extracted from Securidaca inappendiculata (SI) Hassk have been confirmed as the primary active ingredients responsible for its anti-rheumatoid arthritis (RA) effects. This study aims to optimize the extraction of polyphenols from SI using response surface methodology, characterize their composition via UHPLC-QE-MS, and assess the bioactivity of phenolic-rich constituents from SI (PFS). The results showed that the optimal extraction yield of polyphenols from SI was 15.03 ± 0.90 mg/g under specific conditions: an ethanol concentration of 90%, a liquid-solid ratio of 40 mL/g, an extraction temperature of 50°C, and an ultrasound power of 500 W. The dichloromethane extract of SI contains various plant polyphenols, including xanthones, phenolic acids, phenylpropanoids, coumarins, and flavonoids, with xanthone derivatives being the most predominant. Antioxidant experiments indicated that PFS dose-dependently enhanced the scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) radicals. In lipopolysaccharide-induced RAW 264.7 cells, PFS significantly reduced levels of malondialdehyde (MDA) and reactive oxygen species (ROS), while enhancing activities of catalase (CAT) and superoxide dismutase (SOD). All clues indicate that polyphenols play an important role as the main active ingredients in SI, and their antioxidant activity is highly likely to contribute to SI's anti-RA effect.