Anti-oxidant and anti-inflammatory activities of ultrasonic-assistant extracted polyphenol-rich compounds from Sargassum muticum

Polypehnol is an important, potentially bioactive component of Sargassum muticum. In this study, ultrasonic assisted extraction of polyphenol-rich substances was performed using a 38% ethanol solution at a solid:liquid ratio of 1:30 at 68°C for 32 min, determined by single-factor and response surface methodology (RSM) optimization. The content of polyphenol was 5.66 mg/g in the crude extract. Further extraction showed that the polyphenol mainly distributed in ethyl acetate (SKEE) and water phases (SKEW). The anti-oxidation test by electron spin resonance (ESR) spectrum showed that the SKEE had the strongest scavenging activity on DPPH (1,1-diphenyl-2-picrylhydrazyl) and alkyl radicals. SKEE was shown non-cytotoxic but could inhibit the generation of cellular ROS, showing protective effects in H₂O₂ and AAPH-induced Vero cells and UV-B irradiated HaCaT cells. SKEE also significantly inhibited the release of NO of LPS-induced RAW 264.7 cells. Therefore, the polyphenol-rich extracts in ethanol and ethyl acetate showed excellent anti-oxidant and anti-inflammatory activities, which is beneficial to the development of high-value bio-substances.