Ultrasonic extraction of polyphenols from roots of Ilex asprella: Structural characterization, antioxidant, antimicrobial, anti-inflammatory, and anti-hyperlipidemic activities.

Plant polyphenols have gained increasing attention due to their abundant and powerful biological activities. However, polyphenols from roots of Ilex asprella (RIAPs) remain largely unexplored, with limited research on their composition and bioactivity, making it necessary to focus on RIAPs. In the present study, single-factor analysis and response surface optimization were performed for the extraction of RIAPs via an ultrasonic bath extraction method. The findings demonstrated that at 50 % ethanol concentration, 30 min of ultrasonic time, and 300 W of ultrasonic power, the maximum extraction content of RIAPs was 30.14 ± 0.41 mg/g. Compound and structural analysis via high-resolution liquid chromatography-mass spectrometry (LC-MS/MS) and a Fourier transform infrared (FT-IR) spectrometer confirmed that polyphenols were the majority of compounds comprising RIAPs, in addition to small amounts of alkaloids and trace amounts of other compounds such as amino acids. Scanning electron microscope (SEM) images revealed that RIAPs exhibited a densely reticulated and fragmented microstructure. In addition, bioactivity experiments demonstrated significant antioxidant, antibacterial, anti-inflammatory, and anti-hyperlipidemic activities of RIAPs, supporting their potential pharmaceutical applications. This study provides an experimental foundation for further pharmacological research and potential drug development of RIAPs.