Optimization of Extraction of Total Terpenoids from Phellinus igniarius Using Response Surface Methodology and Evaluation of Their Antioxidant Activity.

Phellinus igniarius is a medicinal fungus rich in terpenoids with potential biological activities. In this study, the P. igniarius terpenoid-enriched extract (PITT) was optimized using single-factor experiments combined with response surface methodology based on a Box-Behnken design. The optimal extraction conditions were determined as extraction temperature 64 °C, extraction time 21 min, ethanol concentration 78%, and liquid-to-solid ratio 20 mL/g, yielding a total terpenoid content of 7.078 mg/g. The chemical profile of PITT was characterized by liquid chromatography-tandem mass spectrometry (LC-MS/MS), revealing the presence of multiple putative terpenoid compounds, including betulin, curdione, and several sesquiterpenoids. The antioxidant activity of PITT was evaluated using DPPH, ABTS, and hydroxyl radical scavenging assays, showing dose-dependent effects. Furthermore, an H2O2-induced oxidative stress model in RAW 264.7 cells was employed to assess cellular antioxidant activity. Pretreatment with PITT significantly reduced intracellular reactive oxygen species (ROS) levels, enhanced the activities of endogenous antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase), and decreased malondialdehyde (MDA) levels. These results indicate that PITT exhibits notable antioxidant activity and may serve as a potential natural antioxidant source for further development. However, further studies are required to elucidate the underlying mechanisms.