Biological Characteristics, Domesticated Cultivation Protocol, Antioxidant Activity, and Protective Effects against Cellular Oxidative Stress of an Underutilized Medicinal Mushroom: Fomitopsis palustris .

Brown-rot fungus is one of the important medicinal mushrooms, which include some species within the genus Fomitopsis . This study identified wild macrofungi collected from a broad-leaved tree in Liaoning Province as Fomitopsis palustris using both morphological and molecular methods. To elucidate the potential medicinal and economic value of F. palustris , we conducted single-factor and orthogonal tests to optimize its mycelium culture conditions. Subsequently, we completed liquid culture and domestic cultivation based on these findings. Furthermore, crude polysaccharides were extracted from the cultivated fruiting bodies of F. palustris and their antioxidant activity was evaluated using chemical methods and cell-based models. The results showed that the optimal culture conditions for F. palustris mycelium were glucose as the carbon source, yeast extract powder as the nitrogen source, pH 6.0, and a temperature of 35 °C. Moreover, temperature was found to have the most significant impact on mycelial growth. The liquid strains were fermented for 6 days and then inoculated into a cultivation substrate composed of broadleaf sawdust, resulting in mature fruiting bodies in approximately 60 days. The crude polysaccharides extracted from the cultivated fruiting bodies of F. palustris (FPPs) possess in vitro scavenging abilities against DPPH radicals and OH radicals, as well as a certain ferric-reducing antioxidant power. Additionally, FPPs effectively mitigated H 2 O 2 -induced oxidative stress in RAW264.7cells by enhancing the intracellular activity of antioxidant enzymes such as SOD and CAT, scavenging excess ROS, and reducing MDA levels. This study provides preliminarily evidence of the potential medicinal and economic value of F. palustris and offers initial data for the future development and utilization of this species.