Antioxidant and Cytotoxic Evaluation of Aqueous Extracts from Hymenochaetaceae Fungi Associated with Endemic Chilean Sclerophyll Forest Trees

In the search for safe and effective natural antioxidants, this study investigates the antioxidant and cytotoxic properties of aqueous extracts obtained from three fungi of the family <i>Hymenochaetaceae</i>: <i>Inonotus</i> sp., <i>Fulvifomes</i> sp., and <i>Phylloporia boldo</i>, all associated with endemic trees of the Chilean sclerophyll forest. Antioxidant capacity was assessed through DPPH, ABTS, and hydroxyl radical scavenging assays. <i>Fulvifomes</i> sp. exhibited the highest antioxidant activity across all methods, which was consistent with its elevated polyphenol content. <i>P. boldo</i>, on the other hand, had the highest protein concentration but comparatively lower antioxidant activity. Cytotoxicity was evaluated using the WST-1 assay in the RTgill-W1 salmonid cell line, revealing that <i>Inonotus</i> sp. displayed the lowest cytotoxicity at both tested concentrations, suggesting it may be suitable for bioactive applications in aquaculture. In contrast, <i>Fulvifomes</i> sp. and <i>P. boldo</i> showed significant cytotoxic effects at higher concentrations. These findings highlight the potential of <i>Inonotus</i> sp. as a natural antioxidant with low cytotoxicity and encourages further exploration of native forest fungi as sources of functional bioactive compounds for food, nutraceutical, or aquaculture applications.