A new benzoquinone and a new benzofuran from the edible mushroom Neolentinus lepideus and their inhibitory activity in NO production inhibition assay

The fruiting bodies or mycelia of mushrooms have been used as food and food-flavoring material for centuries due to their nutritional and medicinal value and the diversity of their bioactive components. The present research is the first to investigate the bioactive secondary metabolites from the solid culture of the edible mushroom Neolentinus lepideus. Two new secondary metabolites, 5-methoxyisobenzofuran-4,7(1H,3H)-dione (1) and 1,3-dihydroisobenzofuran-4,6-diol (2), as well as seven known compounds including one benzoquinone derivative (3) and six cinnamic acid derivatives (4–9) were obtained. Their structures were established by means of spectroscopic methods, including 1D and 2D NMR. The bioactivity on the nitric oxide production in lipopolysaccharide-induced macrophages was evaluated for all metabolites (1–9) isolated. Compound 1 showed strong NO inhibitory activity with the IC50 value of 6.2 μM. Compound 2 displayed moderate NO inhibitory activity with the IC50 value of 88.8 μM. In the DPPH scavenging assay, compound 2 displayed antioxidant activity with IC50 of 68.6 μM. The discovery of new NO production inhibitors from N. lepideus expands its usage as a functional food.