A Sesquiterpenoid from Schizophyllum commune Protects C17.2 Neural Stem Cells Against Oxidative Stress Through Modulation of GPCR-Associated Signaling Pathways.

The chemical constituents and neuroprotective potential of Schizophyllum commune remain insufficiently characterized. Therefore, we isolated and identified five secondary metabolites (A-E) from S. commune, and investigated their neuroprotective activities and underlying mechanisms. Compound C showed the most significant protective effect against H2O2-induced cytotoxicity in C17.2 neural stem cells. Spectroscopy was used to structurally characterize the isolated compounds. Using RNA sequencing (RNA-seq), compound C was found to significantly modulate genes associated with G protein-coupled receptor (GPCR)-related signaling pathways and neuroactive ligand-receptor interactions. Differentially expressed genes, including Adora2a, S1pr1, Adm, Tbxa2r, and Grin3b, were validated using quantitative real-time PCR. They are associated with GPCR-related signaling and neurotransmission pathways, consistent with the RNA-seq data. As indicated by the functional enrichment analysis, compound C may regulate neuronal stress responses through GPCR-associated signaling networks. In the Western blot, compound C markedly attenuated H2O2-induced protein kinase A (PKA) C phosphorylation without altering total PKA C expression, suggesting that modulation of the cAMP/PKA signaling pathway may contribute to the neuroprotective effects of compound C. Collectively, compound C may exert neuroprotective effects against oxidative stress-induced neuronal injury, potentially through the modulation of GPCR-mediated PKA signaling. S. commune is a promising natural bioactive compound source for further development in neuroprotective research.