Filamentous fungi produce several beneficial secondary metabolites, including bioactive compounds, food additives, and biofuels. Trichoderma, which is a teleomorphic Hypocrea that falls under the taxonomic groups Ascomycota and Dikarya, is an extensively studied fungal genus. In an ongoing study that seeks to discover bioactive natural products, we investigated potential bioactive metabolites from the methanolic extract of cultured Trichoderma gamsii. Using liquid chromatography–mass spectrometry (LC–MS), one major compound was isolated and structurally identified as 6-pentyl-α-pyrone (6PP) based on nuclear magnetic resonance data and LC–MS analysis. To determine its antioxidant and anti-inflammatory activity, as well as the underlying mechanisms, we treated lipopolysaccharide (LPS)-stimulated Raw264.7 mouse macrophages with 6PP. We found that 6PP suppresses LPS-induced increase in the levels of nitric oxide, a mediator of oxidative stress and inflammation, and restores LPS-mediated depletion of total glutathione by stabilizing nuclear factor erythroid 2-related factor 2 (Nrf2), an antioxidative factor, and elevating heme oxygenase-1 levels. Furthermore, 6PP inhibited LPS-induced production of proinflammatory cytokines, which are, at least in part, regulated by heme oxygenase-1 (HO-1). 6PP suppressed proinflammatory responses by inhibiting the nuclear localization of nuclear factor kappa B (NF-κB), as well as by dephosphorylating the mitogen-activated protein kinases (MAPKs). These results indicate that 6PP can protect macrophages against oxidative stress and LPS-induced excessive inflammatory responses by activating the Nrf2/HO-1 pathway while inhibiting the proinflammatory, NF-κB, and MAPK pathways.

Botanical extracts are recognized in traditional medicine for their therapeutic potential and safety standards. Botanical extracts are viable and sustainable alternatives to synthetic drugs, being essential in drug discovery for various diseases. Senna septemtrionalis (Viv.) H.S. Irwin & Barneby is a medical plant traditionally used to treat inflammation. However, its antioxidant and anti-inflammatory properties and the molecular pathways activated in microglial cells require further investigation. Therefore, this study examines the antioxidant and anti-inflammatory properties of Senna septemtrionalis (Viv.) H.S. Irwin & Barneby methanol extracts (SMEs) in lipopolysaccharide (LPS)-stimulated mouse microglial cells. SMEs significantly inhibit LPS-induced nitric oxide (NO) and proinflammatory cytokine production, which are mediated through the dephosphorylation of mitogen-activated protein kinases and inhibition of nuclear factor kappa B (NF-κB) translocation into the nucleus. Additionally, SME treatment upregulated the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase (HO)-1, reducing oxidative stress, indicated by a decrease in reactive oxygen species and restoration of the total glutathione content in LPS-stimulated BV2 cells. The inhibitory effects of SMEs on inflammatory mediator production and NF-κB nuclear translocation were significantly reversed by Sn-protoporphyrin, a specific HO-1 inhibitor. These findings demonstrate that SME protects microglial cells by activating the Nrf2/HO-1 pathway and inhibiting NF-κB translocation.