Mechanism of Action and Anti-Inflammatory Activity of Pestalotioquinol A, a Fungus-Derived Cytoprotective Compound

Pestalotioquinol A (pesA) is a novel cytoprotective natural compound previously discovered among <i>Pestalotiopsis microspora</i> metabolites. PesA protects PC12 cells against cell death induced by a peroxynitrite donor, a reactive nitrogen species (RNS). In this study, we analyzed the mechanism of action of pesA and aimed to identify its target proteins. We revealed that the cytoprotective activity of pesA was specific to RNS, such as peroxynitrite and nitric oxide. A cellular thermal shift assay (CETSA) revealed elongation factor 1-α1 (EF1α1) as a potential pesA-binding protein. Cilostazol targeting EF1α1 displayed cytoprotective activity similar to pesA. EF1α1 knockdown increased peroxynitrite sensitivity and reduced the protective activity of pesA, suggesting that EF1α1 serves as a potential target. As RNSs are linked to inflammation, we examined the anti-inflammatory activity of pesA. PesA inhibited lipopolysaccharide-stimulated proinflammatory cytokine production in RAW264.7 cells. In an inflammatory bowel disease model mice, pesA significantly suppressed colon shortening and ameliorated total histopathological scores. PesA could help elucidate RNS-related events and serve as a lead compound for developing anti-inflammatory agents.