Chaga mushroom, Inonotus obliquus, was used as food and nutrient food and traditional herbs in Russia, China and Japan, with anti-inflammatory and anticancer activities. Chemical investigations of the fruiting bodies of Chaga were carried to uncover the bioactive metabolites. As a result, seven undescribed lanostane-type triterpenoids, namely inonotusols H-N, were isolated, and all lanostanoids remarkably inhibited NO production in lipopolysaccharide-stimulated BV-2 microglial cells. Of these, inonotusols I and L presented the most potent inhibitory effects on inducible nitric oxide synthase (iNOS) and NO production without any significant cytotoxicity. Molecular docking studies confirmed the capacity of inonotusols I and L to interact with iNOS protein. Structure-activity relationships were also discussed. These results indicated that the potential anti-inflammatory effects of inonotusols I and L in microglial BV-2 cells may be imparted through suppression of iNOS. These results may support the use of I. obliquus for food and medicinal application.
Keywords: Anti-neuroinflammatory activity; Hymenochaetaceae; Inonotus obliquus; Lanostane-type triterpenoids; Structure-activity relationships.
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