Viburnum pichinchense methanol extract exerts anti-inflammatory effects via targeting the NF-κB and caspase-11 non-canonical inflammasome pathways in macrophages

Ethnopharmacological relevance: Viburnum pichinchense Benth. Mainly found in Ecuador and Colombia has been ethnopharmacologically utilized as a remedy for various female disorders with kidney inflammation and uterine relaxant. Aim of the study: The pharmacological activity of Viburnum pichinchense has never been studied, therefore, this study explored anti-inflammatory activity of Viburnum pichinchense methanol extract (Vp-ME). Materials and methods: Anti-inflammatory activities of Vp-ME were evaluated in lipopolysaccharide (LPS)-stimulated RAW264.7 cells and HCl/EtOH-induced gastritis mice by MTT assay, nitric oxide (NO) production assay, semi-quantitative reverse-transcriptase-polymerase chain reaction (RT-PCR), luciferase reporter assay, Western blotting, and enzyme-linked immunosorbent assays (ELISA). Anti-inflammatory compounds in Vp-ME were identified by high performance liquid chromatography (HPLC). Results: Vp-ME inhibited NO production in RAW264.7 cells stimulated with pam3CSK4, poly I:C or LPS and in LPS-stimulated peritoneal macrophages without cytotoxicity and downregulated mRNA expression of inflammatory enzymes, inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) and pro-inflammatory cytokines, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-6. The anti-inflammatory activity was accomplished by inhibiting nuclear factor-kappa B (NF-κB) transcriptional activation, upstream signaling molecules in the NF-κB pathway, and caspase-11 non-canonical inflammasome in RAW264.7 cells. Moreover, Vp-ME exhibited in vivo anti-inflammatory activity by ameliorating gastritis symptoms, inhibiting iNOS and IL-6 mRNA expression and IκBα activation in mice. HPLC analysis identified resveratrol, quercetin, luteolin, and kaempferol as the anti-inflammatory components in Vp-ME. Conclusion: This study demonstrated Vp-ME has the anti-inflammatory activity via targeting NF-κB and caspase-11 non-canonical inflammasome pathways in macrophage-mediated inflammatory responses, suggesting Vp-ME could be developed as anti-inflammatory ethnopharmacological remedies to prevent and treat inflammatory diseases.