Proliferatins suppress lipopolysaccharide-induced inflammation via inhibition of the NF-κB and MAPK signaling pathways

Three previously undescribed polyketides [proliferatin A-C (1–3)] with anti-inflammatory activity were isolated from Fusarium proliferatum. 1–3 attenuated the production of inflammatory signal messengers including nitric oxide (NO), reactive oxygen species, proinflammatory cytokines interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β), as well as the related proteins nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-induced RAW264.7 macrophages. Transcriptome analyses based on RNA-seq indicated the potential anti-inflammatory mechanism of 1–3 involved in the nuclear factor kappa-B (NF-κB) and mitogen activated protein kinases (MAPKs) signaling pathways. Experimental evaluation of the protein levels revealed that 1–3 can inhibit the phosphorylation of IκB kinase (IKK), the degradation of NF-κB Inhibitor-α (IκBα), the phosphorylation of nuclear factor-κB (NF-κB) and can reduce NF-κB transportation to the nucleus. Interestingly, 1–3 decreased the phosphorylation of MAPKs including p-p38, p-ERK, and p-JNK. Molecular docking models suggest that binding of 1–3 to TLR4-MD-2 complex may lead to inhibition of NF-κB and MAPK signaling pathways, which was confirmed in vitro by surface plasmon resonance (SPR) assays. 1–3 can thus constitute potential therapeutic candidates for the treatment of inflammation-associated diseases.