Aim:The aim of this study was to investigate the effect of the squamosamide derivative FLZ (N-2-(4-hydroxy-phenyl)-ethyl-2-(2,5-dimethoxy-phenyl)-3-(3-methoxy-4-hydroxy-phenyl)-acrylamide) on lipopolysaccharide (LPS)-induced inflammatory mediator production and the underlying mechanism in RAW264.7 macrophages. Methods: RAW264.7 cells were preincubated with non-toxic concentrations of compound FLZ (1, 5, and 10 µmol/L) for 30 min and then stimulated with 10 μg/L LPS. The production of nitric oxide (NO), the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2), and the activation of nuclear factor kappa-B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways were examined. Results: FLZ significantly inhibited the LPS-induced production of NO, as well as the expression of iNOS and COX-2 at both the RNA and the protein levels in RAW264.7 cells. The LPS-induced increase in the DNA binding activity of NF-κB and activator protein 1 (AP-1), the nuclear translocation of NF-κB p65, the degradation of the inhibitory κBα protein (IκBα) and the phosphorylation of IκBα, IκB kinase (IKK) α/β, c-Jun NH 2 -terminal kinase (JNK) and p38 MAPKs were all suppressed by FLZ. However, the phosphorylation of extracellular signal-regulated kinase (ERK) was not affected. Further study revealed that FLZ inhibited the phosphorylation of transforming growth factor-β (TGF-β)-activated kinase 1 (TAK1), which is an upstream signaling molecule required for IKKα/β, JNK and p38 activation. Conclusion: FLZ inhibited the LPS-induced production of inflammatory mediators at least partly through the downregulation of the TAK-IKK and TAK-JNK/p38MAPK pathways.

Alzheimer's disease (AD) is the most common neurodegenerative disorder in which neuroinflammation plays an important role. FLZ is a novel synthetic derivative of natural squamosamide. Previous studies demonstrated that FLZ had neuroprotective effects on AD models and showed strong anti-inflammatory property in Parkinson's disease models. However, whether the neuroprotective effects of FLZ on AD are associated with its anti-inflammatory property is still not fully elucidated. In this study, we aimed to investigate the ability of FLZ in modulating inflammation. The results showed that FLZ significantly improved memory deficits and alleviated neuronal damage as well as neuronal loss in the hippocampus of mice intracerebroventricular injected with lipopolysaccharide (LPS). Mechanistic studies revealed that the neuroprotective effects of FLZ were due to the suppression of neuroinflammation induced by LPS, as indicated by inactivation of astrocytes and microglia, reduced production of tumor necrosis factor-α, interleukin-1β, and nitric oxide, as well as decreased expression of cyclooxygenase-2 and inducible nitric oxide synthase. The beneficial effects of FLZ on AD were further supported by the finding that FLZ attenuated β-amyloid production through inhibiting β-amyloid precursor protein cleaving enzyme 1 expression. These results suggested that anti-inflammatory agent could be useful for the treatment of AD.