Curcumin pyrazole blocks lipopolysaccharide-induced inflammation via suppression of JNK activation in RAW 264.7 macrophages

Background: Targeting inflammatory macrophages and their products is an effective method for controlling inflammation.The pyrazole analog of curcumin (curcumin pyrazole, PYR) has been reported to possess superior anti-inflammatory activity to curcumin (CUR).However, the role of PYR anti-inflammatory activity in macrophages has not yet been elucidated.Objective: To examine the anti-inflammatory effects of PYR and CUR in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages and determine the role of mitogen-activated protein kinases (MAPK) in their activity.Methods: Nitrite level was investigated by the Griess assay.The expression of inducible nitric oxide (NO) synthase, cyclooxygenase-2 (COX-2), and MAPK proteins were analyzed by western blot analysis.The pro-inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and interleukin-6 (IL-6) were measured by enzyme-linked immunosorbent assay.Results: LPS-induced NO secretion in RAW 264.7 macrophages was potently inhibited by PYR (IC 50 = 3.7 ± 0.16 μM), at a higher efficacy than CUR (IC 50 = 11.0 ± 0.59 μM).Treatment with identical concentrations of PYR and CUR demonstrated that PYR drastically inhibited iNOS and COX-2 expression, whereas CUR only blocked COX-2.PYR reduced the LPS-induced secretion of TNF-α to a greater extent than CUR and both similarly reduced IL-1β and IL-6 levels.Activation of c-Jun N-terminal kinase (JNK) MAPK was significantly decreased in LPS-activated RAW 264.7 macrophages upon PYR but not CUR treatment. Conclusion:PYR exhibited a more potent anti-inflammatory activity than CUR.This activity is partly mediated by PYR-depended inhibition of the JNK signaling pathway and underscores the utility of PYR as an anti-inflammatory agent in macrophages.