Curc-mPEG454, a PEGylated Curcumin Derivative, Improves Anti-inflammatory and Antioxidant Activities: a Comparative Study

We previously demonstrated that a PEGylated curcumin (Curc-mPEG454) significantly inhibited cyclooxygenase 2 (COX-2) expression and improved the progression of liver fibrosis. The current study systematically evaluates its anti-inflammatory and antioxidant activities in vitro in a comparative study with curcumin, aspirin, NS-398, and vitamin C. RAW264.7 murine macrophages were pretreated with Curc-mPEG454, curcumin, aspirin, NS-398, or vitamin C at the indicated concentration for 2 h; then, the cells were stimulated with 1 μg/mL lipopolysaccharide (LPS) for 24 h. The levels of pro-inflammatory cytokines and mediators, including IL-6, TNF-α, PGE2, NO, and GSH, and the activities of COX-2, SOD, and CAT, and the transcription factors involved in inflammation, such as NF-κB, c-Jun, and Nrf2, were measured. Curc-mPEG454 showed lower cytotoxicity (IC50 57.8 μM) when compared with that of curcumin (IC50 32.6 μM) and inhibited the release of the inflammatory cytokines IL-6, TNF-α, IL-1β, and MCP-1 in a concentration-dependent manner. At 16 μM, Curc-mPEG454 was most potent in the suppression of COX-2 expression at a transcriptional level rather than in the suppression of the catalytic activity of COX-2. Like curcumin, Curc-mPEG454 significantly reduced intracellular ROS production and enhanced the activities of SOD and CAT and the level of GSH to protect cells from LPS-induced oxidative injury. Further, its anti-inflammatory and antioxidation mechanisms are related to inhibition of NF-κB p65 nuclear translocation and c-Jun phosphorylation and to activation of Nrf2. Taken together, these findings indicate that PEGylation of curcumin not only improves its biological properties but also interferes with multiple targets involved in the inflammatory response. Curc-mPEG454 is a powerful and beneficial anti-inflammatory and antioxidant agent that merits further investigation. Graphical Abstract ᅟ.