Bound polyphenols from insoluble dietary fiber of navel orange peel alleviates cellular inflammation by inhibiting LPS-induced NF-κB/JAK-STAT pathway in RAW264.7 macrophages

In this study, we explored the anti-inflammatory effects of bound polyphenols derived from the insoluble dietary fiber of navel orange peel (BPP) on LPS-induced RAW264.7 macrophages, and investigated the underlying molecular mechanisms. The experimental findings revealed that BPP effectively suppressed COX-2 and iNOS protein expression, and concurrently decreased intracellular ROS production and NO release. RNA sequencing identified 1,894 differentially expressed genes between the model and BPP groups, with 1,009 genes upregulated and 885 downregulated. Notably, the NF-κB and JAK-STAT pathways were among the 20 most significantly altered signaling pathways, as determined by KEGG analysis. Western blot analysis further showed that BPP significantly inhibited the phosphorylation of key proteins in the MAPKs (ERK, JNK, p38), NF-κB (p65, IκBα), and JAK-STAT (JAK1, STAT3) pathways. Additionally, the use of p65 and STAT3 activators markedly elevated NO and ROS levels, whereas BPP treatment effectively reduced them. These findings suggest that BPP may attenuate LPS-induced inflammatory responses through the NF-κB and JAK-STAT pathways, highlighting its potential as a natural anti-inflammatory agent and its implications for functional food applications.