Edible O. fragrans flower ameliorates LPS-induced inflammatory responses through suppressing NF-κB and AP-1 pathways

Osmanthus fragrans (Thunb.) Lour. is one of the most common edible plants in China. Its flower (O. fragrans flower) is widely utilized as a food ingredient and traditional Chinese medicine for hundreds of years. In lipopolysaccharide (LPS)-activated macrophages, OFE suppressed the pro-inflammatory mediators (iNOS, MCP-1, IL-6 and IL-1β) at the transcriptional and translational levels, showing a potent anti-inflammatory effect. Mechanism study indicated that, OFE inhibited IκBα phosphorylation and prevented the nuclear translocation of p65, thereby inactivating nuclear factor-κB (NF-κB) signaling. Concurrently, OFE also suppressed AP-1 signaling through inhibiting the phosphorylation of c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and p38 MAPK. In endotoxemia mice, a single intraperitoneal administration of OFE significantly decreased serum IL-6 and MCP-1 levels. Our study demonstrates that O. fragrans flower may be the beneficial food for inflammatory diseases.