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Nobiletin (NOB), a citrus polymethoxy flavonoid, has been reported to exhibit anti-inflammatory, anti-cancer, and anti-insulin resistance activities. Although the anti-inflammatory activity of NOB already reported, its involvement in lung protection has not been reported. Thus, this study aimed to investigate the anti-inflammatory response of NOB in lipopolysaccharide (LPS)-stimulated A549 cells and LPS-induced acute lung injury (ALI) in mice. The animals were pre-treated with NOB (5, 10, and 20 mg/kg) or DEX (5 mg/kg) at 12 and 1 h before intranasal instillation of LPS. The severity of pulmonary injury was evaluated 6 h after LPS administration. Results suggested that treatment with NOB dramatically attenuated lung histopathological changes, wet-to-dry (W/D) ratio, myeloperoxidase (MPO) activity, the numbers of inflammatory cells, and TNF-α, IL-6, and NO in BALF induced by LPS. Furthermore, NOB also significantly inhibited the expression of iNOS and the phosphorylation of NF-κBp65 and IκBα. In vitro, NOB inhibited NF-κB activation and TNF-α, IL-6 production in LPS-stimulated A549 cells. Taken together, these results indicated that NOB exhibited a protective effect on ALI, and the possible mechanism is involved in inhibiting NF-κB activation, subsequently inhibiting LPS-induced inflammatory response.

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Nobiletin (NOB), the major bioactive component of polymethoxyflavones in citrus fruits, has been reported possessing significant biological properties. The purpose of the present study was to investigate the protective role of NOB on lipopolysaccharide (LPS)-induced endotoxic shock in mice. We found pretreatment with NOB increases the survival rate of mice after endotoxin injection. The present study clearly demonstrates that pretreatment with NOB decreases the production of early pro-inflammatory cytokines TNF-α, IL-6, and late-phase mediator HMGB1 in serum and tissues of kidney, lung, and liver. The histopathological study indicates that NOB administration significantly attenuate tissues injury induced by LPS. Moreover, NOB suppresses the activity of nuclear factor-kappa B (NF-κB). These results suggest that NOB protects mice against LPS-induced endotoxic shock through inhibiting the production of TNF-α, IL-6, and HMGB1 and the activation of NF-κB, which elucidate that NOB may be a promising drug candidate for the treatment of septic shock.

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