Crocin attenuates lipopolysacchride-induced acute lung injury in mice

Crocin, a representative of carotenoid compounds, exerts a spectrum of activities including radical scavenger, anti-microbial and anti-inflammatory properties. To investigate the protective effect of crocin on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice. ALI was induced in mice by intratracheal instillation of LPS (1 mg/kg). The mice received intragastric injection of crocin (50 mg/kg) 1 h before LPS administration. Pulmonary histological changes were evaluated by hematoxylineosin stain and lung wet/dry weight ratios were observed. Concentrations of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and nitric oxide (NO), and myeloperoxidase (MPO) activity were measured by enzymelinked immunosorbent assay. Expression of inducible nitric oxide synthase (iNOS) in lung tissues was determined by Western blot analysis. Crocin pretreatment significantly alleviated the severity of lung injury and inhibited the production of TNF-α and IL-1β in mice with ALI. After LPS administration, the lung wet/dry weight ratios, as an index of lung edema, and MPO activity were also markedly reduced by crocin pretreatment. Crocin pretreatment also reduced the concentrations of NO in lung tissues. Furthermore, the expression of iNOS was significantly suppressed by crocin pretreatment. Croncin potently protected against LPS-induced ALI and the protective effects of crocin may attribute partly to the suppression of iNOS expression.