Abstract: Objective To explore the anti-inflammatory mechanism of Fructus Gardenia extract by which viral pneumonia caused by influenza A (H1N1) virus (FM1) is inhibited in mice.Methods In vitro experiments: the effect of Fructus Gardenia extract of different concentrations on the secretion of NO was studied with mouse macrophage RAW 267.4 induced by lipopolysaccharide (LPS). The RAW 267.4 cells were stimulated by LPS of two concentrations for 24 hours and then by Fructus Gardeniae extract of corresponding concentrations. The content of NO in the cell supernatant was detected after 24 hours. In vivo experiments: Except for the normal group, the ICR mouse pneumonia model infected with influenza A (H1N1) virus (FM1) was used in all the other groups. After four days of continuous administration, blood was collected from the eyeball by centrifugation for flow cytometry detection of serum inflammatory factors. After dissection, lung tissue was taken for pathological section and lung lesions were observed. Results In vitro experiments showed that the 5, 2.5 and 1.25 mg/mL dosage groups of Fructus Gardeniae extract could effectively reduce NO content, and there was significant difference compared with the LPS control group (P< 0.01). In vivo experiments indicated that the high, medium and low dose groups of Fructus Gardeniae extract could reduce the contents of inflammatory factors interleukin -6 (IL-6), tumor necrosis factor α (TNF-α) and monocyte chemoattractant protein -1 (MCP-1) to different extents compared with the model group. The pathological examination of mouse lung tissue showed that compared with the model group, lung lesions were significantly improved in high and medium dose groups of Fructus Gardeniae extract.Conclusion Fructus Gardenia extract not only has a good anti-inflammatory effect in vitro, but also effectively inhibits mouse viral pneumonia caused by influenza A (H1N1) virus (FM1).

Key words: Fructus Gardenia extract, influenza A virus, lipopolysaccharide, inflammatory factors, mouse