Ethanolic extract and water-soluble polysaccharide from Chaenomeles speciosa fruit modulate lipopolysaccharide-induced nitric oxide production in RAW264.7 macrophage cells

摘要

Ethnopharmacological relevance: Chaenomeles speciosa fruits have been widely used in traditional Chinese medicine for treatment of diseases related to inflammatory reaction. This study aims to identify anti-inflammatory and immunomodulatory components of Chaenomeles speciosa fruit and unravel their potential mechanisms. Materials and methods: Ethanolic extract and its n-hexane, chloroform, ethyl acetate and n-butanol fractions, as well as water-soluble polysaccharide, were prepared from dry fruits of Chaenomeles speciosa. The mouse macrophage-like RAW264.7 cells were induced by lipopolysaccharide (LPS) and used as an inflammatory cell model. Production of nitric oxide in the cells was determined by the Griess assay, and cell viability was tested by the MTT method. Cellular apoptosis was evaluated by fluorescence-activated cell sorting. Relative quantification of inflammation-related genes was analyzed by real-time PCR. Results: LPS-induced production of nitric oxide in RAW264.7 cells was significantly inhibited by the ethyl acetate fraction (EAF) at 200-800 μg/ml, while Chaenomeles speciosa polysaccharide (CPS) promoted nitric oxide production at 250-750 μg/ml either alone or in an additive fashion with LPS. Both EAF and CPS did not provoke noticeable cytotoxicity and apoptosis at the above effective concentrations. EAF significantly reduced LPS-induced upshift of iNOS mRNA level but showed no significant effect on the induction of IFN-γ and G-CSF, while CPS reduced the gene induction of TNF-α, IFN-γ and G-CSF by LPS. Conclusions: EAF was able to inhibit nitric oxide production by reducing LPS-induced upshift of iNOS mRNA level. CPS was an activator of nitric oxide production through cytokines such as TNF-α, IFN-γ and G-CSF. These results demonstrate the therapeutic effects of both ethanolic and aqueous extracts of Chaenomeles speciosa fruit, a traditional edible medicine used in health maintenance and disease treatment.