In this study, we obtained and fractionated systematically the polysaccharides of Fructus mori fruit by the sequential use of water extraction, ethanol precipitation and ion-exchange chromatography. The sugar contents of FPA-1, FPA-2, FPA-4 and FPA-5 were estimated to be 75.70%, 67.15%, 87.78% and 91.63%, respectively. Monosaccharide composition analysis revealed that all the polysaccharides primarily contained Man, GlcA, GalA, Glc, Gal, Xyl, Ara and Fuc. Moreover, a small amount of Rha was detected in FPA-1, FPA-4 and FPA-5. The molecular weight distributions of FPA-1, FPA-2, FPA-4 and FPA-5 were 10.6-49.1 kDa, 22.9-122.7 kDa, 57.1-105.4 kDa and 14.8-19.6 kDa, respectively. According to the in vitro experiment, FPA-1 exhibited the highest activity on enhancing phagocytosis, promoting macrophage to secrete nitric oxide, tumour necrosis factor-α and reactive oxygen species.
Keywords: Fruit of Morus alba L.; Immunostimulation; Macrophages; Polysaccharides.
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