Active Polysaccharides FCP5-A And FCAP1 From Fruit Of Cornus Officinalis: Isolation And Structural Characterization

Fruit of Cornus officinalis Sieb. et Zucc. has been used in Chinese traditional medicine for over two thousand of years for its effects of nourishing the liver and kidney. Polysaccharides, as essential components of Cornus officinalis, have attracted much attention. In this study, we investigated the isolation, purification, physicochemical properties, structure characterization and antioxidant activity of two polysaccharides from furit of Cornus officinalis, which were summarized as follows:1. Isolation, purification and physicochemical properties of polysaccharides from fruit of Cornus officinalisFruit of Cornus officinalis was extracted with water and a crude acidic water solubile polysaccharide was obtained. By column chromatography, an acidic polysaccharide FCP5-A was purified. The remaining debris of water extraction were extracted sequentially with alkali, fractionated with column chromatography and a neutral water solubile polysaccharide FCAP1 was gained. The physicochemical properties of FCP5-A and FCAP1 were determined using HPLC, GC, IR and spectrophotometer (Table 1).2. Structure characterization of FCP5-A By means of uronic acid reduction, methylation analysis and partial acid hydrolysis, GC-MS and ¹³C NMR analysis, the results indicated that FCP5-A was a branched polysaccharide rich in arabinose. The backbone was composed of repeated→4)GalA(1→2)Rha(1→, with side chains attached to O4 of some rhamnosyl residues. The side chains contained highly branched arabinan and short linear 1,3-linked galactan. It was concluded that FCP5-A was a new acidic polysaccharide of Cornus officinalis belonged to Rhamnogalacturonan I (RG-I).3. Structure characterization of FCAP1Based on methylation analysis, partial acid hydrolysis, enzyme hydrolysis, GC-MS and MALDI-TOF-MS analysis, FCAP1 was shown to be a highly branched polysaccharide with a backbone ofβ-1,4-linked-glucose. The backbone was partially substituted at O6 of glucosyl residues with Xyl_p-(1→, Gal_p-(1→2)-Xyl_p-(1→and Fuc_p-(1→2)-Gal_p-(1→2)-Xyl_p-(1→. The branches also contained -3)Ara(1-, -4)Glc(1-, -4)Man(1-, -4,6)Man(1-, Ara(1- and Gal(1-. It was concluded that FCAP1 was a xyloglucan of hemicellulosic polysaccharide.4. Antioxidant activities assay of FCP5-A and FCAP1Scavenging activity of superoxide radicals (O₂·^-) and hydroxyl radicals (·OH) were detected using self-oxidation of 1,2,3-phentriol assay and Fenton-reaction assay, respectively. Both FCP5-A and FCAP1 had the scavenging activity of O₂·^- and·OH. Compared with FCP5-A, FCAP1 had weaker scavenging power of O₂·^-, but stronger scavenging power of·OH. After removing the arabinan branches by partial acid hydrolysis, FCP5-A had evidently increased scavenging power of O₂·^- and·OH.