| Dendrobium huoshanense C. Z. Tang et S. J. Cheng (Orchidaceous) is a perennial herbal plant and mainly distribute in Huoshan county, Anhui province of China. D. huoshanense is one of the earliest recorded medicinal plants in China, and possesses prominent medicinal value and enormous market demand. Recent research indicates that polysaccharides are one of major active ingredients of D. huoshanense and possesses a variety of bioactivities, including antioxidation, antitumour, immunity improvement and anticataract. In this paper, DHP-W2 was successfully isolated from D. huoshanense, and its structure features and anti-glycated activity were investigated respectively.Comparison between removal rate of protein and loss rate of polysaccharide in different concentrations of TCA indicated that 1.5% TCA was most appropriately used to remove protein.The crude polysaccharide of D. huoshanense was fractionated by DEAE-cellulose anion-exchange and gel filtration chromatography of Sephacryl S-200, giving one pure fraction DHP-W2. Its molecular weight was determined to be 7.3×104 by high-performance gel-permeation chromatography. The infrared spectra analysis revealed that DHP-W2 was a typical polysaccharide and the ultraviolet analysis indicated that DHP-W2 did not contain proteins and nucleic acids. DHP-W2 was composed of glucose, xylose and galactose in the ratio of 1.1 : 1.0 : 0.5, along with trace of galacturonic acid. Structural features of DHP-W2 were elucidated by methylation analysis and NMR spectroscopy. The results indicated that the backbone of DHP-W2 consisted of 1,6-linked and 1,4-linkedβ-D-glucose with branches at O-4/6. The branches consisted of 1,4-linkedα-D-xylose, 1,2,4-linkedα-D-xylose, 1-linkedα-D-xylose,α-D-galactose, andα-D-galacturonic acid. Preliminary pharmaceutical experiments showed that the DHP-W2 possessed anti-glycated activity. |
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