| Bletilla striata (Bletilla striata(Thunb) Reichb. f), traditional Chinese herbal medicine, are considered to be high medicinal value. The virtue of Bletilla striata has been convergence bleeding, moisturizing, anti-aging skin, swelling of myogenic effect. The modern medicine has certified that Bletilla striata polysaccharide have some efficacy such as anti-tumor, hypoglycemic, anti-oxidation and promoting gastric digestion, etc. In addition, Bletilla striata polysaccharide is similar to gum Arabic with special viscosity characteristics and a low toxicity and safe polymers. It is a lot of potential development value. In the paper, the experiment was basied on Bletilla striata’s tuber as raw material and mianly researched the extraction process, separation and purification, physical and chemical properties and biological activities of Bletilla striata polysaccharide, which provides the theoretical foundation for the development and application of Bletilla striata polysaccharide as active ingredient in cosmetics.1. Bletilla striata polysaccharide was obtained by water extraction-alcohol precipitation, the experiment was on the basis of the water bath shaking table equipmentand optimized extractional conditions by response surface analysis. The optimal conditions were to be solid to liquid ratio 1:50 (g/mL), extraction temperature 80 ℃, extraction duration 4 h and the yield of the polysaccharide under above conditions could reach 29.84%. The optimal condition of alcohol precipitation process for the polysaccharide was shown below:the ethanol to concentrated solution volume ratio 4 (V/V), ethanol concentration 75%, alcohol precipitation time 2h.2. To study the effect on on the physicochemical characteristic of polysaccharides obtained from Bletilla striata by vacuum-drying and vacuum freeze-drying. The Bletilla striata polysaccharide was evaluated using HPSEC-MALLS, monosaccharide analysis, FT-IR spectroscopy and UV spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results showed that the polysaccharide derived from Bletilla striata was a neutral polysaccharide that is composed of glucose and mannose. The molar ratio of glucose to mannose, the number average molecular weight (Mn) and the computed average molecular weight (Mw) for Bletilla striata polysaccharide obtained by vacuum freeze-drying were 1:2.85,7.297×104 g/mol and 9.545×104 g/mol respectively. Whereas the molar ratio of glucose to mannose, Mn and Mw for Bletilla striata polysaccharide obtained by vacuum-drying were 1:2.81,1.218×105 g/mol and 1.472×105 g/mol respectively.3. To examine the antioxidant properties of Bletilla striata polysaccharide with different concentrations, the results indicated that when the concentration of the polysaccharide reached 10mg/mL, the scavenging rate on DPPH was 53.8%. The polysaccharide cleared to ·OH and its reducing power is small.In addition, when the concentration of the polysaccharide reached 10mg/mL, the inhibition effect of the polysaccharide on lipid axidation was 29.96%.Hygroscopicity and moisturizing performance in vitro of the polysaccharide were studied. Skin moisture test was evaluated by adding the polysaccharide to cosmetic cream formula. Under atmospheric condition of RH=43%, maximum hygroscopicity of the polysaccharide achieves 6.0%, and its moisturizing rate achieves 88.8%. Under atmospheric condition of RH=81%, maximum hygroscopicity of the polysaccharide reaches 99.0%, and its moisturizing rate reaches 105.5%. The hygroscopicity and moisturizing performance of the polysaccharide are greater than glycerin and hyaluronic acid. The moisture content of the test area daubed by cream containing the polysaccharide increased and it is significant that the moisture content of the test area daubed by cream containing 10%～15%the polysaccharide increased. |
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