| Aralia chinensis L., which belongs to Araliaceae, Aralia, was widely distributed in the most areas of China. It has been used as Chinese herbal medicine as well as an edible food for many years, its buds and leaves rich in sugar, protein, amino acid, vitamin, crude fiber and carotene nutrients, was high-grade edible wild herbs; its root bark and stem bark can be used as medicine, which were effective on analgesia, anti-inflammatory, expel dampness and promote blood circulation. In this topic, the extraction technology, physicochemical properties and antioxidant activity of Aralia chinensis stem-bark polysaccharides(ACSP) were studied,which provided a theoretical basis for the study on the structure of ACSP and comprehensive development. The main results were as follows:1. The optimum extraction conditions of hot water extraction for ACSPHWE by using response surface analysis were determined as follows: ratio of water to material was 33 mL/g,extraction temperature was 80 ℃, extraction time was 3.1 h, under optimal conditions, the verified yield of ACSPHWE was 8.692 ? 0.12 %, which was in agreement with the predicted value 8.678 %, showed that the model generated was feasible to optimize the hot water extraction process of ACSPHWE;2. The optimum extraction conditions of ultrasonic-assisted extraction for ACSPUAE by using response surface analysis were determined as follows: ratio of water to material was 33mL/g, extraction temperature was 71 ℃, ultrasonic power was 124 W, extraction time was 93 min, under optimal conditions, the verified yield of ACSPUAE was 12.871 ? 0.11 %, which was in agreement with the predicted value 12.897 %, showed that the model generated was feasible to optimize the ultrasonic-assisted extraction process of ACSPUAE;3. Compared with the hot water extraction, ultrasonic assisted extraction method reduced the optimal extraction temperature, decreased the optimal extraction time, and significantly increased the yield of polysaccharides, which illustrated that in the extraction process of ACSP, taking the yield of polysaccharide as evaluation index, ultrasonic assisted extraction method was better than the hot water extraction;4. After protein and dialysis treatment in ACSP, we got ACSP-1, the solubility experiment of ACSP-1 showed that ACSP-1 can dissolve in water, freely soluble in hot water,insoluble in ethanol, ethyl ether, acetone, chloroform and butanol; iodine iodide kalium detection showed that ACSP-1 did not contain starch polysaccharide, fehling reagentdetection showed that ACSP-1 didn’t have nature of reducing sugar, ferric chloride test showed that ACSP-1 did not contain polyphenolic compounds, biuret method detection showed that ACSP-1 did not contain protein polysaccharide; UV scan results showed that ACSP-1 did not contain nucleic acids and proteins; FT-IR analysis implied that ACSP-1possessed typical absorption peaks of polysaccharides(3415.67cm-1、2926.00 cm-1、1647.21cm-1、1419.62 cm-1、1024.90 cm-1);5. The results of size exclusion chromatography with laser light scattering method(SEC-LLS) showed that ACSP-1 had the uniformity, its weight-average molecular weight(Mw) was 1.328×106 g/mol, number-average molecular weight(Mn) was 4.463×105 g/mol,molecular weight distribution index(Mw/Mn) was 2.976; gas chromatography mass spectrometry(GC-MS) analysis showed that monosaccharide composition of ACSP-1 were D-arabinose, D-glucose and D-galactose, the molar ratio was 1: 19.21: 4.01;6. The results of antioxidant activities of ACSP and ASCP-1 in vitro showed that the scavenging activity of ACSP and ASCP-1 on DPPH radical, hydroxyl radical, superoxide radical and reducing power increased gradually with the increase of polysaccharides concentration, and free radicals scavenging ability of ACSP-1 higher than ACSP, indicated that the purification of ACSP can enhance its antioxidant ability in a certain extent. |
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