Preliminary Study On The Product Specifications Of Mulberry Medicinal Materials And The Structural Characteristics And Antioxidant Activity Of Mulberry Polysaccharides

Mori Fructus is the fruit of Morus alba L.and is one of the traditional Chinese medicinal materials.The Mori Fructus resources are plentiful in China and are distributed in most parts of the country.At present,the specifications and grades of Mori Fructus that circulated in the market are confusing and there is no clear standard for classification.In addition to the two specifications of selected goods and unitive goods,in some markets,there are green Mori Fructus and white Mori Fructus that do not meet the requirements of the “Chinese Pharmacopoeia”.In this paper,the commercial specifications and grades for Mori Fructus were established,and the extraction process,separation and purification,structural characteristics and antioxidant activity of polysaccharide from Mori Fructus were systematically studied,aiming to provide scientific basis for regulating and improving the quality of Mori Fructus and in-depth development of Mori Fructus medicinal materials.The main research contents are as follows:1.Study on the standard of commercial specifications and grades for Mori Fructus.According to the literature research,market research,origin research and the three principles of “Based on the Pharmacopoeia,market first,simple and practical”,selected the following indicators for reference indexes of the commercial specifications and grades standard for Mori Fructus: the size,the fullness,the colour and sweetness,etc.Mori Fructus medicinal material was divided into two specifications: selected specification and popular specification.The length of the selected goods was 1.5~2.0 cm and the diameter was 0.6~0.8 cm,the surface was dark purple.The surface of the popular goods was yellow-brown,brown-red or dark purple.2.Study on extraction process of polysaccharide from Mori Fructus.The extraction process of polysaccharide from Mori Fructus was studied by single factor and orthogonal test methods,the optimum extraction conditions were extraction temperature 100?,solid-liquid ratio 1:12,extraction duration 3 h and extraction three times,the polysaccharide yield under the optimized conditions was 16.87%.3.Study on the purification and composition analysis of polysaccharide from Mori Fructus.Mori Fructus was extracted with hot water,precipitated with alcohol,decolorizated with activated carbon,the free proteins were removed by Sevag method,then the crude polysaccharide MFP was obtained.The polysaccharide fraction MFPA-1 was purified from MFP by DEAE-cellulose column and Sephadex G-100 column chromatography.Its HPLC profile appear a symmetrical peak,indicating that the polysaccharide is homogeneous.The UV scan results showed that MFPA-1 does not contain proteins and nucleic acids.The monosaccharide was studied with chromatography method,MFPA-1 was composed of glucose,rhamnose,arabinose,mannose and galactose with a molar ratio of 93.4 : 1 : 1.1 : 1.8 : 2.7.The monosaccharide and glycuronic acid content of MFPA-1 was measured,the result showed that MFPA-1 contains monosaccharide about 80.9%,and glycuronic acid about 5.3%.4.Study on the physicochemical properties and structural analysis of polysaccharide MFPA-1 from Mori Fructus.The physicochemical properties and structural characteristics of polysaccharide MFPA-1 from Mori Fructus were studied by modern analytical methods such as GC,HPLC,UV,IR,periodic acid oxidation,Smith degradation and Congo red experiments.The results showed that MFPA-1 is a white solid.it could solute in water and not solute in organic solvents such as acetone and ethanol.There was no amino acid,protein and starch in MFPA-1.The molecular weight of MFPA-1 was 127.9 kDa.The main backbone of the polysaccharide MFPA-1 was mainly consisted of(1?2)-linked glucose with branches of(1?2)-linked mannose,(1?2)-linked rhamnose,(1?3)-linked arabinose and(1?3)-linked galactose.MFPA-1 was linked by pyranose bonds of ? and ? configuration,it had three helix molecular structures and had a characteristic absorption peak of carbohydrates.5.Study on the antioxidant activity of polysaccharides isolated from Mori Fructus.The antioxidant activity of crude polysaccharide MFP from Mori Frudtus was tested in vitro.The results showed that MFP has a certain antioxidant activity,its DPPH radical scavenging ability was strong.The clearance rate was 95.42% at a concentration of 0.9 mg/mL,which was close to that of the positive control Vc.The ·OH radical scavenging ability,reducing ability and total antioxidant capacity are relatively weak compared with Vc.In a certain concentration range,the antioxidant activity of MFP was positively correlated with its concentration.