Influence of Different Extraction and Purification Methods on Astragalus Polysaccharides and Pharmacological Evaluation

Objective To clarify the influence on component and pharmacological action of Astragalus polysaccharides(APS) as complementary therapeutic agents prepared by different extraction and purification techniques.Methods Components of APS prepared by different extraction and purification techniques were analyzed,and these APS were used for synergy and attenuation of chemotherapy,radiotherapy treatment with H22 liver cancer and Lewis lung cancer of tumor-bearing mice,and also used for the regulation of immune function to immunosuppression mice.Results Experimental data were analyzed by means of statistical method to get pharmaco-result:A3(extracted by microwave assistance and purified by membrane separation)>A4(extracted by refluxing and purified by membrane separation)>A1(extracted by refluxing and no purification)≈A2(extracted by microwave assistance and no purification).There were no significant differences on pharmacodynamic action between A1 and A2.However,compared with A1 and A2,it was worth noting that A3 and A4 exhibited good pharmacodynamic action.Then A3-in and A4-in,the samples in dialyzer after dialysis,were separated and purified to get homogeneous APS,which were the principal constituents of APS in dialyzer,with the molecular weight(Mw) of 7669 and 14142 determined by HPGPC,respectively.The average Mw of APS outside of the dialyzer,A3-out was 3102 and A4-out 3256,which were the main compositions of A3 and A4,accounted for 79.63% and 53.92%,respectively.Conclusion APS with Mw about 5000 Da exhibit better antitumor effect and immunological activity.Refluxing,microwave assistance extractions,and membrane enrichment techniques bring different cases on Mw distribution,components and pharmacodynamic action,and obviously exhibit relationship among component,Mw distribution,and pharmacological action.

Research status and prospects of melt refining and purification technology of magnesium alloys

Refining and purification is a significant way to obtain pure and high-quality magnesium alloy melts.This paper summarizes the flux refining methods and non-flux purification methods(blowing purification,filtration purification,electromagnetic purification and ultrasonic purification).It also introduces the composite refining technologies that have been widely researched and applied in recent years,including low-voltage pulse electromagnetic technology,ultrasonic argon purification,self-purification technology and non-flux continuous purification technology.Among them,the non-flux continuous purification technology integrates a variety of purification methods,which can produce high-quality magnesium alloy continuously and steadily,realize environmental protection production,and achieve remarkable technical and economic benefits.

Methods for cleaning turbid nematode suspensions collected from different land-use types and soil types

Soil nematodes are useful ecological indicators and can be extracted from soil by a variety of techniques.Because the extracted nematode samples(suspensions)can be quite turbid(i.e.,they contain soil particles and organic particles in addition to nematodes),quantitative and taxonomic analyses of the nematodes by microscopy can be difficult.In this study,the following three methods for cleaning turbid suspensions obtained from Baermann funnels were assessed:repeated centrifugation at 692.5´g for 1 min,repeated settling at low-temperature(4°C)for 24 h,and a combination of low-temperature settling and centrifugation.Nematodes were extracted with Baermann funnels from soil samples collected from four land-use types(since land-use type can affect the turbidity of nematode suspensions),and the resulting suspensions were cleaned by the three methods before nematode abundance was assessed.As a control,samples(i.e.,suspensions)were simply diluted with water,and nematodes were counted in the entire volume.The results showed that,within each land-use type,nematode abundance did not significantly differ between the control and the three cleaning methods.Averaged across all land-use types,however,the nematode recovery rate was slightly higher with repeated centrifugation than with the other two cleaning methods.Therefore,the proposed methods are sound for cleaning turbid nematode suspensions,and repeated centrifugation is the most efficient method.