| The stomach is an alimentary tract, which delivers gastric contents to the intestines by incessant peristalsis. Hence, drugs can't be standed in the stomach, which leads to lack of the treatment effect.Therefore, there is of great significance on developing adjuvants of gastric retention agents for extending drug residence time in the stomach and improving clinical curative effects. The combination of medicines and adjuvants is a sophisticated application of traditional Chinese medicine. Bletilla striata polysaccharides gums (BSPG) is the active ingredients of Bletilla striata for hemostasis and promoting granulation, which is characteristic of flotage, adherency, swell and biocompatibility. It is an ideal biological carrier material for medicine in the stomach for the combination of medicines and adjuvants. Nowadays, BSPG as an adjuvant of gastric retention agents is expecting for further research.PurposeHence, the paper is thoroughly studying on the optimization for infrared assisted extraction of BSPG by response surface methodology, preparation the porous gum-bletilla, characterization of microstructure, physical and chemical properties, analysis of structure, the antioxidant activities of the purified gum-bletilla, as well as the preliminary evaluation on the factors of gastric retention. Moreover, BSPG, as the unification of drug and adjuvant as well as the functional auxiliary material of the intragastric floating-bioadhesive drug-delivery systems, whose mechanism and the scientific intension will be illustrated to develop a kind of an unification of drug and adjuvant, which has the synergic action of drug function and auxiliary material, embroad Bletilla striata's application sphere and promote the development of new pharmaceutical excipients and new dosage forms. Methods1.On the basis of the single-factor experiment, the software Design Expert (Trial Version 8.0.6.1, Stat-Ease Inc., Minneapolis, MN, USA) was employed for experimental design, data analysis and model building. The crude polysaccharides were obtained using infrared-assisted extraction (IRAE). A three-level, three-factor BBD was employed in this optimization study to determine the best combination of extraction variables for BSP extraction.2.Under the optimization for infrared assisted extraction conditions, using the alcohol precipitation technology and BSPG extracts were graded settlement, examines the optimal concentration of alcohol precipitation; The porous BSPG was made by freeze drying method and the physicochemical properties, texture analysis and the Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) were all employed to study the characterization of porous BSPG.3.BSP was further purified using DEAE-52 chromatography, and purified BSP was studied on radical scavenging activity against superoxide anion radicals, DPPH and hydroxyl radicals and the ability of chelate metal ions, such as Fe2+4.The porous BSPG was used as medicinal material to prepare the tablets, gastric retention performance was evaluated. The functional materials of the feasibility was studied, laying a sound foundation for the development of the application of BSPG.Results1.The optimum extraction conditions were slightly adjusted for practical application as follows:extraction temperature,75 ?; extraction time,2.5 h; and solids:water ratio,53 ml/g. Under these conditions, the experimental BSP yield was 43.95±0.26% and the relative error between the predicted value and the predicted value was 0.27%, which was consistent with the predicted yield; this result indicated that our model is accurate.2.The percentage of BSPG40, BSPG60 and BSPG80 are 83.25%,12.16%,4.49%. The content of total polysaccharide of BSPG, BSPG40, BSPG60, BSPG80 are 64.15%?69.33%?57.64%?42.83%, respectively.Each freeze dried sample properties and solution properties of texture analysis, show that different alcohol concentration of the sample and the performance exist certain correlation, such as the impact of its hardness, porosity and gel strength. In addition the micro-structure of BSPG was characterized, and tertiary structural analyses indicated that BSP had a triple-helical conformation. Fourier transform infrared spectroscopy characterization of BSP revealed typical absorption peaks.3.The in vitro antioxidant activity of the purified fraction demonstrated that BSPG has potential for use as a natural antioxidant.4.Porous BSPG has a porous internal structure and the porosity could reach 75?98%. It was founded porous BSPG has the ability of floating, the high water absorption and expansion excellent performance and natural, non-toxic, stable property, good biocompatibility, with fast floating, floating a long time performance, which show porous BSPG can be used as4.functional materials for gastric retention preparation.Conclusions1. The optimization of Infrared-assisted extraction of BSPG is stable and reliable, a high level of polysaccharides with fewer impurities was obtained,which indicated that optimized processes were suitable for industrial production of BSPG.2. The total polysaccharide from Bletilla striata was a neutral hydrophilic polysaccharide with a three-stage helical structure and the infrared characteristic peak datas, as well as the good properties, gelling behavior and texture characteristics.3. The purified BSP exhibited radical scavenging activity and has potential for use as a natural antioxidant.4. Porous BSPG can be an excellent material for gastric retention preparation and it is of great significance for the development and application of gastric retention preparation. |
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