Study On Selective Adsorption Of Flavonoids On Fe₃O₄Nanoparticles

The composition of Chinese medicine, a natural product, is complex and its pharmacodynamics characteristics are regulated by the synergy of many compounds. Over one-third of drugs in clinical development so far directly come from the natural product, or from the derivatives, which are further developed from the active ingredients as a precurs, or from analogues,or from total synthetic products. In China, studies on chemical constituents of traditional Chinese medicine always begin with obtaining compound monomers through a variety of traditional means of separation and purification, then determine structures by spectroscopic and chemical means, finally track the biological activity of the monomers, and thus, the separation and purification of Chinese medicine active ingredients is particularly important. Currently, many scholars at home and abroad have launched a series of researches on traditional Chinese medicine, and developed a variety of effective separation and purification methods, and can be informed with relevant biological activity.However, the separation and purification technics also stay the level of coarse purification. The product after purification is a mixture with several or even dozens of compounds.The progress of the separation and purification of the pure monomer from the traditional Chinese medicine is still tedious, time-consuming,and costly. Therefore, the development of a rapid and simple method,which can be directly used to obtain pure monomers is significantly important.In this paper, iron oxide magnetic nanoparticles were used as adsorption carrier to absorb flavonoids from the root extractive of Scutellaria. After magnetic separating and desorpting, we separated and purificated two flavonoid compounds. The results showed that the selective adsorption between iron oxide nanoparticles andthe root extractive of Scutellaria is obvious, and the property of adsorption is related to its molecular structure. Compared with traditional purification methods, the most significant advantages of this method is high selectivity. By means of that, we can directly isolated flavonoid monomers from the extractive of Scutellaria, and the entire separation process saves time and effort, and operates simply. Therefore, the method of separation of the adsoption carrier and raw material liquid by an external magnetic field is really good.This study has mainly finished the following work:1. The magnetic Fe3O4nanoparticles were synthesized by coprecipitation method in this article. Several factors, including molar ratio of ferrous to ferric ions, total ferric concentration,, pH value, temperature of reaction, ammonia concentration, and pH value of the solution, stirring rate, adding rate of ammonia, were studied to investigate their influence on the formation of Fe3O4. The optimal reaction conditions were as follows, molar ratio of ferrous to ferric ions at1:2, total ferric concentration at0.9mol/L, pH value at9-10, temperature of reaction at65℃, stirring rate at800rpm, and adding rate of ammonia at10mL/min. Under the optimal condition, small sized and monodispersed Fe3O4nanoparticles could be obtained.2. Iron oxide magnetic nanoparticles were used as adsorption carrier to absorb flavonoids from the root extractive of Scutellaria. The results showed that the selective adsorption between iron oxide nanoparticles andthe root extractive of Scutellaria is obvious. We confirmed that the selective adsorption of nanoparticles on the flavonoid composition is caused by the carboxyl group on the benzene ring and adjacent hydroxyl via investigating the adsorption of benzene ring compounds.3. Benzoic acid and catechol were used as model compounds to study the effect of solvent, conentration, time, temprature and pH on the surface adsorption of the iron oxide magnetic nanoparticles, then we obtained the nearest adsorption conditions, and we also canvassed the influences of pH and ionic strength on the disadsorption, then obtaining the optimal conditions of disadsorption. Under the best conditions of adsorption and disadsorption,we separated and purificated two flavonoid compounds sucessfully.