Pharmaceutical Studies On APC

This paper summarizes the results of pharmaceutical studies on Angelica sinensis polysaccharide-iron complex (APC), mainly including the synthesis of APC, the physicochemical properties of APC, the optimization of the synthesis conditions of APC by orthogonal test, and the dissolution and bioavailability of iron(Ⅲ) in APC.Angelica sinensis polysaccharides (ASP) were extracted by means of using water as extracting solvent and ethanol as precipitator, and were purified with gel chromatography, and then APC was synthesized, under alkaline conditions, by dropping the solution of ferric chloride into the solution of ASP. APC is obtained as a red-brown powder, and APC is soluble in water, but is difficult to dissolve in organic solvents such as methanol, ethanol, ether and acetone. The melting of APC is higher than 300℃.The factors affecting the output and iron content of APC were studied, in order to optimize the synthesis conditions of APC. With the ratio of ASP to sodium citrate, the temperature of the water-bath, and the pH of the reacting solution as the influencing factors, and with the output and iron content of APC as the test indexes, the optimum synthesis conditions of APC were determined by using orthogonal test. From our studies the optimum synthesis conditions of APC are found to be that the ratio of ASP to sodium citrate is 4:1, the temperature of water-bath is about 70℃, and the pH of the reacting solution is about 8.The qualitatively identified reactions of APC and the content of iron(Ⅲ) in APC were studied. Based on the qualitatively identified reactions of ferric salts, the qualitatively identified reactions of APC were found out by comparing with ferric hydroxide. The iron content was determined with iodometry. The results of our studies indicate that the iron content in APC ranges from 10% to 40%, and the solubility of APC in water is closely related to the iron content. When the iron content is 20%~25%, APC has a better solubility in water.Some other physicochemical properties of APC were studied, so as to make a further understanding of the relationship between its properties and functions. The stability of APC under physiological pH conditions was judged by titrating APC with sodium hydroxide. The deoxidization of APC was tested with colorimetric analysis. The spectra characteristics and N, C, H content of the complex were examined by IR, NMR, and elemental analysis. Our studies indicate that the complex is stable at physiological pH from3 to 12, without precipitation and hydrolyzation, and at 37℃, iron(Ⅲ) in APC is almost completely reduced to iron(Ⅱ) by ascorbic acid in about 6 hours. The IR and NMR results show that the iron-containing core in the complex isβ-FeOOH core linked by hydroxy and oxy bridges. The elemental analysis shows that, due to the presence of iron core, the content of N, C, and H in APC are, respectively, lower than those in ASP.The dissolution and bioavailability of iron(Ⅲ) in APC were studied. The dissolution was tested with colorimetric analysis and the bioavailability was studied by comparing with ferrous sulfate. The results show that iron(Ⅲ) in the complex is released almost completely in 6 hours, and the bioavailability of iron(Ⅲ) in the complex is better than that of ferrous sulfate.From all the results of our studies described above, our conclusion is that APC consists of a colloidalβ-FeOOH core with ASP attached in some way to the surface of the core; and APC is stable, has a good deoxidization, dissolution and bioavailability of iron (Ⅲ), and so is promising to become a new iron supplementary.