Studies On Physicochemical Of Crystal Flavonoids By Polymorphism Of Puerarin

With the research and development of natural products, their active compounds, especially flavonoids had been the focus of drug raw material R&D. But it was reported that structure, solubility and spectrum of crystal flavonoids were different, which had baffled the application of drug, such as puerarin. Determination data of puerarin in recent years showed in disorder, so it had great effect on drug quality standard.With the help of modern instruments, there were three crystalline forms and one non-crystalline form from magnified pictures, infrared spectrum, DSC, TGA and X-ray powder diffraction; The melting point of puerarin ranged from 182 to 211 ℃; The solubility descended while size of crystal increased, which ranged from 3.29mg/ml to 3.66mg/ml in 8℃; Compared with normal solvents, crystal from super critical fluid extraction had the fewest residue solvents; best quality and shape; and only SCFE crystal IR spectrum was the most similar with the standard IR spectrum in Chinese Pharmacopoeia than other crystals.From the theory of hydrogen bond and dielectric constant, the solubility of puerarin in different solvents and mixed solvents had been explained. Final results showed the solubility of puerarin was related with dielectric requirement which was 35. Because of low viscidity and high solubility, 70% isopropanol and water had been selected as the solvent of puerarin injection rather than 50% 1,2-propandiol and water.