Studies On The Extraction Of Hypocrellin And Preparation Of Hypocrellin Liposomes

Hypocrellin, as a safe and efficient new photosensitizer, has aroused widespread attention and study. Hypocrellin is a lipophilic drug and vulnerable to the illumination, the raw materials mainly come from the wild stromata of Shiraia bambusicola, whose resources is quite limited. In this paper, high purity hypocrellin was extracted from Shiraia bambusicola fermentation products and liposomes was used as hypocrellin carrier, both to improve its water solubility and stability, and give full play to its good effect, which is obviously helpful to the development and utilization of hypocrellin.In this study, crystallization method was taken to get high purity hypocrellin, and hypocrellin liposomes was prepared by thin film-ultrasonic method with the preparation process optimized and its propertied examined. The main contents are as follows:(1) Compared with cooling crystallization and anti-solvent crystallization methods, evaporation crystallization method is more effective. According to the experimental study on the influence of solid-liquid ratio, evaporating temperature and agitation speed on the quality of hypocrellin products, the best experimental condition are: solid-liquid ratio is 1:30(m/V), static evaporate at 40℃. Hypocrellin average yield rate is 6.12% in this condition, its HPLC peak area ratio is 100.00%(2) Using petroleum ether extraction, D101 macroporous resin column chromatography and Sephadex micro-column centrifugation method for the determination of hypocrellin liposome encapsulation efficiency, the results show that the Sephadex micro-column centrifugation method is more suitable for detecting small sample. The experimental condition are: saturate micro-column with 1.5mL blank liposomes, add 0.5mL hypocrellin liposomes accurately and slowly, centrifugate at 2000r/min for 5min, then determine hypocrellin content and calculate encapsulation efficiency.(3) According to the single factor experiment and response surface analysis, the optimum conditions of the thin film-ultrasonic method for preparation of hypocrellin liposomes are: each 0.100g soybean lecithin join with 0.012g cholesterol, dissolved by chloroform solution containing 2.88mg hypocrellin, add 5.0mL PBS solution (pH 6.5) containing 0.01g Tween-80 to the drying lipid membrane, and then hydrate and rotate in 50℃water bath for 67min, ultrasonic for 20min in water bath, reserve at 4℃and protecte from light. The average liposome encapsulation efficiency is 90.59%, the drug loading is 2.61%. The hypocrellin liposome Zeta potential is -34±8mV (n=3), the average particle diameter is 261.4nm. Hypocrellin liposome is oval-shaped under transmission electron microscopic observation. Liposomes stored in 4℃and protected from ligh was good in stability in a month, experiments showed that the liposomes significantly contributes to the improvement of hypocrellin in an aqueous system for its fluorescence intensity and light stability.