Study On Lutein Microcapsules

Lutein is a kind of carotenoids. In humans, as in plants, lutein is believed to function in two important ways: first as a filter of high-energy blue light, and second as an antioxidant that quenches and scavenges photo induced reactive oxygen species (ROS). Lutein supplementation results in increased macular pigment and improved vision in patients with AMD and other ocular diseases. Lutein may also serve to protect skin from UV-induced damage and may help reduce the risk of cardiovascular disease.However, because of the presence of a long chain of conjugated carbon-carbon double bonds, lutein is susceptible to chemical changes when exposed to light and heat, thus it is important to improve its stability to maintain its biological activity. In this research, we prepared lutein microcapsules and use gelatin as its wall material. Microencapsulation is an effective method for oxidative stabilization of drugs. In this research, the stability of lutein was significantly improved because the wall acts as physical and permeability barrier for molecular oxygen diffusion. The research supplied one path for lutein to use in drug and food industry.Objective: (1) To Preliminary screening the microcapsule's preparation method; (2) To evaluated of the morphology of lutein microcapsules; (3) To establish the method to determine the lutein content in the microcapsule; (4) To establish the method for the delivery determination of lutein microcapsules in stimulated intestinal fluid and the stimulated gastric fluid; (5) To estimate the pharmacokinetics of the raw and lutein microcapsules in dogs.Methods: The research investigated the methods of single coacervation , complex coacervation and spray-drying to prepare lutein microcapsules. By using the average encapsulation rate and shape of microcapsule as control, the single factorial tests were carried out. And based on that, we optimize the prescription process by orthogonal test. The size and shape were examined by optical microscope and the outer topography was observed by scanning electron microscope.In the control of raw materials, the stability of lutein microcapsules was investigatedThe method for the delivery determination of lutein microcapsules in stimulated intestinal fluid and the stimulated gastric fluid was established,and the release characteristic was estimatedThe health hybrid male dogs were used as experiment subjects and lutein powder used as standard to estimate the pharmacokinetics of lutein microcapsules. After orally administered single dose of 3mg/kg body weight to dogs, blood sample was collected from the limbs vein at predetermined time intervals. The content of lutein in plasma was determined by reversed-phase HPLC method. The pharmacokinetics parameters were estimated by 3p87 program.Results: The preparation process of microcapsules was selected preliminarily and the simple coacervation of gelatin on the addition of 20%(w/v) sodium sulphate solution was used to prepare lutein microcapsule. The optimum method of that the ratio of coating material to lutein was 1.5:0.2, the temperature was 50℃, and the stirring speed was 400rpm. Glutaraldehyde was used to harden the microcapsules. The encapsulation rate of the lutein microcapsule was 80%, and the load efficiency was above 20%.After freeze drying , spherical or sphere-like vesicles with multiple red cores were observed under the optical microscope,and the diameter ranged from 20μm to 100μm, the mean diameter was 60.75±11.13μm . The outer apperence under the scanning electron microscope was round and smooth.The physical stability of lutein was significantly increased by encapsulation.The release speed of lutein microcapsules in stimulated gastric fluid was much lower than that in stimulated intestinal fluid, and the release exhibited the enteric and retarded property.Pharmacokinetics behavior of the raw lutein and microcapsules were conformed to one compartment model. The parameter of lutein raw was AUC0-168=2.145, t1/2=37.48h; And the microcapsules was AUC0-168=2.473, t1/2=55.76h. Pharmacokinetic characteristic of lutein microcapsules in dogs displayed a sustained-release of lutein, half life was extended, and the bioavailability was elevated.Conclusions: microcapsules prepared by simple coacervation and subsequent cross linking of gelatin represent promising carriers for drug delivery. The stability of lutein was significantly increased by encapsulation, and the release exhibited the enteric and retarded property. As the preparation for oral use, in vivo half life of lutein microcapsules was extended, and the bioavailability was elevated. The data can be useful for the futher study of lutein and microcapsules.