Study On Puerarin Nanocrystalline Self-stabilizied Pickering Emulsion

Most of the active components from the traditional Chinese herbs are insoluble in water,which leads to a poor bioavailability and limits their clinical use.So how to improve their water solubility and bioavailability has been a great challenge for chinese medicine pharmaceutics.The nanocrystal self-stabilized Pickering emulsions(NSSPE),one kind of emulsions using nanocrystals of insoluble ingredient instead of surfactants or solid particles as stabilizers,has been created by our group firstly,which could improve the oral bioavailability of insoluble ingredients,increase the safety and stability of preparations.In this study,puerarin nanocrystalline self-stabilizied Pickering emulsion(Pu-NSSPE)was fabricated and charactered which used puerarin as nanocrystals and Rhizoma Chanxiong oil as main oil phase.The preparation technology was optimized.The stability and microstructures of Pu-NSSPE are investigated.The oral bioavailability of Pu-NSSPE in rats was studied.The specific research contents and results are as follows:(1)Study on preparation technology of Pu-NSSPEPu-NSSPE was developed using a high pressure homogenization method.The influences of drug addition sequence,property and construction of oil phase,drug concentration,oil/water ratio,homogenization pressure and pH of water phase on the formation and stability of Pu-NSSPE were investigated.On this base,Box-Behnken design was used to optimize the preparation technology with cream index,change of droplet size and drug concentration in emulsion after storage of 1 month as index.The optimized preparation process was as folloes: 350 mg puerarin was dispersed in 7 mL mixed oil which consisted of Rhizoma Chanxiong oil and Labrafil M 1944 CS(9: 1,v /v).Then 63 mL water was added and homogenized by high-speed homogenizer at19000 rpm for 2 min.The resultant coarse emulsions were then homogenized at 80 Mpa for 3 min.(2)Stability and structural characterization of Pu-NSSPEThe stability of optimized Pu-NSSPE within 6 months storage at 4 ?C,25 ?C and40 ?C was evaluated and the structure sof Pu-NSSPE were studied by SEM,CLSM and FIM.The in vitro drug realease was also investigated using dialysis method.The fresh Pu-NSSPE was milky.The size of emulsion droplet was 12.39 ? 0.91 μm,the drug content was 4.49 ? 0.21 mg·mL-1 and zeta potential was-47.73 ? 2.21 mV.The appearance,size of emulsion droplet,drug content and zeta potential of optimized Pu-NSSPE were not changed significantly after storage for 6 months at 4 ?C,25 ?C and 40 ?C.Spheres of emulsion droplet with puerarin nanocrystalline at the surface could be observed by SEM and AFM.The adsorption of puerarin at the surface of oil droplets could also be observed by CLSM and FIM.It could be deduced that nanocrystallines of puerarin adsorbed on the surface of oil droplets and formed a core-shell structure consisting of oil droplet as core.The cumulative realease of puerarin from Pu-NSSPE was 57.02% at 30 min,whichwas much higher than 33.45%of crude material and 38.72% of nanocrystallines,but had no significant difference from 52.79% of surfactant emulsion.The realease of puerarin from crude material,nanocrystallines,surfactant emulsion and NSSPE all reached a balance at 6 h.The cumulative realease was 73.75%,78.52%,86.69% and 82.53%,respectively.(3)Study on oral bioavailability of Pu-NSSPESprague-Dawley rats were divided into 4 groups randomly.Each group was admintted orally administrated puerarin raw material suspension,nanocrystals suspension,classic surfactant emulsion which used Tween 80 as emulisifier and Pu-NSSPE.Then blood samples were obtained from fossa orbitalis at different time points.The concentration of puerarin in blood was analyzed by HPLC method.The Pharmacokinetics were calculated by DAS program.For raw material suspension,nanocrystals suspension,surfactant emulsion and Pu-NSSPE,Tmax was 0.22 ? 0.14 h、0.22 ? 0.14 h、0.17 ? 00 h and 0.33 ? 0.18 h,respectively;Cmaxwas 634.17 ? 292.77ng?m L-1、1 881.44 ? 731.84 ng?mL-1、1 021.38 ? 359.49 ng?m L-1 and 3 226.14 ? 726.64ng?m L-1,respectively;AUC0-tare 1 903.05 ? 272.12 ng?mL-1?h-1、3 203.11 ? 1 021.48ng?mL-1?h-1、2 233.01 ? 341.56 ng?mL-1?h-1 and 4 994.22 ? 1 650.83 ng?mL-1?h-1,respectively.Compared with raw material suspension,nanocrystals suspension,surfactant emulsion,the relative bioavailability of Pu-NSSPE was 262.43%、155.92%and 223.65%,respectively.In this paper,a stable Pu-NSSPE with adsorption of puerarin at the surface of Rhizoma Chanxiong oil droplets c was developed.This new drug delivery system could enhance the oral bioavailability of puerarin.The research could set theoretical and technic foundation for the use of NSSPE in chinese medicine pharmaceutics,and provide a novel preparation for chinese medicine prescriptions containing insoluble ingredients eventually.