Preparation And Characterization Of Oridonin Bile Salt-phosphatidylcholine Mixed Nano-micelle

OBJECTIVE: The aim of current study was to prepare and characterize Bile salt-phosphatidylcholine mixed nano-micelle (BS/PC-MM) systems to enhance the solubility of the poorly water-soluble drug, oridonin. BS/PC-MM systems is a kind of biocompatibility and safety carrier, which could not only improve the solubility of poorly soluble drugs, but also enhance the therapeutic effect and decrease the adverse drug reactions. This system has been widely studied for solubilization of drugs with poor solubility in abroad, such as Docetaxel, Teniposide and Diazepam derivatives. Colloidal particles with nanoscale such as between 10nm and 100nm, could not only improve the solubility of the drug, but also enhance its bioadhesive. Oridonin, an cytotoxic agent for the treatment of various cancers, especially for gastrointestinal cancer, has been widely attentioned for its promising biological effects. However, its poor solubility both in water and in lipid has restricted its clinical applications. So far, there was no matching preparation for it. Our purpose was to develop a novel mixed nano-micelle system for it, which could dramatically improve its solubility, and obtain nanoscale drug delivery systems.METHODS: The solubility of oridonin in styles of solvent were determined. The oridonin phospholipid complex was prepared by solvent evaporation. The thermodynamic properties of oridonin phospholipid complex was studied by Differential Scanning Calorimetry. The state of oridonin in complex was studied by X-Ray diffraction. Wheather new chemical bonds appearance were studied by UV-Vis. The dispersion of oridonin phospholipid complex in water was studied through abserving crystals of oridonin by microscope. BS/PC-MM were prepared by the coprecipitation method.The dissolving capacity of bile salt to phosphatidylcholine was studied by UV-Vis. The influence of the type of PC/BS, PC mol fraction, total lipid concentration, pH value, ironic strength and water temperature on the drug solubility were investigated in detail by HPLC.While the stability after dilution and the degeration at 60℃were determined. The properties of BS/PC-MM including the size, the zeta potential, and the surface morphology were sudied by laser particle size analyzer and transmission electron microscope. The fluorescence spectra of different molar concentration of BS/PC-MM were measured, in which pyrene was solubilized and used as fluorescence probe, and the aggregation behavior of BS/PC-MM was studied by Origin softwear through curve fitting. We investigate the antineoplastic activity by MTT and safety by blood cell haemolysis test on ORI-BS/PC-MM.RESULTS: The solubility of oridonin in water and common lipid was very slightly soluble, but had good values in some organic solvents. The peak of melting point changed in the DSC spectra, which means a new phase transformation happened. The crystallogram shows that oridonin could disperse in an amorphous form in phospholipid, meanwhile the peaks of crystal diffraction disappear. In conclusion, we successfully prepared oridonin phospholipid complex, but instability and could easily separate crystals out in water. We successfully prepared oridonin bile salt-phosphatidylcholine mixed nano-micelle(ORI-BS/PC-MM). SDC could increase the concentration of SPC well in water while SDC/SPC-MM could increase the the concentration of oridonin well in water when SPC mol fractions was less than 0.4 at room temperature and using ultrapure water. When SPC mol fractions was 0.4, total lipid concentration was 10%, the solubility of oridonin was (19.74+0.96mg·mL^-1). When SPC mol fractions was 0.4, total lipid concentration was 5%, the solubilization efficiency and solubility of oridonin were (27.87+1.77)% and (13.94+0.89) mg·mL^-1. The blank solutions of BS/PC-MM were normally clear and colorless, meanwhile the ORI-BS/PC-MM solutions were canary yellow with an average size (10.92+2.90)nm, and the Zeta potential was-(48.75+2.37)mV. The size of ORI-BS/PC-MM was nearly 10nm, homodisperse and oval determined by transmission electron microscope. The prepared ORI-BS/PC-MM was stable after dilution at room temperature for 5 days. The critical micelle concentration(CMC) of BS/PC-MM with different PC/BS value were respectively 0.034 g·L^-1,0.048g·L^-1,0.055 g·L^-1. Hemolysis test suggests that the ORI-BS/PC-MM is safety. The inhibition of rate to HepG2 cell of the ORI-BS/PC-MM suggests that the ORI-BS/PC-MM has greatly antitumor effect.CONCLUSION: The oridonin phospholipid complex was instability in water which could not be drug delivery system for oridonin single-handed.The BS/PC-MM could significantly increase the concentration of ORI in water, and the ORI-BS/PC-MM with a narrow range of size and high solubility were attainable. BS/PC-MM may be promising vectors for delivery oridonin .