| Magnolol and honokiol, which are major active ingredients of Magnolia officinalis,have the propertiesof anti-inflammatory, anti-viral, anti-bacterial anti-tumor,cholesterol-reduced function, anti-aging effect, and low toxicity. However, the defects of poor solubility and low stability, such as easily be oxidized, polymerized, and condensed under humid, high temperature or sunshine environments of magnolol and honokiol limited them application. The defects could be overcome by the formation of nano/microspheres with chitosan through nanotechnology. At present, the preparation of magnolol, honokiol loaded nano/micro-spheres has been rarely reported. In these work, the optimal preparation conditions of magnolol, honokiol loaded chitosan nano/microspheres were determined and in vitro drugrelease behavior, antioxidant activity and cytotoxicityto cancer cells were studied. In order to enhance the targeting of nano/microspheres to cancers cells, folic acidwas conjugated to chitosan molecules to prepare magnolol-chitosannano/microspheres. What’s more, in order to verify the universality of the preparation method in this thesis, magnolol, honokiol molecular was replaced with resveratrol,which has thesimilar structure to magnolol and honokiol, to preparethe drug-loaded nano/microspheres. The main research work are as follows:1. Study on the preparation and biological activity of magnolol and honokiol-chitosan nano/microspheres.The drug-loaded chitosan nano/microspheres were prepared using the ionic crosslinking method. The optimal preparation conditions were determined by adjusting the pH value, the concentration of sodium tripolyphosphate, poloxamer 188 and ethanol,respectively. The morphology and size of nano/microspheres were observed by atomic force microscopy(AFM). The drug-loadednano/microspheres were farther characterized by ultraviolet spectroscopy(UV),fouriertransform infrared spectroscopy(FT-IR) and X-ray powder diffraction(XRD).Thestability and dispersibilityof the nano/microspheres in solution were ascertained by dynamic light scattering method(DLS). The composition of nano/microspheres and the thermal stability of drugswere confirmed by differential scanning calorimetry(DSC) and thermogravimetric analysis(TG). Thedrug loading capacityand the encapsulation efficiency of nano/microsphereswere determind by high performance liquid chromatography(HPLC).The drug release in vitro was measured though the UV method.Theability of free radical scavenging of nano/microspheres was assayed through1, 1-pheny-2-picrylhydrazyl(DPPH?) method. The cytotoxicity of nano/microspherestocancer cellswas measured by MTT method. The results showed that themagnolol and honokiol chitosannano/microspheres were successfully prepared. The drug loading capacity and encapsulation efficiency of magnolol-chitosan nano/micro-spheres was 81.71?g/mg,20.27%, respectively,well ashonokiol-chitosannano/micro-spheres was 240.64??g/mg,59.68%, respectively. Thedrug-loaded nano/microspheresappeared a controlled and sustained release effect, uniform particle size about 100 nm, better dispersion, good stability, antioxidant activity and antitumor activity. In order to study in vitro uptake ability of cells for drug-loaded nano/microspheres, FITC was marked to chitosan to prepare fluorescently labeled magnolol-chitosan nano/microspheres. The results showed that L02 and SMMC7721 cells can uptake the nano/microspheres easily and cancer cell appeared more uptake.2. Study on the preparation and antitumor activity of magnolol-folate-chitosan nano/microspheres. The folic acid molecules were conjugated to chitosan molecules by acylation reaction, which serves as carrier, magnolol-chitosan and folic acid targeted nano/microspheres was prepared under optimal reaction conditions. The morphology, size,stability and dispersibility in solution of the nano/microspheres were characterized respectively. The drug loading capacity and the encapsulation efficiency of the nano/microspheres were determined, and in vitro drug release behavior was studied. The results showed that thenano/microspheres had good stability, uniform particle size about180 nm, good dispersion. The drug loading capacity was 155.09 ?g/mg and encapsulation efficiency was 38.46%. The drug release rate was faster in acidic environments than that inneutral environments furthermore, the nano/microsphereswas pH-responsive. The cytotoxicity of the nano/microspheres treated SMMC7721 cells is higher than thosetreated L02 cells, the nano/microspheres have a certain of targeting which the role played by folic acid mediated so that they can affordsenhanced antitumor efficacy.3. Study on the preparation of resveratrol-chitosannano/microspheres.The optimal preparation conditions for resveratrol-loaded nano/microspheres. The morphology, size,stability and dispersibility in solution of the nano/microspheres were characterized respectively. The drug loading capacity and the encapsulation efficiency of the nano/micro-spheres were measured.The results indicated that the nano/microspheres hadgood stability,uniform particle size about 150 nm, and well dispersion.The drug loading capacity was 48.81 ?g/mg and encapsulation efficiency was 11.71%.The above results verified the universality of the nano/microspheres preparation method. |
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