| Supermolecular is formed by host and guest molecular when a guest molecular is fully or partly included in the host molecular.Cyclodextrins(CD),have suitable molecular size and excellent biocompatibility,due to the unique structure with hydrophobic central cavity,they can selectively bind different guest molecules to form inclusion complexes.When the drug is included into the cavity of the cyclodextrin molecule,some interactions will happen and thus the pharmaceutical properties will be improved.Thus cyclodextrins have been widely used in many different fields,such as pharmaceutics,analytics,food and environment,etc in recent years.In this paper,the use ofβ-cyclodextrin,hydroxypropyl-β-cyclodextrin and different substituted sulfated cyclodextrins as host molecules was investigated.The complexes of the cyclodextrins mentioned above with several poor water-soluble anti-cancer drugs were prepared and identified,and their molecular recognition behaviors were studied using several methods.The experiments included the following three parts:1.The molecular recognition behaviors between 5-fluorouracil and the following host moleculesβ-CD,HP-β-CD,6-β-CDS,2-β-CDS were studied.UV-Vis method was used to calculate the stability constants and inclusion ratio.The results showed that inclusion complexes were formed between the host and guest molecules with the molar ratios of 1:1;the stability of inclusion complexes was related to substituted functions and the hydrophobicity of the substituted functions;β-CDS showed the best complexation ability with the guest molecules,and the complexation constant of 2S-β-CD on the guest molecules was higher than that of 6-β-CD.The inclusion complexes of cyclodextrins with 5-fluorouracil were also characterized by IR,DSC.2.The inclusion and solubility improvement of Curcumin with five cyclodextrins (β-CD,HP-β-CD,6-β-CDS,2-β-CDS,β-CDS)were studied in citrate buffer solution (pH=2).The solubility improvement of curcumin with the five cyclodextrins mentioned above was studied in saturated solutions.The fluoresence spectrophotometric titrations had been performed in buffer solution(pH=2.0),and the complexes stability constants(K)formed by the five cyclodextrins with curcumin were also calculated.The results showed that:all host molecules and guest molecule formed inclusion complex with the molar ratios of 1:1;The solubility of curcumin is improved in the five cyclodextrins solutions,in which HP-β-CD is the best,β-CDS was after HP-β-CD;The fluorescence intensity of curcumin was also improved in the five cyclodextrins solutions,in which HP-β-CD andβ-CDS are better.The fluoresence enhancement factors are up to 17 and 19 when their concentrations are 3×10-2M.Inclusion constant K formed by cyclodextrins with cureumin is 129,397680, 15562,52054,79956 respectively.3.Interactions between different concentration of cyclodextrins and docetaxel were studied using circular dichroism spectra in water.The inclusion compounds were prepared with lyophilization technique.The measurements of the inclusion molar ratio of the host to guest molecules,apparent complexation constants,the thermodynamic parameters and the identication of the inclusion complex were carded out by the methods such as continuous variation method,UV absorption spectroscopy,phase solubility diagram,differential scanning calorimeter(DSC)and infrared spectra(IR) methods,respectively.The circular dichroism results showed that the positive and negative band of docetaxel had the biggest increase in strength when docetaxel interacted withβ-CD.Inclusion constant K formed by cyclodextrins with docetaxel is 521,147,65,179,467 respectively at room temperature.The inclusion complexes of cyclodextrins with docetaxel were characterized by IR,DSC.Thermodynamic parametersΔG,ΔH are negative,ΔS is negative determinated by phase solubility method,these showed that the inclusion process was exothermic spontaneously. |
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