Study On Cucurbit[n]urils As Drug Carrier And Chemical Constituents Of Tripterygium Wilfordii

Cucurbituril(CB),as a type of novel synthetic acceptor,has attracted considerable attentions of chemists.Studies in the field of their molecular recognition, supramolecular catalysis and molecular assembly have been widely carried out. However,the study for cucurbituril as the drug carrier is not sufficient,few papers have been reported.In present thesis,using Camptothecin,Chlorambucil and 5-aminosalicylic acid with different mechanism as model drugs,the potential utilization of CB[n]in the drug delivery were investigated.1.The recent research progress of cucurbituril including synthesis of cucurbituril and their derivatives,their molecular recognition,supramolecular catalysis,molecular assembly and application was reviewed.2.The synthesis and separation of CB[n](n=6,7,8) have been studied,and the interaction between cucurbituril and guests has been firstly studied by HPLC method. The results reveal that the new attempt has the characteristic of credibility and direct-viewing,and the conclusions from HPLC method are consistent with that of absorption spectroscopy and ¹H NMR technique.Interaction model of host and guest by using the value of k′_G·Q and apparent K is also its feature.3.Study on cucurbituril as anti-cancer drug camptothecin(CPT) carrier(1) The experiments on cucurbti[n]uril(n=6,7,8) of acute toxicity and vitro cytotoxicity provided the evidences to be safe as potential carriers.(2) The interaction between cucurbit(n)uril(n=7,8)(CB[n]) with two forms namely lactone modality and carboxylate modality of anticancer drug camptothecin (CPT) was studied.The results revealed that the combination between CB[n]with the lactone form of CPT was observed by electronic absorption spectroscopy, fluorescence spectroscopy and ¹H NMR technique in the acid solution(pH=2) and the total stability constantsβwere also obtained by Job plot with a host:guest ratio of 2:1;while in the phosphate buffer solution(pH=7.4),only CB[8]bound the carboxylate form of CPT in ratio 1:1,but no obvious interaction between CB[7]and the carboxylate form of CPT was observed.(3) The solubility of CPT was enhanced up to about 70 times and 8 times due to the formation of interaction complexes with CB[7]and CB[8]respectively by using phase solubility method.(4) Inclusion complexes of a slightly water soluble camptothecin(CPT) with cucurbit[n=7,8]uril prepared by co-evaporation method were characterized by Fourier transformation-infrared spectroscopy,differential thermal analysis,Power X-ray diffraction and ¹H NMR technique.The possible inclusion model was proposed that the quinoline ring of CPT was encapsulated into the cavity of the title CB[n]s.(5) The behavior of controllable drug release from CPT,CB[n]-CPT physical mixtures and inclusion complexes were investigated at buffer solutions with different pH values.The results revealed that the release rate for CB[n]-CPT inclusion complexes was the fastest at pH2.0,then in water,the least release rate was at pH7.4, which indicating that the rate of drug release can be effectively controlled by altering the pH values of the environment.(6) The potential of CB[7]or CB[8]for stabilizing lactone modality of CPT was also investigated by using HPLC method in simulated physiological environment (phosphate buffer solution,pH=7.4 at 37℃).The results revealed that more than 60%CPT in presence of CB[7]or CB[8]remained in its lactone form for 5 h compared to only 36%CPT in absence of CB[7]or CB[8],indicating that CB[n] have a certain ability to protect the lactone form of CPT from influence of solvent to change into the carboxylate form.(7) A preliminary in vitro assay by using MTT method revealed that the anticancer activity of CPT was not affected remarkably by the inclusion interaction.4.Study on cucurbituril as anti-cancer drug chlorambucil(CHB) carrier(1) The interaction between cucurbit[n]uril(n=7,8) with chlorambucil at different values of pH was researched by using fluorescence spectroscopy andβ-CD was as contrapose.Cucurbit[n]uril(n=7,8) could bind chlorambucil in a ratio 1:1 at pH 2.0,4.0,6.0 buffer solution,however 1:1 formation of complexes withβ-CD were obtained in acid solution and weak basic solution.(2) The formation and physicochemical characterization of solid inclusion complexes were investigated by Fourier transformation-infrared spectroscopy(FTIR), differential scanning calorimetry(DSC),thermal gravity(TG) and ¹H NMR experiments.The results showed that the thermal stability of CHB was increased by cucurbit[n]uril(n=7,8) inclusion complexes,while no obvious reform was observed forβ-CD complex.The in vitro dissolution studies indicated that the dissolution rates were remarkably increased in inclusion complexes,compared with the physical mixture and drug alone.(3) The dynamics of solid inclusion complexes toward guanosine was studied by UV spectroscopy and ¹H NMR technique.The results revealed that the formation of mixtures could slow the rate of reaction by at least 2～3-fold and result in reducing the unwanted side effects of chlorambucil.A preliminary in vitro assay using various tumor cell lines(HL-60,Hela,Siha) revealed no decrease or moderate decrease in activity by encapsulation of three carriees.5.Investigation of CB[7]as 5- aminosalicylic acid(5-ASA) for Colon-specific drug delivery(1) The interaction between cucurbit(7)uril(CB[7]) and 5-aminosalicylic acid (5-ASA) at different values of pH was studied by fluorescence spectroscopy and HPLC method.The results revealed that CB[7]bound 5-ASA with a ratio of 1:1 at pH＜6.0,while no obvious interaction between CB[7]and 5-ASA was observed at pH＞6.0.(2) The thermodynamic parameters for the CB[7]-5-ASA complex were determined in temperature-dependent binding studies.From the temperature dependence of equilibrium constants,ΔG,ΔH andΔS have been negative in sign, indicating an enthalpic driving force for complexation and an energetically favored reaction.(3) According to the gastric and intestinal pH values,the forms of complexes in different buffer solutions were further confirmed by ¹H NMR technique.The results showed that the inclusion complex of CB[7]-5-ASA was dominant in acidic aqueous solution,while free 5-ASA drug molecules were released at pH＞6.0 due to the decomposition of the inclusion complex,indicating that the interaction between CB[7] with 5-ASA was dependent on the values of pH.CB[7]could be used as a potential 5-ASA colon-specific drug delivery.In present thesis,95%ethanolic extract from Tripterygium wilfordi was examined and 17 compounds were purified and identified.Moreover,the contents of tricin in total plant and in different plant parts from three kinds of Ranunculus plants namely R.sceleratus,R.japonicus and R.cantoniensis in Guizhou were first determined by HPLC method,and the contents of total flavones were also analyzed by UV-spectrophotometer.