Preparation And Characterization Of Highly Water-soluble Propyl Gallate

The inclusion complexes of propyl gallate were prepared by propyl gallate?PG?and?-cyclodextrin??-CD?,hydroxypropyl-?-cyclodextrin?HP-?-CD?,dimethyl-?-cyclodextrin?DM-?-CD?,sulfobutyl-?-cyclodextrin?SBE-?-CD?.The best inclusion ratios,temperatures,times and stirring rates of PG/?-CD,PG/HP-?-CD,PG/DM-?-CD and PG/SBE-?-CD were determined by single factor tests and orthogonal tests.The solubility of the inclusion complexes were determined by UV spectrophotometry,the inclusion rates of the inclusion complexes were determined by high performance liquid chromatography?HPLC?.Then the inclusion complexes were characterized by fourier transform infrared spectroscopy?FT-IR?,X-ray diffraction?XRD?,differential scanning calorimetry?DSC?,scanning electron microscopy?SEM?.Finally,the antioxidant capacities of the inclusion complexes were evaluated by 1,1,1-diphenyl-2-trinitrophenyl hydrazine?DPPH?free radical method,2,2'-diazo-bis?3-ethylbenzothiazoline-6-sulfonic acid?,?ABTS?free radical method,hydroxyl free radical method and superoxide free radical method.The main test results are as follows:?1?The results of single factor tests and orthogonal tests showed that the best inclusion ratio of PG/?-CD inclusion complex was 1:1,the best inclusion temperature was 70?,the best inclusion time was 8h,and the best stirring rate was 500r/min.At these conditions,the average comprehensive score of the inclusion compound was86.62,and the average inclusion rate was 84.37%.The optimal inclusion ratio of PG/HP-?-CD inclusion complex was 1:1,the optimal inclusion temperature was50?,the optimal inclusion time was 6h,and the optimal stirring rate was 400r/min.At these conditions,the average comprehensive score of the inclusion complex is92.59,and the average inclusion rate is 91.26%.The optimal inclusion ratio of PG/DM-?-CD inclusion complex is 1:1,the optimal inclusion temperature was 60?,the optimal inclusion time was 4h,and the optimal stirring rate was 400r/min.At these conditions,the average comprehensive score of the inclusion compound was 92.35,and the average inclusion rate was 92.32%.The optimal inclusion ratio of PG/SBE-?-CD inclusion complex was 1:1,the optimal inclusion temperature was50?,the optimal inclusion time was 6h,and the optimal stirring rate was 500r/min.At these conditions,the average comprehensive score of the inclusion complex was91.34,and the average inclusion rate was 90.85%.?2?The solubility of PG,PG/?-CD,PG/HP-?-CD,PG/DM-?-CD and PG/SBE-?-CD were determined by UV spectrophotometry,which were 3.37 mg/ml,49.69mg/ml,58.25 mg/ml and 21.61 mg/ml.Compared with PG,the solubility of four PG inclusion complexes increased by 18.7 times,276.1 times,323.6 times and 120.1times,respectively.?3?The inclusion rates of PG,PG/?-CD,PG/HP-?-CD,PG/DM-?-CD and PG/SBE-?-CD were 84.37%,91.26%,92.32%and 90.85%by HPLC,and the contents were 13.79%,12.03%,10.32%and 7.27%respectively.The results of FT-IR,XRD,DSC and SEM analysis showed that the inclusion complexes had been formed.?4?Free radical scavenging tests were used to evaluate the antioxidant capacities of inclusion complexes.DPPH free radical method:the EC₅₀values of PG and PG/?-CD,PG/HP-?-CD,PG/DM-?-CD and PG/SBE-?-CD were 6.61?g/ml,4.51?g/ml,4.50?g/ml,3.90?g/ml and 2.71?g/ml,respectively.The order of free radical scavenging ability was PG/SBE-?-CD>PG/DM-?-CD>PG/HP-?-CD>PG/?-CD>PG.ABTS free radical method:the EC₅₀values of PG and PG/?-CD,PG/HP-?-CD,PG/DM-?-CD and PG/SBE-?-CD were 8.02?g/ml,5.11?g/ml,4.14?g/ml,4.01?g/ml and 3.82?g/ml,respectively.The order of free radical scavenging ability was PG/SBE-?-CD>PG/DM-?-CD>PG/HP-?-CD>PG/?-CD>PG.Hydroxyl free radical method:the EC₅₀values of PG and PG/?-CD,PG/HP-?-CD,PG/DM-?-CD and PG/SBE-?-CD were 9.11?g/ml,6.09?g/ml,5.73?g/ml,5.32?g/ml and 4.79?g/ml,respectively.The order of free radical scavenging ability was PG/SBE-?-CD>PG/DM-?-CD>PG/HP-?-CD>PG/?-CD>PG.Superoxide free radical method:the EC₅₀values of PG and PG/?-CD,PG/HP-?-CD,PG/DM-?-CD and PG/SBE-?-CD were 8.34?g/ml,7.68?g/ml,6.86?g/ml,5.70?g/ml and 2.80?g/ml,respectively.The order of free radical scavenging ability was PG/SBE-?-CD>PG/DM-?-CD>PG/HP-?-CD>PG/?-CD>PG.