| The oil water partition coefficient(n-Octanl/water partition coefficient,Kow)--an important parameter for characterizing biological activity and many methods have been used to determine the Kow value.Although there are a variety of methods to determine the Kow,but reversed-phase high performance liquid chromatography has become an important method for rapidly,accurately and high-throughputly to predict Kow by determinating retention factor(k)of substance and establishing the QSRR model between k and Kow in chromatographic systemThis paper takes this as background,we studied the influence factors of logkw.The QSRRmodel was established to predict kow of compounds in complex system of Chinese herbal medicine.In addition,The quantitative retention activity relationship was fitted by the activity test.The main research contents are as follows:1 Literature reviewIn this paper,we reviewed the pharmacological action of pyridine alkaloid and the construction and application of QSRR model,in order to provide the research basis and theoretical support for the experimental development.2 The study on the influence factors of logkwThe acid,neutral and basic compounds were chosen to be as the research object,select the appropriate mobile phase for every kind compound.Retention times were determined under different chromatographic conditions(such as different chromatographic columns,instruments,column temperatures,solvent temperatures)with 4 suitable methanol water of two mobile phases for methanol volume ratio between 0.1 and 0.95,and then logkw was obtained by Snyder-Soczewinski equation for acid,neutral and basic representative compounds.The results indicated that RSDs of logkw on different C18 columns were in the range between 0.8%and 3.4%;RSDs of logkw on different instruments and solvent temperatures were less than 2.7%and 1.7%,respectively.The RSDs of logkw with Tc changed from 20℃ to 60℃ were up to 6.1%～13.1%;good linear relationships(R2>0.99)were observed between logkw and 1/Tc(column temperature),which were called Van’t Hoff equation.Therefore,it can be concluded that the main factor affecting logkw is column temperature for compounds on chromatographic columns with same silica gel carrier,but logkw can be corrected by Van’t Hoff equation.3 Establishment and verification of QSRR modelIn this chapter,a set of 31 pyridine alkaloid with reliable experimental Kow data was chosen as model compounds for establishing linear relationship between the logarithm of apparent n-octanol/water partition coefficient(logKow")and the logarithm of RP-HPLC retention factor of the solutes corresponding to the neat aqueous fraction of mobile phase(logkw)as the QSRR model.The mixture of methanol-water was used as mobile phase at different pH,and retention time(tR)was corrected by a dual-point retention time correction(DP-RTC)in this process.The result showed the QSRR model has a good linear relationship(R2=0.941～0.952)with satisfactory results of internal and external validation(the cross-validated correlation coefficient R2cv of 0.912-0.925,and 3.2%<relative error(RE)≤9.9%for all the 6 verification compounds)which indicating the prediction of model is accurate and reliable.4 Prediction of Kow value of effective components in traditional Chinese Medicine by QSRR modelThe Kow values of effective pyridine alkaloids components in traditional Chinese medicine Coptis chinensiswere predicted by QSRR model,then compared with calculated Kow value by ACDLab software and the SFM test values that recommended by Organization for economic cooperation and development(OECD).The result showed that the predicted values of the model are consistent with the experimental values(RE=0.8%～7.6%)in addition to individual compounds,and the comparison between the calculated values and the experimental values shows that the model has higher accuracy,at the same time showed that this model can be applied to the prediction of the Kow value of compounds in complex systems,such as traditional Chinese medicine and soil.The method is simple and fast,which is not necessary to separate the components of the complex Chinese medicinal materials to obtain the monomers and and just need to analysis traditional Chinese medicinal materials directly.5 The construction of QRAR modelIn this part,a set of 13 pyridine alkaloid was chosen as model compounds which logkw obtained by Snyder-Soczewinski equation and IC50 obtained by modified Ellman method.The result showed that a good linear relationship was established beween logkw and IC50 of five berberine alkaloid with R2 is 0.93 which can be used for the prediction of IC50 of such analogous structure compounds(berberine alkaloid).However,due to lack of data,it needs for further verification. |
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