Atoms in most organic molecules are often carbon,oxygen,nitrogen,sulfur,halogens,etc. Based on the three-dimensional structure of a molecule,a molecular structural characterization（MSC） method called improved molecu...Atoms in most organic molecules are often carbon,oxygen,nitrogen,sulfur,halogens,etc. Based on the three-dimensional structure of a molecule,a molecular structural characterization（MSC） method called improved molecular electronegativity-distance vector（I-MEDV） was developed. It was used to describe the structures of 37 compounds of styrax japonicus sieb flowers. Through multiple linear regression（MLR）,a QSRR model was built up. The correlation coefficient（R1） of the model was 0.980. Then,4 vectors were selected to build another model through the method of stepwise multiple regression（SMR） ,and the correlation coefficient（R2） of the model was 0.975. Moreover,all the two models were evaluated by performing the crossvalidation with the leave-one-out（LOO） procedure and the correlation coefficients（Rcv） were 0.948 and 0.968,respectively. The results show that the I-MEDV could successfully describe the structures of organic compounds. The stability and predictability of the models were good.展开更多
The molecular electronegativity-distance vector （MEDV） was used to describe the molecular structure of volatile components of Rosa banksiae Ait, and QSRR model was built up by use of multiple linear regression （MLR...The molecular electronegativity-distance vector （MEDV） was used to describe the molecular structure of volatile components of Rosa banksiae Ait, and QSRR model was built up by use of multiple linear regression （MLR）. Furthermore, in virtue of variable screening by the stepwise multiple regression technique, the QSRR models of 10 and 6 variables and linear retention index （LRI） 10, 7 and 6 varieables were built up by combinating MEDV with the Ultra2 column GC retention time （tR） of 53 volatile components of Rosa Banksiae Air. The multiple correlation coefficients （R） of modeling calculation values of QSRR model were 0.906, 0.906, 0.949, 0.943 and 0.949, respectively. The cross-verification multiple correlation coefficients （RCV） were 0.903, 0.904, 0.867, 0.901 and 0.904, respectively. The results show that the models constructed could provide estimation stability and favorable predictive ability.展开更多
A molecular structural characterization （MSC） method called reduced molecular electronegativity-distance vector （MEDVR） was used to describe the molecular structures of 55 components of meconopsis integrifolia flo...A molecular structural characterization （MSC） method called reduced molecular electronegativity-distance vector （MEDVR） was used to describe the molecular structures of 55 components of meconopsis integrifolia flowers. By use of stepwise multiple regression （SMR） and partial least square （PLS） methods, a model with the correlation coefficient （R1） of 0.987 and the standard deviation （SD1） of 1.377 could be obtained. Then through multiple linear regression （MLR）, another model with the correlation coefficient （R2） of 0.989 and standard deviation （SD2） of 1.395 could be constructed. Furthermore, in virtue of variable screening by the stepwise multiple regression technique （SMR）, 8 vectors were selected to build up another model with its correlation coefficient （R3） and standard deviation （SD3） of 0.989 and 1.366, respectively. Then all the three models were evaluated by performing cross-validation with the leave-one-out （LOO） procedure, and the correlation coefficients （QCV） were 0.981, 0.976 and 0.979, respectively. The results show that the models constructed could provide estimation stability and favorable predictive ability.展开更多
The study dealed with quantitative structure-activity relationship(QSAR)to explore the important features of diketo acid(DKA)derivatives for exerting potent HIV-1 integrase inhibitors activity.A three-step screening m...The study dealed with quantitative structure-activity relationship(QSAR)to explore the important features of diketo acid(DKA)derivatives for exerting potent HIV-1 integrase inhibitors activity.A three-step screening method was proposed to choose descriptors.Then,additional descriptors were used in the CoMFA and CoMSIA.Lastly,a modified CoMSIA m7 model,constructed by adding Csp^2_03_F descriptor,showed better predictive ability.Validation parameters(Q^2 and R^2)for the models were 0.722 and 0.925,respectively.In addition,external validation for the models using a test group revealed R^2pred=0.892.Contour maps analysis defined favored and disfavored regions of the compounds,and two new compounds with the descriptor structure were designed with better activities than Raltegravir(RAL),well drug-likeness and low toxicity.The research provides a base for further DKA development.展开更多
In this paper, the comparison of orthogonal descriptors and Leaps and Bounds regression analysis is performed. The results obtained by using orthogonal descriptors are better than that obtained by using Leaps and Boun...In this paper, the comparison of orthogonal descriptors and Leaps and Bounds regression analysis is performed. The results obtained by using orthogonal descriptors are better than that obtained by using Leaps and Bounds regression for the data set of nitrobenzenes used in this study. Leaps and Bounds regression can be used effectively for selection of variables in quantitative structure activity/property relationship(QSAR/QSPR) studies. Consequently, orthogonalisation of descriptors is also a good method for variable selection for studies on QSAR/QSPR.展开更多
【目的】目前驱避剂的作用机理研究还不理想,本研究从单个萜类驱避化合物分子与不同种类引诱气味分子同时相互缔合的角度入手,通过理论计算探究该缔合与蚊虫驱避作用的关系,从而为驱避作用机理研究提供新认识。【方法】利用Gaussian Vie...【目的】目前驱避剂的作用机理研究还不理想,本研究从单个萜类驱避化合物分子与不同种类引诱气味分子同时相互缔合的角度入手,通过理论计算探究该缔合与蚊虫驱避作用的关系,从而为驱避作用机理研究提供新认识。【方法】利用Gaussian View4.1和Gaussian03W软件构建和优化萜类驱避化合物单体、单体与引诱物L-乳酸及氨分子同时缔合后三分子缔合体的结构,获得其最低能量结构和缔合能;通过程序Ampac 8.16将前述结构导入到程序Codessa 2.7.10,计算各类结构描述符;再利用Codessa 2.7.10的启发式方法得到一系列缔合体结构描述符与驱避活性之间的定量关系模型,并通过转折点确定、模型验证后确定最佳定量关系计算模型。【结果】三分子缔合的缔合能基本上在20~50 kJ/mol的范围,所得最佳三参数定量计算模型的R2值为0.9098,包含的3个结构描述符分别是三分子缔合体的maximum nucleophilic reactivity index for a C atom,topographic electronic index（all bonds）[Zefirov’s PC]和exchange energy＋e-e repulsion for a H-O bond。【结论】萜类驱避化合物分子可同时与2个不同种类的引诱物分子发生缔合作用,该缔合作用符合氢键的能量基本特征;缔合体的碳原子最大原子核反应指数、所有键的拓扑电子指数、氢氧键电子间交换互斥能对驱避活性影响显著。这些结果初步说明萜类驱避化合物与引诱物三分子缔合作用确实存在,且该缔合作用对驱避活性具有显著影响,这为驱避机理的研究提供了新的理论依据。展开更多
以20种天然氨基酸的721个3D结构信息描述子经主成分分析,得出一种新的氨基酸描述子——SVTD(Scores Vector of Three Dimension Descriptors),将其应用于血管紧张素转化酶抑制剂与促凝血酶原酶抑制剂的结构表征,并应用偏最小二乘建模方...以20种天然氨基酸的721个3D结构信息描述子经主成分分析,得出一种新的氨基酸描述子——SVTD(Scores Vector of Three Dimension Descriptors),将其应用于血管紧张素转化酶抑制剂与促凝血酶原酶抑制剂的结构表征,并应用偏最小二乘建模方法建立定量构效关系模型,建模复相关系数R2cum、交互检验复相关系数Q2cum分别为0.880、0.778和0.998、0.804。结果表明:SVTD描述子能够系统地表征与生物活性相关的结构信息,该描述子有望成为多肽定量构效关系研究中一种有效的结构表达方法。展开更多
从20种天然氨基酸的41个分子轮廓指数（randic molecular profiles,R）、44个分子特征值指数（eigenvalue based indices,E）和47个分子运转路径数目（walk and path counts,W）分别进行主成分分析,得出1种新的氨基酸描述符（scores vec...从20种天然氨基酸的41个分子轮廓指数（randic molecular profiles,R）、44个分子特征值指数（eigenvalue based indices,E）和47个分子运转路径数目（walk and path counts,W）分别进行主成分分析,得出1种新的氨基酸描述符（scores vector of R,E,W-SVREW）。将其应用于血管紧张素转化酶（ACE）抑制二肽、三肽、四肽、九肽结构表征,应用多元线性回归建立定量构效关系模型,同时采用内部与外部双重验证的方法验证模型的稳定性。所建ACE抑制二肽、三肽、四肽、九肽的模型复相关系数（Rcum^2）、留一法（LOO）交互校验复相关系数（Rcv^2）和外部样本校验相关系数（Qext^2）分别为：0.907、0.791、0.633;0.831、0.603、0.723;0.834、0.668、0.718;0.964、0.853、0.948。经研究表明：SVREW描述符应用于ACE抑制肽结构表征所建模型稳定性与预测能力均较好。展开更多
The logarithms of retention factors normalized to a hypothetical pure water eluent(log k w) were determined on a reversed phase high performance liquid chromatography(RP HPLC) column (Li Chrosorb RP 18 column...The logarithms of retention factors normalized to a hypothetical pure water eluent(log k w) were determined on a reversed phase high performance liquid chromatography(RP HPLC) column (Li Chrosorb RP 18 column) for 20 new α\|branched phenylsulfonyl acetates. The atomic charge method was applied to develop quantitative structure retention relationships(QSRRs). Among the available geometric and electronic descriptors, surface area (S), ovality (O), and the charge of carboxyl group(Q OC ) are significant. In the model, the contribution of surface area (S) is the greatest. The molecular mechanism of retention was demonstrated through the model. With the correlation coefficient ( r 2 adj , adjusted for degrees of freedom) of 0.964, the standard error of 0.164 and the F value of 170.39, the model has good predictive capacity.展开更多
基金supported by the Youth Foundation of Education Bureau,Sichuan Province (09ZB036)Technology Bureau,Sichuan Province (2006j13-141)
文摘Atoms in most organic molecules are often carbon,oxygen,nitrogen,sulfur,halogens,etc. Based on the three-dimensional structure of a molecule,a molecular structural characterization（MSC） method called improved molecular electronegativity-distance vector（I-MEDV） was developed. It was used to describe the structures of 37 compounds of styrax japonicus sieb flowers. Through multiple linear regression（MLR）,a QSRR model was built up. The correlation coefficient（R1） of the model was 0.980. Then,4 vectors were selected to build another model through the method of stepwise multiple regression（SMR） ,and the correlation coefficient（R2） of the model was 0.975. Moreover,all the two models were evaluated by performing the crossvalidation with the leave-one-out（LOO） procedure and the correlation coefficients（Rcv） were 0.948 and 0.968,respectively. The results show that the I-MEDV could successfully describe the structures of organic compounds. The stability and predictability of the models were good.
文摘The molecular electronegativity-distance vector （MEDV） was used to describe the molecular structure of volatile components of Rosa banksiae Ait, and QSRR model was built up by use of multiple linear regression （MLR）. Furthermore, in virtue of variable screening by the stepwise multiple regression technique, the QSRR models of 10 and 6 variables and linear retention index （LRI） 10, 7 and 6 varieables were built up by combinating MEDV with the Ultra2 column GC retention time （tR） of 53 volatile components of Rosa Banksiae Air. The multiple correlation coefficients （R） of modeling calculation values of QSRR model were 0.906, 0.906, 0.949, 0.943 and 0.949, respectively. The cross-verification multiple correlation coefficients （RCV） were 0.903, 0.904, 0.867, 0.901 and 0.904, respectively. The results show that the models constructed could provide estimation stability and favorable predictive ability.
基金supported by the Foundation of Education Bureau, Sichuan Province (09ZB036)Technology Bureau, Sichuan Province (2006j13-141)
文摘A molecular structural characterization （MSC） method called reduced molecular electronegativity-distance vector （MEDVR） was used to describe the molecular structures of 55 components of meconopsis integrifolia flowers. By use of stepwise multiple regression （SMR） and partial least square （PLS） methods, a model with the correlation coefficient （R1） of 0.987 and the standard deviation （SD1） of 1.377 could be obtained. Then through multiple linear regression （MLR）, another model with the correlation coefficient （R2） of 0.989 and standard deviation （SD2） of 1.395 could be constructed. Furthermore, in virtue of variable screening by the stepwise multiple regression technique （SMR）, 8 vectors were selected to build up another model with its correlation coefficient （R3） and standard deviation （SD3） of 0.989 and 1.366, respectively. Then all the three models were evaluated by performing cross-validation with the leave-one-out （LOO） procedure, and the correlation coefficients （QCV） were 0.981, 0.976 and 0.979, respectively. The results show that the models constructed could provide estimation stability and favorable predictive ability.
基金Supported by the Project of the Beijing Municipal Commission of Education,China(No.KM201410005030)the Importation and Development of High-caliber Talents Project of Beijing Municipal Institutions,Chinathe National Natural Science Foundation of China(No.31100523).
文摘The study dealed with quantitative structure-activity relationship(QSAR)to explore the important features of diketo acid(DKA)derivatives for exerting potent HIV-1 integrase inhibitors activity.A three-step screening method was proposed to choose descriptors.Then,additional descriptors were used in the CoMFA and CoMSIA.Lastly,a modified CoMSIA m7 model,constructed by adding Csp^2_03_F descriptor,showed better predictive ability.Validation parameters(Q^2 and R^2)for the models were 0.722 and 0.925,respectively.In addition,external validation for the models using a test group revealed R^2pred=0.892.Contour maps analysis defined favored and disfavored regions of the compounds,and two new compounds with the descriptor structure were designed with better activities than Raltegravir(RAL),well drug-likeness and low toxicity.The research provides a base for further DKA development.
文摘In this paper, the comparison of orthogonal descriptors and Leaps and Bounds regression analysis is performed. The results obtained by using orthogonal descriptors are better than that obtained by using Leaps and Bounds regression for the data set of nitrobenzenes used in this study. Leaps and Bounds regression can be used effectively for selection of variables in quantitative structure activity/property relationship(QSAR/QSPR) studies. Consequently, orthogonalisation of descriptors is also a good method for variable selection for studies on QSAR/QSPR.
文摘【目的】目前驱避剂的作用机理研究还不理想,本研究从单个萜类驱避化合物分子与不同种类引诱气味分子同时相互缔合的角度入手,通过理论计算探究该缔合与蚊虫驱避作用的关系,从而为驱避作用机理研究提供新认识。【方法】利用Gaussian View4.1和Gaussian03W软件构建和优化萜类驱避化合物单体、单体与引诱物L-乳酸及氨分子同时缔合后三分子缔合体的结构,获得其最低能量结构和缔合能;通过程序Ampac 8.16将前述结构导入到程序Codessa 2.7.10,计算各类结构描述符;再利用Codessa 2.7.10的启发式方法得到一系列缔合体结构描述符与驱避活性之间的定量关系模型,并通过转折点确定、模型验证后确定最佳定量关系计算模型。【结果】三分子缔合的缔合能基本上在20~50 kJ/mol的范围,所得最佳三参数定量计算模型的R2值为0.9098,包含的3个结构描述符分别是三分子缔合体的maximum nucleophilic reactivity index for a C atom,topographic electronic index（all bonds）[Zefirov’s PC]和exchange energy＋e-e repulsion for a H-O bond。【结论】萜类驱避化合物分子可同时与2个不同种类的引诱物分子发生缔合作用,该缔合作用符合氢键的能量基本特征;缔合体的碳原子最大原子核反应指数、所有键的拓扑电子指数、氢氧键电子间交换互斥能对驱避活性影响显著。这些结果初步说明萜类驱避化合物与引诱物三分子缔合作用确实存在,且该缔合作用对驱避活性具有显著影响,这为驱避机理的研究提供了新的理论依据。
文摘以20种天然氨基酸的721个3D结构信息描述子经主成分分析,得出一种新的氨基酸描述子——SVTD(Scores Vector of Three Dimension Descriptors),将其应用于血管紧张素转化酶抑制剂与促凝血酶原酶抑制剂的结构表征,并应用偏最小二乘建模方法建立定量构效关系模型,建模复相关系数R2cum、交互检验复相关系数Q2cum分别为0.880、0.778和0.998、0.804。结果表明:SVTD描述子能够系统地表征与生物活性相关的结构信息,该描述子有望成为多肽定量构效关系研究中一种有效的结构表达方法。
文摘从20种天然氨基酸的41个分子轮廓指数（randic molecular profiles,R）、44个分子特征值指数（eigenvalue based indices,E）和47个分子运转路径数目（walk and path counts,W）分别进行主成分分析,得出1种新的氨基酸描述符（scores vector of R,E,W-SVREW）。将其应用于血管紧张素转化酶（ACE）抑制二肽、三肽、四肽、九肽结构表征,应用多元线性回归建立定量构效关系模型,同时采用内部与外部双重验证的方法验证模型的稳定性。所建ACE抑制二肽、三肽、四肽、九肽的模型复相关系数（Rcum^2）、留一法（LOO）交互校验复相关系数（Rcv^2）和外部样本校验相关系数（Qext^2）分别为：0.907、0.791、0.633;0.831、0.603、0.723;0.834、0.668、0.718;0.964、0.853、0.948。经研究表明：SVREW描述符应用于ACE抑制肽结构表征所建模型稳定性与预测能力均较好。
基金TheNationalNaturalScienceFoundationofChina (No .2 9837180 )
文摘The logarithms of retention factors normalized to a hypothetical pure water eluent(log k w) were determined on a reversed phase high performance liquid chromatography(RP HPLC) column (Li Chrosorb RP 18 column) for 20 new α\|branched phenylsulfonyl acetates. The atomic charge method was applied to develop quantitative structure retention relationships(QSRRs). Among the available geometric and electronic descriptors, surface area (S), ovality (O), and the charge of carboxyl group(Q OC ) are significant. In the model, the contribution of surface area (S) is the greatest. The molecular mechanism of retention was demonstrated through the model. With the correlation coefficient ( r 2 adj , adjusted for degrees of freedom) of 0.964, the standard error of 0.164 and the F value of 170.39, the model has good predictive capacity.
