Molecular Docking and 3D-QSAR Studies on a Series of Fused Heterocyclic Amides as B-Raf Inhibitors

B-Raf has been identified as promising targets for novel anticancer agents. To further explore the interactions between small molecules and B-Raf, and to elucidate structural characteristics that influence the B-Raf kinase activity, molecular docking and three-dimensional quantitative structure-activity relationship（3D-QSAR） studies were performed on a dataset of 75 Type Ⅱ inhibitors. Molecular docking was applied to explore the detailed binding process between the inhibitors and B-Raf kinase in its DFG-out inactive conformation. Based on the conformations obtained by molecular docking strategy, 3D-QSAR models, including comparative molecular field analysis（CoMFA） and comparative molecular similarity indexes analysis（CoMSIA）, were constructed. The established 3D-QSAR models show significant statistical quality and satisfactory predictive ability, with high q^2 and r^2 values： CoMFA model（q^2= 0.759, r^2 = 0.922）, and CoMSIA model（q^2 = 0.685, r^2 = 0.945）. The systemic external validation indicated that both CoMFA and CoMSIA models were quite robust and possess high predictive abilities with r^2 pred values of 0.633 and 0.708, respectively. Several key structural features accounting for the inhibitory activities of these compounds were discussed based on the 3D contour maps generated by the CoMFA and CoMSIA models, which were in good accordance with the docking results. These theoretical results rendered by 3D-QSAR models along with the docking may provide a useful reference for understanding the action mechanism and designing novel potential B-Raf inhibitors.

CoMFA 3D-QSAR Analysis of Epothilones Based on Docking Conformation and Alignment

Epothilones belong to a class of novel microtubule stabilizing and anti-mitotic agents, which have a paclitaxel-like mechanism of action. A three-dimensional quantitative structure-activity relationship （3D-QSAR） model was built for epothilones by the method of comparative molecular field analysis （CoMFA） combined with the flexible docking technology. The docking CoMFA model gave a good cross-validated value of q2=0.784 with an optimized component of 6 and the conventional correlation coefficient of r^2=0.985. The statistical results show that the model has good ability to predict the activity of the studied compounds. At last, the docking CoMFA model was analyzed through contour maps complemented with MOLCAD-generated active site potential surface in the α,β-tubulin receptor, which can provide important information for the structure-based drug design.

Comprehensive 3D-QSAR and Binding Mode of DAPY Inhibitors Using R-group Search and Molecular Docking

The diarylpyrimidine(DAPY) compounds are important in the nonnucleoside reverse enzyme inhibitors. The present study is aimed at studying the three-dimensional quantitative structure-activity relationship(3D-QSAR) of DAPY inhibitors and their binding mode. We build a 3D-QSAR model involving 24 training DAPY inhibitors based on Topomer CoMFA, and 8 molecules are employed to validate the external predictive power of the model obtained. The multiple correlation coefficients of fitting, cross-validation and external validation were 0.979, 0.597 and 0.756, respectively. Topomer Search was employed as a tool for virtual screening in drug-like compounds of ZINC database(2012). Finally, we successfully design 30 new molecules with higher activity than that of all training and test inhibitors. The results indicated that Topomer CoMFA model had both favorable estimation stability and good predictive capability. Topomer Search technology could be effectively used to screen and design new compound, and had good predictive capability to guide the design of new Anti-HIV drugs. The molecular docking method was also used to study the interactions of these drugs by docking the ligands into HIV-1 reverse transcriptase active site, which revealed the likely bioactive conformations. This study showed extensive interactions between the DAPY derivatives and MET230, TRP229, PHE227, TYR318, TYR183, PRO95, GLY99, ILE100,TYR188, VAL106, TYR181, GLY190, GLU138, VAL179, THR139, ASN103 and LYS101 residues in the active site of HIV-1 reverse transcriptase. These results provide useful insights for the design of potent new inhibitors of HIV-1 reverse transcriptase.

Docking and 3D-QSAR Analysis on a Series of Pyridone-based EZH2 Inhibitors

Enhancer of Zeste homolog 2（EZH2） is closely correlated with malignant tumor and regarded as a promising target to treat B-cell lymphoma. In our research, the molecular docking and three-dimensional quantitative structure-activity relationships（3D-QSAR） studies were performed on a series of pyridone-based EZH2 compounds. Molecular docking allowed us to study the critical interactions at the binding site of EZH2 protein with inhibitors and identify the practical conformations of ligands in binding pocket. Moreover, the docking-based alignment was applied to derive the reliable 3D-QSAR models. Comparative molecular field analysis（CoMFA） and comparative molecular similarity indices analysis（CoMSIA） provided available ability of visualization. All the derived 3D-QSAR models were considered to be statistically significant with respect to the internal and external validation parameters. For the CoMFA model, q^2 = 0.649, r^2 = 0.961 and r^2 pred = 0.877. For the CoMSIA model, q^2 = 0.733, r^2 = 0.980 and r^2 pred = 0.848. With the above arguments, we extracted the correlation between the biological activity and structure. Based on the binding interaction and 3D contour maps, several new potential inhibitors with higher biological activity predicted were designed, which still awaited experimental validation. These theoretical conclusions could be helpful for further research and exploring potential EZH2 inhibitors.

A 3D-QSAR Study of HIV-1 Integrase Inhibitors Using RASMS and Topomer CoMFA

Acquired Immunodeficiency Syndrome(AIDS) is a significant human health threat around the world. Therefore, the study of anti-human immunodeficiency virus(HIV) drug design has become an important task for today’s society. In this paper, a three-dimensional quantitative structure-activity relationships study(3 D-QSAR) was conducted on 53 HIV-1 integrase inhibitors(IN) using random sampling analysis on molecular surface(RASMS) and Topomer comparative molecular field analysis(Topomer CoMFA). The multiple correlation coefficients of fitting, cross-validation, and external validation of two models were 0.926, 0.815 and 0.908 and 0.930, 0.726 and 0.855, respectively. The results indicated that two models obtained had both favorable estimation stability and good prediction capability. Topomer Search was used to search appropriate R groups from ZINC database, and 28 new compounds were designed thereby. The Topomer CoMFA model was subsequently used to predict the biological activity of these compounds, showing that 24 of the new compounds were more active than the template molecule. Ligands of the template molecule and new designed compounds were used for molecular docking to study the interaction of these compounds with the protein receptor. The results show that the ligands would form hydrogen-bonding interactions with the residues LEU58, THR83, GLN62, MET155, LYS119 and ALA154 of the protein receptor generally, thereby providing additional insights for the design of even more effective HIV/AIDS drugs.

Molecular Modeling Studies of 4-Hydroxyamino α-Pyranone Carboxamide Analogues as Hepatitis C Virus Inhibitor Using 3D-QSAR and Molecular Docking

In this paper, 42 4-hydroxyamino α-pyranone carboxamide analogues as Hepatitis C Virus(HCV) inhibitor 3 D-QSAR model was built based on Topomer CoMFA. The non-cross-validation(r2), cross-validation(q2), correlation coefficient of external validation(Q ext2), non-cross validated standard error(SD), standard error of prediction(SDCV) and F are 0.909, 0.615, 0.967, 0.13, 0.28 and 37.287, respectively. The obtained Topomer CoMFA model has good estimation stability and prediction capability. Topomer Search was employed as a tool for virtual screening in lead-like compounds in the ZINC database. Then, 6 R1 groups and 4 R2 groups with higher contribution values were employed to alternately substitute for the R1 and R2 of the template compound 21 with the highest bioactivity. As a result, 22 new molecules with higher activity than that of the template molecule were designed successfully. The Topomer Search technology could be effectively applied to screen and design new 4-hydroxyamino α-pyranone carboxamide analogues. The molecular docking method was also used to study the interactions of these drugs by docking the ligands into HCV active site, which revealed the likely bioactive conformations. This study showed extensive interactions between the 4-hydroxyamino α-pyranone carboxamide analogues and the active sites of HCV(residues TYR466, GLN384, TYR383 and ASP335). The design of potent new inhibitors of HCV can get useful insights from these results.

3D-QSAR Study on the Inhibitory Activity of Flavonoids on PIM-1 Kinase

20 Typical flavonoids were selected for study on the interaction between them and PIM-1 kinase with the comparative molecular field analysis method（CoMFA） as well as the comparative molecular similarity index analysis method（CoMSIA） based on molecule docking.3D-QSAR models between these flavonoids and receptor PIM-1 kinase were established.The obtained optimal cross-validation correlation coefficient Q2 for CoMFA model was 0.582,and the non-cross-validation correlation coefficient R2 was 0.955;the corresponding values for CoMSIA model were 0.790 and 0.974,respectively.These two models showed fairly fine stability and predictive ability.In addition,molecule docking results revealed the key residues in the receptor cavity and their specific action ways with flavonoids.