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Dihydropyrimidines are widely recognized for their diverse biological properties and are often synthesized by the Biginelli reactions. In this backdrop, a novel series of Biginelli dihydropyrimidines were designed, synthesized, purified, and analyzed by FT-IR, 1H NMR, 13C NMR, and mass spectrometry. Anticancer activity against MCF-7 breast cancer cells was evaluated as part of their cytotoxicity in comparison with the normal Vero cells. The cytotoxicity of dihydropyrimidines ranges from moderate to significant. Among the 38 dihydropyrimidines screened, compounds 16 , 21 , and 39 exhibited significant cytotoxicity. These 3 compounds were subjected to flow cytometry studies and EGFRwt Kinase inhibition assay using lapatinib as a standard. The study included evaluation for the inhibition of EGFR and HER2 expression at five different concentrations. At a concentration of 1000 nM compound 21 showed 98.51 % and 96.79 % inhibition of EGFR and HER2 expression. Moreover, compounds 16 , 21 and 39 significantly inhibited EGFRwt activity with IC 50 = 69.83, 37.21 and 76.79 nM, respectively. In addition, 3D-QSAR experiments were conducted to elucidate Structure activity relationships in a 3D grid space by comparing the experimental and predicted cytotoxic activities. Molecular docking studies were performed to validate the results by in silico method. All together, we developed a new series of Biginelli dihydropyrimidines as dual EGFR/HER2 inhibitors. [Display omitted] • Multicomponent reactions help to swiftly synthesize and evaluate molecules for activity. • This research covers synthesis of 38 dihydropyrimidines and their activity against EGFR/HER2. • Novel dihydropyrimidines can be potential anticancer therapeutics. • Synthesized dihydropyrimidines are quite effective against breast cancer target. • Computational studies have been performed as predictive analysis to correlate with experimental studies. [ABSTRACT FROM AUTHOR]

To understand the pharmacophore properties of 2-aminothiazoles and design novel inhibitors against the prion protein, a highly predictive 3D quantitative structure–activity relationship (QSAR) has been developed by performing comparative molecular field analysis (CoMFA) and comparative similarity analysis (CoMSIA). Both CoMFA and CoMSIA maps reveal the presence of the oxymethyl groups in meta and para positions on the phenyl ring of compound 17 (N-[4-(3,4-dimethoxyphenyl)-1,3-thiazol-2-yl]quinolin-2-amine), is necessary for activity while electro-negative nitrogen of quinoline is highly favorable to enhance activity. The blind docking results for these compounds show that the compound with quinoline binds with higher affinity than isoquinoline and naphthalene groups. Out of 150 novel compounds retrieved using finger print analysis by pharmacophoric model predicted based on five test sets of compounds, five compounds with diverse scaffolds were selected for biological evaluation as possible PrP inhibitors. Molecular docking combined with fluorescence quenching studies show that these compounds bind to pocket-D of SHaPrP near Trp145. The new antiprion compounds 3 and 6 , which bind with the interaction energies of −12.1 and −13.2 kcal/mol, respectively, show fluorescence quenching with binding constant ( K d ) values of 15.5 and 44.14 μM, respectively. Further fluorescence binding assays with compound 5 , which is similar to 2-aminothiazole as a positive control, also show that the molecule binds to the pocket-D with the binding constant ( K d ) value of 84.7 μM. Finally, both molecular docking and a fluorescence binding assay of noscapine as a negative control reveals the same binding site on the surface of pocket-A near a rigid loop between β2 and α2 interacting with Arg164. This high level of correlation between molecular docking and fluorescence quenching studies confirm that these five compounds are likely to act as inhibitors for prion propagation while noscapine might act as a prion accelerator from PrP C to PrP Sc . [ABSTRACT FROM AUTHOR]

A new series of new diphenylamine containing 1,2,4-triazoles were synthesized from 4-arylideneamino-5-[2-(2,6-dichlorophenylamino) benzyl]-2H-1,2,4-triazole-3(4H)-thiones 3a-f. The synthesized compounds were screened for in-vitro antimycobacterial and antibacterial activities. The synthesized compounds 4a, 4e and 4d have shown potential activity against Mycobacterium tuberculosis H37Rv strain with MIC of 0.2, 1.6 and 3.125 µM respectively. To investigate the SAR of diphenylamine containing 1,2,4-triazole derivatives in more details, CoMFA (q²-0.432, r²-0.902) and CoMSIA (q²-0.511, r²-0.953) models on M. tuberculosis H37Rv were established. The generated 3D-QSAR models are externally validated and have shown significant statistical results, and these models can be used for further rational design of novel diphenylamine containing 1,2,4-triazoles as potent antitubercular agents. [ABSTRACT FROM AUTHOR]

Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were applied to the ACE-inhibitory, antimicrobial, and bitter-tasting peptides. Predictive 3D-QSAR models were established using SYBYL multifit molecular alignment rule over a training set and a test set. The optimum models were all statistically significant with cross-validated coefficients (Q ²) >0.5 and conventional coefficients (R ²) >0.9, indicating that they were reliable enough for activity prediction. The obtained results may aid in the design of novel bioactive peptides. [ABSTRACT FROM AUTHOR]

Abstract: A series of symmetrical and unsymmetrical 1,4-dihydropyridines were synthesized by a rapid, single pot microwave irradiation (MWI) based protocol along with conventional approach and characterized by NMR, IR and mass spectroscopic techniques. The compounds were evaluated for their tumor cell cytotoxicity in HL-60 tumor cells. A 3D-QSAR study using CoMFA and CoMSIA was carried out to decipher the factors governing MDR reversing ability in cancer. The resulting contour maps derived by the best 3D-QSAR models provide a good insight into the molecular features relevant to the biological activity in this series of analogs. 3D contour maps as a result of 3D-QSAR were utilized to identify some novel features that can be incorporated into the 1,4-dihydropyridine framework to enhance the activity. [Copyright &y& Elsevier]

Abstract: In order to develop a lead antimycobacterium tuberculosis compound, a series of 52, novel pyrrole hydrazine derivatives have been synthesized and screened which target the essential enoyl-ACP reductase. The binding mode of the compounds at the active site of enoyl-ACP reductase was explored using surflex-docking method. The binding model suggests one or two hydrogen bonding interactions between pyrrole hydrazones and InhA enzyme. Highly active compound 5r (MIC 0.2 μg/mL) showed hydrogen bonding interactions with Tyr158 and NAD+ in the same manner as those of ligands PT70 and triclosan. The CoMFA and CoMSIA models generated with database alignment were the best in terms of overall statistics. The predictive ability of the CoMFA and CoMSIA models was determined using a test set of 13 compounds, which gave predictive correlation coefficients (r pred 2) of 0.896 and 0.930, respectively. [Copyright &y& Elsevier]

Abstract: A series of 2-hydrazinyl-4-morpholinothieno[3,2-d]pyrimidine derivatives were synthesized and evaluated for their cytotoxic activities against five cancer cell lines. Most of them exhibited moderate to significant cytotoxic activities and high-selectivity against one or more cell lines, and nearly all of them had higher potency than positive controls against MDA-MB-231 cell line. The most promising compound 15f showed strong cytotoxic activities against H460, HT-29 and MDA-MB-231 cell lines, which were 1.7- to 66.5-folds more active than 2-(1H-Indazol-4-yl)-6-((4-(methylsulfonyl)-1-piperazinyl)methyl)-4-(4-morpholinyl)thieno[3,2-d]pyrimidine(GDC-0941). To investigate the SARs of thieno[3,2-d]pyrimidine derivatives in more details, CoMFA (q 2 = 0.436, r 2 = 0.937) and CoMSIA (q 2 = 0.706, r 2 = 0.947) models on H460 cell line were established. The generated 3D-QSAR models can be used for further rational design of novel thienopyrimidines as highly potent and selective cytotoxic agents. [Copyright &y& Elsevier]

Abstract: CB2 receptor belongs to the large family of G-protein coupled receptors (GPCRs) controlling a wide variety of signal transduction. The recent crystallographic determination of human β2 adrenoreceptor and its high sequence similarity with human CB2 receptor (hCB2) prompted us to compute a theoretical model of hCB2 based also on β2 adrenoreceptor coordinates. This model has been employed to perform docking and molecular dynamic simulations on WIN-55,212-2 (CB2 agonist commonly used in binding experiments), in order to identify the putative CB2 receptor agonist binding site, followed by molecular docking studies on a series of indol-3-yl-tetramethylcyclopropyl ketone derivatives, a novel class of potent CB2 agonists. Successively, docking-based Comparative Molecular Fields Analysis (CoMFA) and Comparative Molecular Similarity Indices Analysis (CoMSIA) studies were also performed. The CoMSIA model resulted to be the more predictive, showing r ncv 2 = 0.96, r cv 2 = 0.713, SEE = 0.193, F = 125.223, and r 2 pred = 0.78. The obtained 3D-QSAR models allowed us to derive more complete guidelines for the design of new analogues with improved potency so as to synthesize new indoles showing high CB2 affinity. [Copyright &y& Elsevier]

Abstract: In order to explore the interactions between flavones and P-gp, in silico methodologies such as docking and 3D-QSAR were performed. CoMFA and CoMSIA analyses were done using ligand based and receptor guided alignment schemes. Validation statistics include leave-one-out cross-validated R 2 (q 2), internal prediction parameter by progressive scrambling (Q ∗2), external prediction with test set. They show that models derived from this study are quite robust. Ligand based CoMFA (q 2 = 0.747, Q ∗2 = 0.639, ) and CoMSIA model (q 2 = 0.810, Q ∗2 = 0.676, ) were developed using atom by atom matching. Receptor guided CoMFA (q 2 = 0.712, Q ∗2 = 0.497, ) and for CoMSIA (q 2 = 0.805, Q ∗2 = 0.589, ) models were developed by docking of highly active flavone into the proposed NBD (nucleotide binding domain) of P-gp. The 3D-QSAR models generated here predicted that hydrophobic and steric parameters are important for activity toward P-gp. Our studies indicate the important amino acid in NBD crucial for binding in accordance with the previous results. This site forms a hydrophobic site. Since flavonoids have potential without toxicity, we propose to inspect this hydrophobic site including Asn1043 and Asp1049 should be considered for future inhibitor design. [Copyright &y& Elsevier]

Abstract: Trichomonosis is a common sexually transmitted infectious disease linked to reproductive health complications. Recently, the benzimidazole nucleus has emerged as a promising scaffold to develop new trichomonicidal agents. Despite the fact that large amounts of experimental data have been accumulated over the past eight years, no quantitative studies have yet been reported on this class of compounds. In our effort to develop new antiparasitic benzimidazole derivatives, we report in this paper CoMFA and CoMSIA studies with an initial set of 70 benzimidazole derivatives with trichomonicidal activity. Four CoMFA models and eight CoMSIA models were generated; ten of these models had values of r 2 > 0.6 and q 2 > 0.5. The best CoMFA model had r 2 = 0.936 and q 2 = 0.634, and the best CoMSIA model had r 2 = 0.858 and q 2 = 0.642. These models were generated by using two conformer selection methodologies (minimum energy conformations and 3D similarity), and three charge types (Mulliken, Gasteiger-Hükel and electrostatic potential atomic charges). The putative active tautomers of 1H-benzimidazole derivatives were selected using 3D-QSAR calculations. All models were validated via an external test set with 13 molecules. The best models satisfied additional validation criteria. The contour maps generated show the most important features that a benzimidazole derivative should have for trichomonicidal activity; they also, suggest that substituents at the 2- and 6-positions are important in the generation of derivatives with strong activity. [Copyright &y& Elsevier]

Abstract: Prostrate cancer constitutes the second leading cause of cancer deaths in men in United States. Eunicellin-based diterpenoids are important bioactive marine natural products isolated from corals of alcyonaria species. The bioactivities of eunicellin diterpenes were correlated with their chemical structures. Recently eunicellin diterpenes from the Red Sea soft coral Cladiella pachyclados showed significant anti-migratory and anti-invasive activities against prostate cancer in wound-healing and Cultrex® invasion models. These results encouraged the semisynthetic and 3D-QSAR studies of this unique marine natural product class as possible hits for the control of metastatic prostate cancer. Ten new semisynthetic analogues of cladiellisin (1) were prepared. These include C-6 carbamoylation and ∆11−17 epoxidation. Carbamate analogues of 1 showed potent anti-migratory and anti-invasive activities against PC-3 cells. Comparative Molecular Field Analysis (CoMFA) and Comparative Molecular Similarity Indices Analysis (CoMSIA) were performed using SYBYL 8.1 program package to create a valid 3D-QSAR model to guide future design of potent eunicellin diterpenes cancer migration inhibitors. Eunicellin-based diterpenes are potential marine natural hits appropriate for optimization as inhibitors of metastatic prostate cancer. [Copyright &y& Elsevier]

Abstract: 3D-QSAR studies namely CoMFA, CoMFA region focusing and CoMSIA have been carried out on a series (36 compounds) of HIV-1 entry inhibitors. An alignment rule for the compounds was defined using Distill in SYBYL 7.3. Models were validated using a data set obtained by dividing the data set into a training set and test set using hierarchical clustering, based on the CoMFA fields and biological activities (pIC50). The best predictions were obtained with a CoMFA region-focusing model (q2 = 0.719, rpred 2 = 0.911), CoMFA standard model (q2 = 0.660, rpred 2 = 0.890), and CoMSIA (steric and hydrophobic) model (q2 = 0.521, rpred 2 = 0.794). The statistical parameters from the models indicate that the data are well fitted and have high predictive ability. Moreover, the resulting 3D CoMFA/CoMSIA contour maps provide useful guidance for designing highly active inhibitors. [ABSTRACT FROM AUTHOR]

Abstract: Comparative molecular similarity indices analysis (CoMSIA) and comparative molecular field analysis (CoMFA) were performed on a series of bicyclo [4.1.0] heptanes derivatives as melanin-concentrating hormone receptor R1 antagonists (MCHR1 antagonists). Molecular superimposition of antagonists on the template structure was performed by database alignment method. The statistically significant model was established on sixty five molecules, which were validated by a test set of ten molecules. The CoMSIA model yielded the best predictive model with a q 2 = 0.639, non cross-validated R 2 of 0.953, F value of 92.802, bootstrapped R 2 of 0.971, standard error of prediction = 0.402, and standard error of estimate = 0.146 while the CoMFA model yielded a q 2 = 0.680, non cross-validated R 2 of 0.922, F value of 114.351, bootstrapped R 2 of 0.925, standard error of prediction = 0.364, and standard error of estimate = 0.180. CoMFA analysis maps were employed for generating a pseudo cavity for LeapFrog calculation. The contour maps obtained from 3D-QSAR studies were appraised for activity trends for the molecules analyzed. The results show the variability of steric and electrostatic contributions that determine the activity of the MCHR1 antagonist, with these results we proposed new antagonists that may be more potent than previously reported, these novel antagonists were designed from the addition of highly electronegative groups in the substituent di(i-C3H7)N– of the bicycle [4.1.0] heptanes, using the model CoMFA which also was used for the molecular design using the technique LeapFrog. The data generated from the present study will further help to design novel, potent, and selective MCHR1 antagonists. [Copyright &y& Elsevier]

Abstract: Aromatase inhibition is an attractive strategy for the treatment of hormone-dependent breast cancer. Quantitative structure activity relationship (QSAR) and pharmacophore space modeling studies are performed on benzcyclo- pentane/hexane derivatives to generate statistically significant models. Linear free energy QSAR model (R 2 = 0.874, Q 2 = 0.824, ) showed the importance of hydrophobicity and atomic charge functionality of the molecule for the activity. 3D QSAR models generated with molecular field (CoMFA, R 2 = 0.973, Q 2 = 0.702, ) and similarity analysis (CoMSIA, R 2 = 0.976, Q 2 = 0.803, ) studies indicated the importance of electrostatic and steric fields along with hydrophobicity of the molecule as important features for inhibiting aromatase enzyme. Further pharmacophore space modeling study (Q 2 = 0.845, ) confirmed that molecular hydrophobicity plays key role for aromatase inhibition. The structure–function characterization is adjudged in the active site of the target (3EQM). [ABSTRACT FROM AUTHOR]

Abstract: The marine-derived macrolide latrunculins A and B, from the Red Sea sponge Negombata magnifica, are known to reversibly bind actin monomers, forming 1:1 complex with G-actin, disrupting its polymerization. Latrunculins have remarkable physiological properties and widely used as biochemical markers. Nevertheless, no QSAR studies have been developed for any kind of actin disruptors. In the present study, Comparative Molecular Field Analysis (CoMFA) and Comparative Molecular Similarity Indices Analysis (CoMSIA) implemented in the SYBYL software packages were used to develop predictive 3D-QSAR models. Two alignment strategies were used to fit analyzed molecules to a suitable conformational template. By means of the SYBYL multifit alignment function, the best CoMFA and CoMSIA results presented cross-validated correlation coefficient values (q 2) of 0.621 and 0.659, and non-cross-validated values (r 2) of 0.938and 0.965, respectively. Comparable to multifit-derived models, CoMFA and CoMSIA 3D-QSAR models were also derived using a molecular alignment obtained by docking latrunculin derivatives into the ATP active site of actin. In addition to q 2, the predictive ability was validated using external test set of five compounds. The results of this study suggest that the established model has a strong predictive ability and can be prospectively used in the molecular design and action mechanism analysis of this kind of cytotoxic compounds. [ABSTRACT FROM AUTHOR]

Abstract: A series of quionolone caroxylic acid derivatives inhibitors of HIV-1 integrase were subjected to three-dimensional quantitative structure–activity relationship (3D-QSAR) studies using the comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) approaches. The CoMFA model includes steric and electrostatic fields for the training set with the cross-validated q 2 value of 0.67 and the non-cross-validated r 2 value of 0.98. The cross-validated q 2 value of CoMSIA Model is 0.76 and the non-cross-vaildated r 2 value is 0.99. From the cross-validated results, it can be seen that the CoMSIA model has a better predictive ability than CoMFA model. Based on the above results, the CoMFA and CoMSIA analyses can be used in the design of more potent HIV-1 integrase inhibitors. [Copyright &y& Elsevier]

Abstract: Rho kinase (ROCK) has become an attractive target for the treatment of many diseases such as hypertension, stroke and cancer. In this work, molecular docking and three-dimensional quantitative structure–activity relationship (3D-QSAR) studies were performed on a series of ROCK inhibitors. Molecular docking was used to explore the binding mode between the ligands and the receptor. Based on the docked conformations, comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were performed to gain insights into the key structural factors affecting the activity. The results of the molecular modeling studies suggested that further modification of these inhibitors with bulky and hydrophobic groups that accommodated in the distal region of the ROCK binding pocket would improve the activity. [Copyright &y& Elsevier]

Abstract: A series of human immunodeficiency virus type 1 (HIV-1) attachment inhibitors were subjected to ligand-based three-dimensional quantitative structure–activity relationship (3D-QSAR) studies using the comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) approaches. The CoMFA model yielded satisfactory statistical data with the cross-validated q 2 value of 0.589 and the non-cross-validated r 2 value of 0.963. The cross-validated q 2 value of CoMSIA Model was 0.621 and the non-cross-validated r 2 value was 0.972. From the cross-validated results, it can be seen that the CoMSIA model has a better predictive ability than CoMFA model. Based on the above results, the CoMFA and CoMSIA analyses can be used in the design of more potent HIV-1 attachment inhibitors. [Copyright &y& Elsevier]

Abstract: Computational chemistry is playing an increasingly important role in drug design and discovery, structural biology, and quantitative structure–activity relationship (QSAR) studies. For QSAR work, selecting an appropriate and accurate method to assign the electrostatic potentials of each atom in a molecule is a critical first step. So far several commonly used methods are available to assign charges. However, no systematic comparison of the effects of electrostatic potentials on QSAR quality has been made. In this study, twelve semi-empirical and empirical charge-assigning methods, AM1, AM1-BCC, CFF, Del-Re, Formal, Gasteiger, Gasteiger–Hückel, Hückel, MMFF, PRODRG, Pullman, and VC2003 charges, have been compared for their performances in CoMFA and CoMSIA modeling using several standard datasets. Some charge assignment models, such as Del-Re, PRODRG, and Pullman, are limited to specific atom and bond types, and, therefore, were excluded from this study. Among the remaining nine methods, the Gasteiger–Hückel charge, though commonly used, performed poorly in prediction accuracy. The AM1-BCC method was better than most charge-assigning methods based on prediction accuracy, though it was not successful in yielding overall higher cross-validation correlation coefficient (q 2) values than others. The CFF charge model worked the best in prediction accuracy when q 2 was used as the evaluation criterion. The results presented should help the selection of electrostatic potential models in CoMFA and CoMSIA studies. [Copyright &y& Elsevier]

Abstract: Thymidylate synthase (TS) is a crucial enzyme for DNA biosynthesis and many nonclassical lipophilic antifolates targeting this enzyme are quite efficient and encouraging as antitumor drugs. Herein, we report some 3D-QSAR analyses using CoMFA and CoMSIA on quinozoline antifolates in order to have a better understanding of the mechanism of action and structure-activity relationship of these compounds. By applying leave-one-out (LOO) cross-validation study, we obtained cross-validated q 2 value of 0.573 for CoMFA and 0.445 for CoMSIA, while the non-cross-validated r 2 values for them were found to be 0.935 and 0.893, respectively. The models were graphically interpreted using CoMFA and CoMSIA contour plots. The results obtained from this study could be used for rational design of potent inhibitors against thymidylate synthase. [Copyright &y& Elsevier]

Abstract: Aberrant regulation of cap-dependent translation has been frequently observed in the development of cancer. Association of the cap-binding protein eIF4E with N7-methylated guanosine capped mRNA is the rate limiting step governing translation initiation; and therefore represents an attractive process for cancer drug discovery. Previously, replacement of the 7-Me group of the Me7-guanosine monophosphate with a benzyl group has been found to increase binding affinity to eIF4E. Recent X-ray crystallographic studies have revealed that the cap-binding pocket undergoes a unique structural change in order to accommodate the benzyl group. To explore the structure-activity relationships governing the affinity of N7 -benzylated guanosine monophosphate (Bn7-GMP) for eIF4E, we virtually screened a library of 80 Bn7-GMP analogs utilizing CombiGlide as implemented in Schrodinger®. A subset library of substituted Bn7-GMP analogs was synthesized and their dissociation constants (Kd ) were determined. Due to the poor correlation between docking/scoring results and experimental binding affinities, three-dimensional quantitative structure-activity relationship (3D-QSAR) calculations were performed. Two highly predictive and self-consistent CoMFA (comparative molecular field analysis) and CoMSIA (comparative molecular similarity indices analysis) models were derived and optimized. These models may be useful for the future design of eIF4E cap-binding antagonists. [Copyright &y& Elsevier]

Abstract: Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were performed on 64 ketoamides as human cathepsin K (CatK) inhibitors, using ROCS ligand-based alignment and receptor-based alignment. Results generated from the ligand-based model were found to be superior to those obtained by the receptor-based model. CoMFA and CoMSIA field distributions are in good agreement with the structural characteristics of the binding groove of CatK, suggesting moderate substitutes at the P1, P2, P3 and P1′ may favor the inhibitory activity of ketoamides. These results provide useful information in understanding the structural and chemical features of CatK in designing and finding novel potential CatK inhibitors as osteoporosis therapeutic agents. [Copyright &y& Elsevier]

Abstract: Trichothecene mycotoxins, toxic natural products of fungi from the family Hypocreaceae, are potent inhibitors of protein synthesis. The application of 3D QSAR to these toxins explored the structural basis for their biological activities. A CoMFA (Q 2 =0.619, R 2 =0.921) model was developed for a set of 15 toxins with the trichothecene nucleus; CoMFA (Q 2 =0.518, R 2 =0.855) and CoMSIA (Q 2 =0.695, R 2 =0.960) models were developed for 31 toxins with the nucleus and a macrolide ring. The results show the role of electrostatics and steric factors in the activity of the toxins and indicate that the conformation of the macrolide ring influences the toxicity of the macrolide toxins. [Copyright &y& Elsevier]

Abstract: In this study, 3-aroyl-1,1-dioxo-1,4,2-benzodithiazine and 4-chloro-N-(4-oxopyrimidin-2-yl)-2-mercaptobenzenesulfonamide derivatives (HIV-1 integrase inhibitors) were used for CoMFA and CoMSIA to determine the substructures required for the activity of these molecules. To explore the binding mode of inhibitors, docking studies were done and docked conformation of highly active molecule was used as template for alignment. The best CoMFA model yielded the cross validation r 2 cv =0.728, non-cross validation r 2 ncv =0.934 and predictive r 2 pred =0.708. The best CoMSIA model yielded a cross validation r 2 cv =0.794, non-cross validation r 2 ncv =0.928 and predictive r 2 pred =0.59. It was found that steric (CoMFA) and hydrophobic fields (CoMSIA) have large contribution towards the inhibitory activity than the other fields. Docking and 3D-QSAR studies have provided clues to a better understanding of interaction between the inhibitors and HIV-1 integrase. [Copyright &y& Elsevier]

Abstract: Farnesyltransferase is a potential drug target for treating various types of cancers. Three-dimensional quantitative structure–activity relationships (3D-QSAR) for a series of farnesyltransferase inhibitors were investigated using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) techniques. Pharmacophore search and molecular docking methods were used for construction of the molecular alignments. While the 3D-QSAR models were created for a training set of 33 compounds, their external predictivity was proven using a test set of 12 compounds. The results provided a comprehensive insight into the relationship between the structural features and the activities of farnesyltransferase inhibitors. This investigation will facilitate optimization of the design of new potential farnesyltransferase inhibitors. [Copyright &y& Elsevier]

Abstract: Novel Biginelli dihydropyrimidines of biological interest were prepared using p-toluene sulphonic acid as an efficient catalyst. All the thirty-two synthesised dihydropyrimidines were evaluated for their in vitro antioxidant activity using DPPH method. Only, compounds 28 and 29 exhibited reasonably good antioxidant activity. Furthermore, the synthesised Biginelli compounds were subjected for their in vitro anticancer activity against MCF-7 human breast cancer cells. The title compounds were tested at the concentration of 10μg. Compounds exhibited activity ranging from weak to moderate and, from moderate to high in terms of percentage cytotoxicity. Among them, compounds 10 and 11 exhibited significant anticancer activity. In order to elucidate the three-dimensional structure–activity relationships (3D QSAR) towards their anticancer activity, we subjected them for comparative molecular similarity indices analysis (CoMSIA). Illustration regarding their synthesis, analysis, antioxidant activity, anticancer activity and 3D QSAR study is described. [Copyright &y& Elsevier]

Abstract: For the first time, a set of renin inhibitors were subjected to the 3D QSAR/CoMFA and CoMSIA studies. The utility of renin inhibitors in the treatment of cardiovascular diseases has not been fully explored yet. At the moment, aliskiren is the first and only existing renin inhibitor in the drug market. The performed 3D QSAR/CoMFA and CoMSIA in combination with docking studies included aliskiren and 37 derivatives possessing a wide variety of bioactivity. The obtained results may aid in the design of novel bioactive renin inhibitors. [Copyright &y& Elsevier]

Abstract: BMS-378806 (BMS-806) is a small molecule that blocks the binding of host-cell CD4 with viral gp120 protein and therefore inhibits the first steps of HIV-1 infection. Recently, 36 analogs compounds of BMS-806 were synthesized and their biological activity evaluated. Based on these compounds, a molecular docking was firstly performed with BMS-806 to the gp120 cavity in order to get a representative ligand conformation for the 3D-QSAR process. Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were then conducted for these 36 compounds. CoMFA and CoMSIA models give reliable correlative and predictive abilities but the CoMFA model performance was slightly better than CoMSIA. CoMFA contours were analysed and have been correlated to the gp120 viral protein. The discussion indicates several key fragment positions on the ligands and their implications on the gp120 protein binding. The computational approach used in this paper provides reliable clues for further design of small molecules gp120/CD4 inhibitors based on the BMS-806. [Copyright &y& Elsevier]

Abstract: RA-VII, a bicyclic hexapeptide isolated from the roots of Rubia cordifolia, Rubia akane belongs to Rubiaceae-type cyclopeptides (RAs) and has attracted much attention for its potent anti-tumor activity and its bicyclic structure incorporating the isodityrosine moiety. In this work, hologram quantitative structure–activity relationship (HQSAR), comparative molecular field analysis (CoMFA), and comparative molecular similarity indices analysis (CoMSIA) methods were employed to develop 2D- and 3D-QSAR models for 54 anti-tumor RAs. The LOO cross-validated q2 values of HQSAR, CoMFA and CoMSIA models are 0.701, 0.510 and 0.613, respectively. The predictive ability of these models was validated by the test set including 7 RAs, and the predicted IC50 values were in good agreement with the experimental IC50 values. HQSAR result showed that chirality descriptor plays an important role in anti-tumor activity of RAs and OMe at R1 and R2 is necessary for increasing their activity. CoMFA and CoMSIA results demonstrated that small bulky and electropositive side chains at R3 position and hydrophobic groups at R7 and R8 positions will increase their activity, and intra-molecular hydrogen bonds between residues 1 and 4 are necessary to maintain the pharmacophoric conformation of RAs. These results may be helpful in designing novel and potential anti-tumor RAs. [Copyright &y& Elsevier]

Abstract: This paper describes CoMFA and CoMSIA studies for affinity and selectivity of a series of indole ligands to cannabinoid CB1 and CB2 receptors. The developed models have proven to be predictive, with average q 2 of 0.675 and average r 2 of 0.855, demonstrating a good statistical validation. The obtained results have helped us to understand the structural motifs that are responsible for the affinity and selectivity of some of these derivatives towards each subtype of cannabinoid receptor and have demonstrated that the exploited 3D-QSAR methods could be useful tools for the design of new safer analogues presenting better affinity and selectivity profiles. [Copyright &y& Elsevier]

Abstract: Thiocarbamates (TCs) have been recently identified as a new class of potent non-nucleoside HIV-1 Reverse Transcriptase (RT) inhibitors. A computational strategy based on molecular docking studies, followed by CoMFA and CoMSIA analyses, has been used to elucidate the atomic details of the RT/TC interactions and to identify the most important features impacting the TC antiretroviral activity. The CoMFA model resulted to be the more predictive, and gave r 2 =0.93, r cv 2 =0.53, SEE=0.292, F =180, and r test 2 =0.70. The 3D-QSAR field contributions and the structural features of the RT binding site showed a good correlation. These studies will be useful to design new TCs with improved potency also against clinically relevant resistant mutants. [Copyright &y& Elsevier]

Abstract: Three-dimensional quantitative structure–activity relationship (3D-QSAR) studies were performed for a series of dipeptide boronate proteasome inhibitors using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) techniques. A training set containing 46 molecules served to establish the models. The optimum CoMFA and CoMSIA models obtained for the training set were all statistically significant with cross-validated coefficients (q 2) of 0.676 and 0.630 and conventional coefficients (r 2) of 0.989 and 0.956, respectively. The predictive capacities of both models were successfully validated by calculating a test set of 13 molecules that were not included in the training set. The predicted correlation coefficients (r 2 pred) of CoMFA and CoMSIA are 0.963 and 0.919, respectively. The CoMFA and CoMSIA field contour maps agree well with the structural characteristics of the binding pocket of β5 subunit of 20S proteasome, which suggests that the 3D-QSAR models constructed in this paper can be used to guide the development of novel dipeptide boronate inhibitors of 20S proteasome. [Copyright &y& Elsevier]

Abstract: HIV-1 (human immunodeficiency virus type-1) is the pathogenic retrovirus and causative agent of AIDS. HIV-1 RT is one of the key enzymes in the duplication of HIV-1. Inhibitors of HIV-1 RT are classified as NNRTIs and NRTIs. NNRTIs bind to a region that is not associated with the active site of the enzyme. Within the NNRTIs category, there is a set of inhibitors commonly referred to as thiazolidinone derivatives. The present 3D-QSAR study attempts to explore the structural requirements of thiazolidinone derivatives for anti-HIV activity. Based on the structures and biodata of previous thiazolidinone analogs, 3D-QSAR studies have been performed with a training set consisting of 96 molecules, which resulted in two reliable computational models, CoMFA and CoMSIA with r 2 values of 0.931 and 0.972, standard error of estimation (SEE) of 0.173 and 0.089, and q 2 values of 0.663 and 0.784, respectively, with the number of partial least-squares (PLS) components being six. It is shown that the steric and electrostatic properties predicted by CoMFA contours and the hydrogen bond acceptor, hydrogen bond donor, and hydrophobic properties predicted by CoMSIA contours are related to anti-HIV activity. The predictive ability of the resultant model was evaluated using a test set comprising of 17 molecules and the predicted r 2 values of CoMFA and CoMSIA models were 0.861 and 0.958, respectively. These models are more significant guide to trace the features that really matter especially with respect to the design of novel compounds. [Copyright &y& Elsevier]

Abstracts: A combined physicochemical and 3D technique is used to establish the QSAR of four series of non-benzodiazepines towards BzR. In physicochemical QSAR study, the semi-empirical PM3 based parameters like hardness, electronegativity, electrophilicity index, molar refractivity, heat of formation, solvent assessable surface area and log P were used as descriptors. The heat of formation (HF) and log P are recognized as the most important descriptors for binding affinity of such compounds to BzR. The 3D QSAR study reveals that β-Carbolines of series “A” and Imidazo[1, 2-α]pyrimidines of series “C” show steric bulk interaction, the β-Carbolines of series “B” and di-substituted purines of series “D” have dominance of electrostatic interaction with BzR. The CoMSIA also indicate the same trend in terms of steric and electrostatic interaction. The CoMSIA reveals that only in case of series “D”, the hydrophobic field effect is important. Some possible candidates for all four series were designed and their probable activities were estimated by using different QSAR models. The activities of designed molecules are in better range and developed models might be helpful to design the potent ligands of BzR. [Copyright &y& Elsevier]

Abstract: Multi-drug resistance to commonly used antitubercular drugs has propelled the development of new structural classes of antitubercular agents. This paper reports the synthesis, evaluation and 3D-QSAR analysis of a set of substituted N-phenyl-6-methyl-2-oxo-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carboxamides as antitubercular agents. Substituted acetoacetanilides were reacted with various aromatic aldehydes and urea which yielded the tetrahydropyrimidine derivatives with a phenyl carbamoyl group at C5 position, and with various substitutions on the 4-phenyl and the N-phenyl aromatic rings. All compounds were screened for antitubercular activity against Mycobacterium tuberculosis H37Rv strain. The QSAR models were generated on a training set of 23 molecules. The molecules were aligned using the atom-fit and field-fit techniques. The CoMFA and CoMSIA models generated on the molecules aligned by the atom-fit method show a correlation coefficient (r 2) of 0.98 and 0.95 with cross-validated r 2(q 2) of 0.68 and 0.58, respectively. The 3D-QSAR models were externally validated against a test set of 7 molecules for which the predictive r 2 () is recorded as 0.41 and 0.32 for the CoMFA and CoMSIA models, respectively. The CoMFA and CoMSIA contours helped to design some new molecules with improved activity. [Copyright &y& Elsevier]

Abstract: Three-dimensional quantitative structure-activity relationship (3D-QSAR) studies were performed on 97 4-phenylpyrrolo[3,4-c]carbazole-1,3(2H,6H)-dione inhibitors, based on molecular docking scores obtained by using GOLD 3.1, comparative molecular field analysis (CoMFA) and comparative molecular similarity indices (CoMSIA). The docking results provided a reliable conformational alignment scheme for the 3D-QSAR model. Based on the docking conformations and alignments, highly predictive CoMFA and CoMSIA were obtained with cross-validated q 2 value of 0.828 and 0.796, respectively, and non-cross-validated partial least-squares (PLS) analysis with the optimum components of five showed a conventional r 2 of 0.962 and 0.949, respectively. The predictive ability was validated by compounds that were not included in the training set. Furthermore, the CoMFA and CoMSIA model plots were mapped back to the binding sites of Checkpoint Kinase Weel, to get a better understanding of vital interactions between the inhibitors and Weel kinase. As a result, we have identified some key features in the 4-phenylpyrrolo[3,4-c]carbazole-1,3(2H,6H)-diones responsible for the Weel inhibitory activity that may be used to design more potent 4-phenylpyrrolo[3,4-c]carbazole-1,3(2H,6H)-diones and predict their activity prior to synthesis. [Copyright &y& Elsevier]

Abstract: A three-dimensional quantitative structure–activity relationship (3D-QSAR) study was performed on three different chemical series reported as selective farnesyltransferase (FTase) inhibitors employing comparative molecular field analysis (CoMFA) and comparative molecular similarity indices (CoMSIA) techniques to investigate the structural requirements for substrates and derive a predictive model that may be used for the design of novel FTase inhibitors. Removal of outliers improved the predictive power of models developed for all three structurally diverse classes of compounds. 3D-QSAR models were derived for 3-aminopyrrolidinone derivatives (training set N =38, test set N =7), 2-amino-nicotinonitriles (training set N =46, test set N =13) and 1-aryl-1′-imidazolyl methyl ethers (training set N =35, test set N =5). The CoMFA models with steric and electrostatic fields exhibited r 2 cv 0.479–0.803, r 2 ncv 0.945–0.993, r 2 pred 0.686–0.811. The CoMSIA models displayed r 2 cv 0.411–0.814, r 2 ncv 0.923–0.984, r 2 pred 0.399–0.787. 3D contour maps generated from these models were analyzed individually, which provide the regions in space where interactive fields may influence the activity. The superimposition of contour maps on the active site of farnesyltransferase additionally helps in understanding the structural requirements of these inhibitors. 3D-QSAR models developed may guide our efforts in designing and predicting the FTase inhibitory activity of novel molecules. [Copyright &y& Elsevier]

Abstract: Structure-based 3D-QSAR studies were performed on a series of novel heteroarylpiperazine derivatives as 5-HT3 receptor antagonists with comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) methods. The compounds were initially docked into the binding pocket of the homology model of 5-HT3 receptor using GOLD program. The docked conformations with the highest score were then extracted and used to build the 3D-QSAR models, with cross-validated values 0.716 and 0.762 for CoMFA and CoMSIA, respectively. The CoMFA and CoMSIA contour plots were also fitted into the 3D structural model of the receptor to identify the key interactions between them, which might be helpful for designing new potent 5-HT3 receptor antagonists. [Copyright &y& Elsevier]

Abstract: Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA), three-dimensional quantitative structure–activity relationship (3D-QSAR) techniques, were applied to a set of 89 HIV-1 integrase (IN) inhibitors (training set=61, test set=28), belonging to 11 structurally different classes. The biological data for 3′ processing mechanism were used. For CoMFA calculations, three different fitting methods for alignment process were investigated. The best CoMFA model yielded the cross-validated r 2 (r cv 2)=0.698 and the non-cross-validated r 2 (r 2)=0.947. The derived model indicated the importance of steric (60.8%) as well as electrostatic (39.2%) contributions. For CoMSIA calculations, different combinations of the fields were tested. The best CoMSIA model gave r cv 2 =0.724 and r 2 =0.864. This model showed that steric (30.3%), hydrogen bond donor (43.4%) and hydrogen bond acceptor (26.3%) properties played major roles in HIV-1 IN inhibition. The mapping of hydrogen bond interaction fields with the HIV-1 IN active site gave details on hydrogen bond forming between ligands and enzyme. These obtained results agree well with the experimental observations that there should be hydrogen bond interactions between ligands and Glu152, Lys156 and Lys159 residues. The results not only lead to a better understanding of structural requirements of HIV-1 IN inhibitors but also can help in the design of new IN inhibitors. [Copyright &y& Elsevier]

Abstract: 3D-QSAR studies of some tricyclicpiperazinyl derivatives as farnesyltransferase inhibitors were performed by comparative molecular field analysis (CoMFA) and comparative molecular similarity indices (CoMSIA) methods to rationalize the structural requirements responsible for the inhibitory activity of these compounds. The global minimum energy conformer of the template molecule 35, the most active and pharmacokinetically stable molecule of the series, was obtained by simulated annealing method and used to build structures of the molecules in the dataset. The CoMFA model obtained after the removal of outliers produced statistically significant results with cross-validated and conventional correlation coefficients of 0.550 and 0.969, respectively. The combination of steric, electrostatic, hydrogen bond acceptor and hydrophobic fields in CoMSIA gave the best results with cross-validated and conventional correlation coefficients of 0.611 and 0.986, respectively. The predictive ability of CoMFA and CoMSIA were determined using a test set of 24 tricyclicpiperazinyl derivatives giving predictive correlation coefficients of 0.543 and 0.663, respectively, indicating good predictive power. Further the robustness of the model was verified by bootstrapping analysis. Based on the CoMFA and CoMSIA analysis we have identified some key features in the tricyclicpiperazinyl series that are responsible for farnesyltransferase inhibitory activity that may be used to design more potent tricyclicpiperazinyl derivatives and predict their activity prior to synthesis. [Copyright &y& Elsevier]

Abstract: Glycogen synthase kinase 3 (GSK-3) plays an important role in a diverse number of regulatory pathways by phosphorylation of several different cellular targets and its inhibitors have been evaluated as promising drug candidates. Indirubin analogues show favorable inhibitory activity targeting GSK-3β, which is closely related to the property and position of substituents. Two methods were used to build 3D-QSAR models for indirubin derivatives. The conventional 3D-QSAR (ligand-based) studies were performed based on the lower energy conformations employing atom fit alignment rule. The receptor-based 3D-QSAR models were also derived using bioactive conformations obtained by docking the compounds to the active site of GSK-3. Conclusions of models based on two methods are similar and reliable. The results indicate that both ligand-based and receptor-based are feasible tools to build 3D-QSAR models. Contour maps of the receptor-based CoMSIA model (q 2 =0.766, r 2 = 0.908, N (number of components)=5) including the steric, electronic and hydrophobic fields were taken as representative to explain factors affecting activities of inhibitors. [Copyright &y& Elsevier]

The 3D QSAR analyses of antimalarial alkoxylated and hydroxylated chalcones were first conducted by Comparative molecular field analysis (CoMFA) and Comparative similarity indices analysis (CoMSIA) to determine the factors required for the activity of these compounds. Satisfactory results were obtained after performing a leave-one-out (LOO) cross-validation study with cross-validation q2 and conventional r2 values of 0.740 and 0.972 by the CoMFA model, 0.714 and 0.976 by the CoMSIA model, respectively. The results provided the tools for predicting the affinity of related compounds, and for guiding the design and synthesis of novel and more potent antimalarial agents. [Copyright &y& Elsevier]

The 3D-QSAR studies of some indole derivatives as phosphodiesterase (PDE) type IV inhibitors was performed by Comparative Molecular Field Analysis (CoMFA) and Comparative Molecular Similarity Indices Analysis (CoMSIA) methods to determine the factors required for the activity of these compounds. The global minimum energy conformer of the template molecule, 3 the most active molecule of the series, was obtained by simulated annealing method and used to build the structures of the molecules in the dataset. The CoMFA model produced statistically significant results with cross-validated and conventional correlation coefficients of 0.494 and 0.986 respectively. The combination of steric, electrostatic and hydrophobic fields in CoMSIA gave the best results with cross-validated and conventional correlation coefficients of 0.541 and 0.967 respectively. The predictive ability of CoMFA and CoMSIA were determined using a test set of seven indole derivatives giving predictive correlation coefficients of 0.56 and 0.59 respectively indicating good predictive power. Further, the robustness of the models was verified by bootstrapping analysis. Based upon the information derived from CoMFA and CoMSIA, we have identified some key features that may be used to design new indole derivatives and predict their PDE IV affinities prior to synthesis. [Copyright &y& Elsevier]

A series of hydrazones of 1,2-benzisothiazole hydrazides 1a–m, 2a–m, 3a–m, 4a–m, 5a–m as well as their cyclic (1 and 4) and acyclic (2, 3 and 5) 1,2-benzisothiazole parent hydrazides, were synthesised and evaluated as antibacterial and antifungal agents. All of the 2-amino-1,2-benzisothiazol-3(2H)-one derivatives, belonging to series I and IV, showed a good antibacterial activity against Gram positive bacteria. Most of them were active against yeasts too. Compounds 1 and 4, together with 1l, proved to be the most effective compounds. Quantitative structure-activity relationship (QSAR) investigation with a 2D-QSAR analysis was applied to find a correlation between different experimental or calculated physicochemical parameters of the compounds studied. A 3D-QSAR study was performed, applying Comparative Molecular Similarity Indices Analysis (CoMSIA) method, to derive quantitative models relating the structural features of 1,2-benzisothiazole derivatives 1, 1a–m and 4, 4a–m and their antimicrobial activity against Bacillus subtilis, resulted the most sensitive micro-organism. [ABSTRACT FROM AUTHOR]

Four series of thiopyranopyrimidine AZD9291 derivatives containing acrylamide structure were designed, synthesized and evaluated for their antiproliferative activity against A549 and Hela cancer cells. Most of the compounds exhibited excellent antiproliferative activity against A549 cells. Moreover, the compounds with indole ring fluorine substituted exhibited better antiproliferative activity against Hela cells. The most promising compound 23g exhibited excellent enzymatic inhibitory activity and selectivity for EGFRL858R/T790M double mutations. The IC 50 value against EGFRL858R/T790M kinase was 16 nM. The compound 23g inhibits selectively against the mutated form of EGFR, with the selectivity more than 125-fold. Furthermore, compound 23g also inhibited A549 cells, Hela cells and H1975 cells proliferation at a low concentration, and the IC 50 values were 0.057 μM, 0.104 μM and 0.916 μM, respectively. To further investigate the QSARs of thiopyranopyrimidine derivatives, the CoMFA (q [2] = 0.765, r2 = 0.965) and CoMSIA (q [2] = 0.875, r2 = 0.956) models on Hela cancer cells were established. The generated 3D-QSAR model was validated to be reliable and can be used for further design and optimization of novel and selective EGFR inhibitors. Four series of AZ9291 derivatives bearing thiopyranopyrimidine structure were designed, synthesized. The potent compound 23g exhibited more than 125-fold selectivity against EGFRL858R/T790M double mutations. Furthermore, compound 23g also inhibited A549 cells, Hela cells and H1975 cells proliferation at a low concentration, and the IC 50 values were 0.057 μM, 0.104 μM and 0.916 μM, respectively. Image 1 • Four series of potent and selective EGFRL858R/T790M inhibitors were designed and characterized. • The selectivity of 23g against wild-type EGFR was near to 125-fold. • 20g inhibited A549, Hela and H1975 cells proliferation, and the IC 50 values were 0.057 μM, 0.104 μM and 0.916 μM, respectively. • 3D-QSAR analysis employed by CoMFA and CoMSIA model on Hela cell line was investigated. [ABSTRACT FROM AUTHOR]

Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were applied to the ACE-inhibitory, antimicrobial, and bitter-tasting peptides. Predictive 3D-QSAR models were established using SYBYL multifit molecular alignment rule over a training set and a test set. The optimum models were all statistically significant with cross-validated coefficients (Q(2)) >0.5 and conventional coefficients (R(2)) >0.9, indicating that they were reliable enough for activity prediction. The obtained results may aid in the design of novel bioactive peptides., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Aberrant regulation of cap-dependent translation has been frequently observed in the development of cancer. Association of the cap-binding protein eIF4E with N(7)-methylated guanosine capped mRNA is the rate limiting step governing translation initiation; and therefore represents an attractive process for cancer drug discovery. Previously, replacement of the 7-Me group of the Me(7)-guanosine monophosphate with a benzyl group has been found to increase binding affinity to eIF4E. Recent X-ray crystallographic studies have revealed that the cap-binding pocket undergoes a unique structural change in order to accommodate the benzyl group. To explore the structure-activity relationships governing the affinity of N(7)-benzylated guanosine monophosphate (Bn(7)-GMP) for eIF4E, we virtually screened a library of 80 Bn(7)-GMP analogs utilizing CombiGlide as implemented in Schrodinger. A subset library of substituted Bn(7)-GMP analogs was synthesized and their dissociation constants (K(d)) were determined. Due to the poor correlation between docking/scoring results and experimental binding affinities, three-dimensional quantitative structure-activity relationship (3D-QSAR) calculations were performed. Two highly predictive and self-consistent CoMFA (comparative molecular field analysis) and CoMSIA (comparative molecular similarity indices analysis) models were derived and optimized. These models may be useful for the future design of eIF4E cap-binding antagonists., (Copyright (c) 2009 Elsevier Masson SAS. All rights reserved.)