Combinatorial Chemistry & High Throughput Screening - Volume 15, Issue 10, 2012

D2-like receptors are members of dopamine receptors, including dopamine D2 receptor (D2R), dopamine D3 receptor (D3R), and dopamine D4 receptor (D4R), which modulate behavior, cognition, and emotion. D2-like receptors are critical targets for drug development. Particularly, D3R has been identified as a therapeutic target for antipsychotic and anti-parkinsonian drugs. Recently, the crystal structure of D3R was reported. Here we summarize the available active compounds for D3R and the structure-activity relationships (SAR) studies of them. This provides lead templates for further chemical modification. We describe the structure features of the recent crystal structure of D3R and its difference from other G protein-coupled receptors (GPCRs). We provide the recognition mechanism of the inhibitors of D3R (molecular docking results and molecular dynamics results), which illustrates the interaction between the inhibitors and critical residues of D3R. Finally, we summarize the outlook of drug development for D3R. Our study provides useful information for developing high selective, high potent antagonists and agonists of D3R.

Using a support vector machine (SVM), two computational models were built to predict whether a compound is an active or weakly active strand transfer (ST) inhibitor based on a dataset of 1257 ST inhibitors of HIV-1 integrase. The model built with MACCS fingerprints gave a prediction accuracy of 91.82% and a Matthews Correlation Coeffiient (MCC) of 0.73 on test set, and the model built with 40 MOE descriptors gave a prediction accuracy of 93.64% and an MCC of 0.79 on test set. Some molecular properties such as electrostatic properties, van der Waals surface area, hydrogen bond properties and the number of fluorine atoms are important factors influencing the interactions between the inhibitor and the integrase. Some scaffolds like β-diketo acid and its derivatives, naphthyridine carboxamide or the isosteric of it and pyrimidionones may play crucial rule to the activity of the HIV-1 integrase inhibitors.

Detecting a small molecular-weight compound by electrospray ionization mass spectrometry (ESI-MS) requires the compound to obtain a charge. Factors such as gas-phase proton affinities and analyte surface activity are correlated with a positive ESI-MS response, but unfortunately it is extremely challenging to predict from a chemical structure alone if a compound is likely to yield an observable molecular-ion peak in an ESI-MS spectrum. Thus, the design of a chemical library for an ESI-MS ligand-affinity screen is particularly daunting. Only 56.9% of the compounds from our FAST-NMR functional library [1] were detectable by ESI-MS. An analysis of ∼1,600 molecular descriptors did not identify any correlation with a positive ESI-MS response that cannot be attributed to a skewed population distribution. Unfortunately, our results suggest that molecular descriptors are not a valuable approach for designing a chemical library for an MS-based ligand affinity screen.

Stable derivatives of oxaphosphaphenanthrenes were prepared by using the reactions of dialkyl acetylenedicarboxylate with 3-bromo-2-naphthol in the presence of trimethyl or triphenyl phosphite under microwave conditions at 70°C in good yields. Under similar conditions, chromene derivatives were produced by using triethyl phosphite and dialkyl acetylenedicarboxylate in the presence of OH-acids in excellent yields

A series of thiophene derivatives were synthesized via one-pot multicomponent reactions of alkyl bromids, aroyl or alkanoyl isothiocyanates, 1,3-dicarbonyl compounds and secondary amins under microwave irradiation at 80 °C. Particularly valuable features of this method include high yields of products, broad substrate scope, short reaction time and straightforward procedure.

Recyclable ZnO nano-rods catalyst as a most efficient and straightforward protocol for one-pot, threecomponent synthesis of spirooxindole derivatives at room temperature under solvent-free conditions in both reaction media and work-up procedure is described. This method is of great value because of its environmentally benign character, easy handling, high yields, convenient operation (grinding), room temperature, low cost and green.

Multicomponent reactions involving 4-hydroxycumarine, activated acetylenic compounds and N-nucleophiles under solvent-free conditions were investigated. The reactions could also be extended to quinoline or CH-acides. Substituted chromen could be obtained from this routine, which may have potential applications in drugs fields.

A series of novel diterpenoids including imines, amides and ureas with a dehydroabietyl skeleton were screened to hepatocellular carcinoma (SMMC-7721), lung cancer (A-549), glioma (C-6) and breast carcinoma (MCF-7) tumor cells by MTT method. Their antitumor activity and structure activity relationship were analyzed. Several of the title compounds such as I-2, I-10, I-6 and I-5, possess noticeable antitumor activity against SMMC-7721, A-549, C-6 and MCF-7 tumor cells, with lowest IC50 values of 6.65, 0.75, 0.81 and 10.65μM, respectively. Based on the structure-activity relationship investigation, the three kinds of diterpenoids with a dehydroabietyl skeleton show high activity to SMMC-7721 cells. Imines derivatives exhibit broad spectrum and highly efficient activities to the selected four kinds of tumor cells.

A pentafluorophenylammonium triflate (PFPAT) catalyst (10 mol%) efficiently promoted one-pot condensation of β-naphthol, aldehydes, and cyclic 1,3-dicarbonyl compounds in good to excellent yield under mild reaction conditions. These catalytic condensations have advantages from the viewpoint of green chemistry. PFPAT organocatalyst is air-stable, cost-effective, easy to handle, and easily removed from the reaction mixtures.

Three-dimensional pharmacophore hypothesis was established based on a set of known DPP-IV inhibitor using PharmaGist software program understanding the essential structural features for DPP-IV inhibitor. The various marketed or under developmental status, potential gliptins have been opted to build a pharmacophore model, e.g. Sitagliptin (MK- 0431), Saxagliptin, Melogliptin, Linagliptin (BI-1356), Dutogliptin, Carmegliptin, Alogliptin and Vildagliptin (LAF237). PharmaGist web based program is employed for pharmacophore development. Four points pharmacophore with the hydrogen bond acceptor (A), hydrophobic group (H), Spatial Features and aromatic rings (R) have been considered to develop pharmacophoric features by PharmaGist program. The best pharmacophore model bearing the Score 16.971, has been opted to screen on ZincPharmer database to derive the novel potential anti-diabetic ligands. The best pharmacophore bear various Pharmacophore features, including General Features 3, Spatial Features 1, Aromatic 1 and Acceptors 2. The PharmaGist employed algorithm to identify the best pharmacophores by computing multiple flexible alignments between the input ligands. The multiple alignments are generated by combining alignments pair-wise between one of the gliptin input ligands, which acts as pivot and the other gliptin as ligand. The resulting multiple alignments reveal spatial arrangements of consensus features shared by different subsets of input ligands. The best pharmacophore model has been derived using both pair-wise and multiple alignment methods, which have been weighted in Pharmacophore Generation process. The highest-scoring pharmacophore model has been selected as potential pharmacophore model. In conclusion, 3D structure search has been performed on the “ZincPharmer Database” to identify potential compounds that have been matched with the proposed pharmacophoric features. The 3D ZincPharmer Database has been matched with various thousands of Ligands hits. Those matches were screened through the RMSD and max hits per molecule. The physicochemical properties of various “ZincPharmer Database” screened ligands have been calculated by PaDELDescriptor software. The all “ZincPharmer Database” screened ligands have been filtered based on the Lipinski's rule-of-five criteria (i.e. Molecular Weight <500, H-bond acceptor ≤ 10, H-bond donor ≤ 5, Log P ≤ 5) and were subjected to molecular docking studies to get the potential antidiabetic ligands. We have found various substituted as potential antidiabetic ligands, which can be used for further development of antidiabetic agents. In the present research work, we have covered rational of DPP-IV inhibitor based on Ligand-Based Pharmacophore detection, which is validated via the Docking interaction studies as well as Maximal Common Substructure (MCS).