Medicinal Chemistry - Volume 10, Issue 4, 2014

Fatty acid binding protein 4 (FABP4) is expressed in adipocytes and macrophages, and modulates inflammatory and metabolic response. Studies in FABP4-deficient mice have shown that this lipid carrier has a significant role within the field of metabolic syndrome, inflammation and atherosclerosis; thus, its inhibition may open up new opportunities to develop novel therapeutic agents. A number of potent small molecule inhibitors of FABP4 have been identified and found to have the potential to prevent and treat metabolic diseases such as type-2 diabetes and atherosclerosis. Due to the ubiquity of endogenous fatty acids and the high intracellular concentration of FABP4, the inhibitors need to have significantly greater intrinsic potency than endogenous fatty acids. Furthermore, heart-type FABP (FABP3), which is expressed in both heart and skeletal muscle, is involved in active fatty acid metabolism where it transports fatty acids from the cell membrane to mitochondria for oxidation. However, FABP3 shares high overall sequence identity and similar 3D structure with FABP4, but has a potential problem with selectivity. In this review, we would like to analyze the main inhibitors that have appeared in the literature in the last decade, focusing on chemical structures, biological properties, selectivity and structure-activity relationships.

The antitumor activity of antibacterial and antifungal compounds has been of interest in the past. In several investigations glycopeptide antibiotics like bleomycin and antifungal agents like itraconazole have shown direct positive results whereas antifungal polyenes such as amphotericin B have been shown to potentiate the effects of antitumor agents. After having investigated the fluorescence-marked antibacterial glycopeptides vancomycin and ramoplanin on various malignant and healthy human cells in previous studies, the present work is focused on the antifungal polyene nystatin. We coupled nystatin to the fluorescent dye fluorescein isothiocyanate (FITC). After confirming the correct mass by mass spectrometry the effect of the conjugate on nine different human cell lines (two benign and seven tumor cell lines) was examined. The character of the uptake was determined by confocal laser scanning microscopy (CLSM) and the uptake was quantified by fluorescence activated cell sorting (FACS). The addition of propidium iodide (PI) allowed for detection and quantification of cell membrane disruption caused by the fluorescein-nystatin conjugate. Uptake of the conjugate was found to vary among the nine cell lines investigated. Conjugate uptake was strongest after 6 hours in most cell lines. Only the two prostate carcinoma cell lines PC3 and LNCaP showed further increase in uptake after long-time (24h) incubation. PI staining in general correlated well with the conjugate FITC staining values. The Colo205 colon carcinoma cell line and the U373 and LN18 glioblastoma cell lines exhibited very low conjugate uptake and PI staining. The results indicate that this conjugate shows potential for future imaging studies on certain human cancer cells.

Thiazolidinones, synthesized from multicomponent reactions of 2-heteroarylmethylamine, arenealdehydes and mercaptoacetic acid, have been tested against six yeasts, namely Candida albicans, C. parapsilosis, C. guilliermondii, Cryptococcus laurentii, Trichosporon asahii and Rhodotorula spp. The activities were expressed as minimum inhibitory concentrations (MIC) and the minimum fungicidal concentrations (MFC). The most affected yeasts were Rhodotorula spp and T. asahii. The cytotoxicities of the thiazolidinones against the fibroblast 3T3/NIH cell line are also described. The antifungal results and the low cytotoxicity of the compounds in this work provide good guides for the further development of active compounds.

Previous structure-activity relationship studies involving a series of lactone-based muscarinic ligands identified a lead compound containing a diphenylmethylpiperazine moiety (4; IC50 = 340 nM). The purpose of the present work is to investigate 1,3-benzodioxoles, 4,4-diethyl substituted tetrahydrofurans, 5-substituted oxazolidinones and chromones as bioisosteric replacements for the lactone ring in a novel series of muscarinic ligands. The approach provided compounds with improved % inhibition values and identified a non-selective muscarinic ligand with an IC50 value of 280 nM. The structure-activity relationship for this new series will be discussed. Selected compounds were evaluated in preliminary assays for subtype selectivity and were found to be non-selective.

Diels-Alder reaction between furan and maleic anhydride resulted in 5,6-dehydro norcantharidin, then norcantharidin was obtained by reduction. The substituted-carboxylic acid was condensed with N-aminothiourea in presence of phosphorus oxychloride, yielding 2-amino-1,3,4-thiadiazole derivatives. Novel norcantharidin derivatives were synthesized with acylation, then intramolecular condensation using norcantharidin (or 5,6-dehydro norcantharidin) and 2-amino- 1,3,4-thiadiazole derivatives. All the target compounds were confirmed by IR, 1HNMR, ESI-MS and were reported for the first time. Norcantharidin derivatives antiproliferative assay was tested by MTT method against A549 and PC-3 cell lines. The results showed that all the norcantharidin derivatives displayed moderate inhibitory activities.

The present paper reports an easy preparation of imines of N-methyl-1H-indole-3-carboxaldehyde by its condensation with alkyl and aromatic amines in ethanol without using any catalyst or dehydrating agent. The compounds have been screened for their antibacterial, antifungal, crown gall tumor inhibitory, and cytotoxic activities. As a major finding some of the compounds exhibited potential biological activity. The imine containing a 4-chlorophenyl group exhibits potential antitumor activity and brine shrimp lethality against crown gall tumor and brine shrimps, respectively. Furthermore, this imine containing a 4-chlorophenyl group also exhibits significant antifungal activity against Candida albicans fungal strains. The compound containing N-diphenylmethyl group has been observed most active against the Gram-positive bacteria.

Herpes simplex virus type 1 (HSV-1), a member of the Herpesviridae family, is a ubiquitous, contagious, hostadapted pathogen that causes a wide variety of disease states, such as herpes labialis (“cold sores”) and encephalitis. Recently, due to the appearance of acyclovir-resistant HSV-1 mutants, a rapidly growing area of research has been the identification of novel small molecules (whether found in traditional medicine or not) with antiviral activity. One group of these novel pre-drugs is gallic acylate polyphenols. Here, detailed insight into the influence of the chemical structure on anti- HSV-1 activity of gallic acylate polyphenols has been provided based on an exploration of structure-function relationships through self-organizing maps and counterpropagation neural networks. A number of descriptors were investigated to construct optimized models. The resulting model exhibits a correct prediction rate of 90.67%, with active molecule classification accuracy higher than 95.00%, demonstrating that the electrostatic effect and distance between atoms are related to HSV-1 inhibition for these gallic acylate polyphenols. The results provide insights into the influence of the chemical structure on anti-HSV-1 activity of gallic acylate polyphenols.

Pharmacophore models of human dihydroorotate dehydrogenase (HsDHODH) have been developed using Discovery Studio V2.1 with a training set of 27 HsDHODH inhibitors. With one hydrogen bond receptor, two hydrophobic, one ring aromatic and one neg ionizable features, Hypo 1 has a correlation coefficient of 0.948, cost difference of 78.894, and RMSD 0.926. This model was validated by test set and Fischer randomization test. Hypo 1 was employed as a 3D query to identify potent molecules from our lab chemical database. Compound 38-C11 had Hypo 1 estimated IC50 of 489 nM. Then 38-C11 was synthesized and evaluated in HsDHODH inhibition assay. The IC50 of 38-C11 was 136.9 nM suggesting that 38-C11 could be proceeded for further evaluation in future study.

A series of new analogs fluorine containing heterocyclic system viz. 4-benzofuran-2-yl-6-phenyl-pyrimidin-2- ylamine has been synthesized and evaluated for in vitro antibacterial and antifungal activities. Microwave assisted Claisen-Schmidt condensation of 2-acetylbenzofuran (3) with fluorinated benzaldehydes (4) afforded corresponding fluorinated chalcones (5a-g). The cyclocondensation of chalcones with guanidine hydrochloride in alkaline media under microwave resulted in the formation of corresponding fluorine containing 4-benzofuran-2-yl-6-phenyl-pyrimidin-2- ylamines (6a-g). All the synthesized compounds have been characterized on the basis of analytical and spectral data and were screened for their antibacterial and antifungal activities. Some of the synthesized compounds showed good antimicrobial activities against bacteria and fungi.

Two series of compounds (AB and APB) bearing substituted phenoxy groups at 2-position of benzimidazole nucleus through amino or phenyleneamino were synthesized and evaluated through PASS software for predicting the activity spectrum of each compound. All compounds of both the series were predicted to have potent anthelmintic activity. The activity of each compound was evaluated experimentally at the concentrations of 0.1, 0.2 and 0.5% in terms of mortality time and paralysis time of the helminthes and was found to comply with the PASS predicted activity. In general, all compounds of APB series were more potent than those of AB series probably due to the additional hydrophobic interactions of the spacer phenyl ring in the APB series. The activity of all compounds was found to increase with increasing concentration. The compound with p-chlorophenoxy moiety was the most active from the APB series (mortality time 5.7±0.4 min and paralysis time 3.1±0.3 min) and equipotent to albendazole (mortality time 5.4±0.1 min and paralysis time 2.8±0.2 min) at concentration of 0.2%. The o-chlorophenoxy analogs in both the series were found to be the least active of all. Based on these results, a substituent capable of binding with the receptor through van der Waals and/or electronic interactions at 4-position of the phenoxy ring in the compound is suggested to increase binding interaction leading to potent anthelmintic activity.

Protein lysine methyltransferase G9a, which catalyzes methylation of lysine 9 of histone H3 (H3K9) and lysine 373 (K373) of p53, is overexpressed in human cancers. This suggests that small molecular inhibitors of G9a might be attractive antitumor agents. Herein we report our efforts on the design of novel G9a inhibitor based on the 3D quantitative structure-activity relationship (3D-QSAR) analysis of a series of 2,4-diamino-7-aminoalkoxyquinazolineas G9a inhibitors. The 3D-QSAR model was generated from 47 compounds using docking based molecular alignment. The best predictions were obtained with CoMFA standard model (q2 =0.700, r2 = 0.952) and CoMSIA model combined with steric, electrostatic, hydrophobic, hydrogen bond donor and acceptor fields (q2 = 0.724, r2 =0.960). The structural requirements for substituted 2,4-diamino-7-aminoalkoxyquinazoline for G9a inhibitory activity can be obtained by analysing the COMSIA plots. Based on the information, six novel follow-up analogs were designed.