Benzo[d]thiazole-2-carbanilides as new anti-TB chemotypes: Design, synthesis, biological evaluation, and structure-activity relationship.

Tuberculosis is the second leading cause of deaths worldwide. The inadequacy of existing drugs to treat TB due to developed resistance and TB-HIV synergism urges for new anti-TB drugs. Seventy-two benzo[d]thiazole-2-carbanilides have been synthesized through CDI-mediated direct coupling of benzo[d]thiazole-2-carboxylic acids with aromatic amines using a three step methodology which includes a green protocol for synthesis of ethyl benzo[d]thiazole-2-carboxylates, precursor of the desired carboxylic acids. The compounds were evaluated in vitro for anti-tubercular activity against M. tuberculosis H37Rv (ATCC27294 strain). Thirty-two compounds exhibiting MIC values in the range of 0.78-6.25 µg/mL (1.9-23 µM) were subjected to cell viability test against RAW 264.7 cell lines and thirty compounds were found to be non-toxic (<50% inhibition). The most active compounds with MIC of 0.78 µg/mL (e.g., 4i, 4n, 4s, 4w, 6f, 6h, 6u, 7e, 7h, 7p, 7r and 7w) exhibit therapeutic index of 64. The structure activity relationship of the N-arylbenzo[d]thiazole-2-carboxamides has been established for anti-mycobacterial activity. Molecular docking suggests that the compounds 7w, 4i and 4n bind to the catalytic site of the enzyme ATP Phosphoribosyltransferase (HisG) and might be attributed to their anti-TB potential. These can serve as a new starting point for the development of anti-TB agents with therapeutic potential.

Dual-target-directed 1,3-diphenylurea derivatives: BACE 1 inhibitor and metal chelator against Alzheimer's disease.

Dual-target-directed 1,3-diphenylurea derivatives were designed by hybridizing BACE 1 inhibitor 1 with metal chelator LR-90. A database consisted of 1,3-diphenylurea derivatives was built and screened by the pharmacophore model (Hypo 1) of BACE 1 inhibitor. Based on the predicted results, 11 compounds (6a-d, 9a-g) with favorable Fitvalues were selected, synthesized and evaluated for their BACE 1 inhibitory activities, which showed that the predicted results were in good agreement with the experimental values. Besides, the synthesized compounds also displayed the ability to chelate metal ions. The most effective BACE 1 inhibitor 9f (27.85+/-2.46 micromol/L) was selected for further receptor-binding studies, the result of which indicated that an essential hydrogen bonds was formed between the urea group of 9f and the catalytic aspartate Asp228.

Recent advances in the development of multi-kinase inhibitors.

During the last two decades, protein kinases have emerged as a major target for cancer therapy and a large number of selective kinase inhibitors have been developed as potential anticancer drugs. To avoid unpredictable toxic effects, researchers usually aim at designing highly selective inhibitors. But since the formation and progression of a tumor has to be considered as a multifactorial process, which is dependent on different signalling pathways, it seems reasonable to establish anticancer therapies that target several kinases associated with tumor growth. In general, this can be achieved by two different strategies, either by concomitantly using a combination of a set of selective kinase inhibitors or by administering a single agent, which simultaneously inhibits several kinases, a so called multi-kinase inhibitor. In this review, benefits and obstacles of both strategies are discussed. An overview over recently approved and newly upcoming multi-kinase inhibitors is given.

1-[4-(1H-Benzoimidazol-2-yl)-phenyl]-3-[4-(1H-benzoimidazol-2-yl)-phenyl]-urea derivatives as small molecule heparanase inhibitors.

A novel class of 1-[4-(1H-benzoimidazol-2-yl)-phenyl]-3-[4-(1H-benzoimidazol-2-yl)-phenyl]-ureas are described as potent inhibitors of heparanase. Among them are 1,3-bis-[4-(1H-benzoimidazol-2-yl)-phenyl]-urea (7a) and 1,3-bis-[4-(5,6-dimethyl-1H-benzoimidazol-2-yl)-phenyl]-urea (7d), which displayed good heparanase inhibitory activity (IC(50) 0.075-0.27 microM). Compound 7a showed good efficacy in a B16 metastasis model.

Discovery of cell-permeable non-peptide inhibitors of beta-secretase by high-throughput docking and continuum electrostatics calculations.

A fragment-based docking procedure followed by substructure search were used to identify active-site beta-secretase inhibitors from a composite set of about 300 000 and a library of nearly 180 000 small molecules, respectively. EC(50) values less than 10 microM were measured in at least one of two different mammalian cell-based assays for 12 of the 72 purchased compounds. In particular, the phenylureathiadiazole 2 and the diphenylurea derivative 3 are promising lead compounds for beta-secretase inhibition.

CCR5 antagonists as anti-HIV-1 agents. Part 2: Synthesis and biological evaluation of N-[3-(4-benzylpiperidin-1-yl)propyl]-N,N'-diphenylureas.

We have previously reported the novel lead compound 1a as a CCR5 antagonist for treatment of HIV-1 infection. SAR studies on incorporating various acyl groups as a replacement for the 5-oxopyrrolidine-3-carbonyl group of the lead structure resulted in the discovery of N-[3-(4-benzylpiperidin-1-yl)propyl]-N,N'-diphenylurea (4a) with significantly improved CCR5 binding affinity. Substitutions (4-Cl, 4e,f; 4-Me, 4i) on the N'-phenyl ring further increased the binding affinity. Introduction of polar substituents on the phenyl ring of the 4-benzylpiperidine moiety enhanced the inhibitory activity of the HIV-1 envelope-mediated membrane fusion (4v,w), suggesting that polar substituents at this position can interfere effectively with HIV-1 cell entry.

A simplified and improved synthesis of [11C]phosgene with iron and iron (III) oxide.

[11C]Phosgene ([11C]COCl2), a useful precursor for labeling several radiopharmaceuticals, is generally produced by catalytic oxidation of [11C]carbon tetrachloride over Fe granules, although in low yields or with poor reproducibility. In order to develop am improved synthesis of [11C]phosgene, two oxidizing agents, Fe2O3 and CuO, were examined. The yield of [11C]phosgene was significantly increased using Fe2O3 powder mixed with Fe granules, while the use of CuO alone, or CuO powder mixed with Fe granules resulted in an insignificant yield. The yield and specific activity of S- (-) [11C]CGP-12177 synthesized using Fe2O3 powder mixed with Fe granules were markedly higher than those synthesized by the previous methods using Fe granules alone or Fe granules mixed with Fe powder. Thus, in the present study, we developed a simple and practical method for the synthesis of [11C]phosgene, which provided an improved yield of S- (-) [11C]CGP-12177.

Antimycobacterial activity of 3,4-dichlorophenyl-ureas, N,N-diphenyl-ureas and related derivatives.

Substituted urea derivatives were prepared by reacting 3,4-dichlorophenyl isocyanate with amino acids, dipeptides, histamine or dicyandiamide among others, or from N,N-diphenyl-carbamoyl chloride and amino acids, dipeptides, or histamine. Other derivatives were obtained by reaction of PABA or PAS with arylsulfonyl halides. Some of the new compounds showed appreciable activity as antimycobacterial agents against Mycobacterium tuberculosis H37Rv, producing an inhibition of growth in the range of 80-89%, at a concentration of 6.25 microM. Some derivatives of this series might constitute interesting lead molecules for designing novel types of drugs effective against M. tuberculosis, a re-emerging pathogen both in the developed and under-developed countries.

Inhibitors of acyl-Coa:cholesterol acyltransferase. 4. A novel series of urea ACAT inhibitors as potential hypocholesterolemic agents.

We have synthesized a series of N-phenyl-N'-aralkyl and N-phenyl-N'-(1-phenylcycloalkyl)ureas as inhibitors of acyl-CoA:cholesterol acyltransferase (ACAT). This intracellular enzyme is thought to be responsible for the esterification of dietary cholesterol; hence inhibition of this enzyme could reduce diet-induced hypercholesterolemia. For this series of compounds, the in vitro ACAT inhibitory activity was improved by increasing the bulk of the 2,6-substituents on the phenyl ring. Additionally, we found that spacing of the aromatic rings was critical for ACAT inhibitory activity. A phenyl ring five atoms away from the requisite 2,6-diisopropylphenyl moiety was optimal for in vitro activity. Substitution alpha to the N'-phenyl moiety enhanced in vitro potency. In the case of phenylcycloalkyl ureas, ACAT inhibitory activity was independent of the size of the cycloalkyl ring. From this series of analogs, compound 25, which had excellent in vitro potency for inhibiting ACAT, was found to lower plasma cholesterol by 73% in vivo when administered in the diet at 50 mg/kg in an animal model of hypercholesterolemia. In this model, compound 25 lowered plasma cholesterol dose dependently and was as efficacious as the Lederle ACAT inhibitor CL 277082.

Syntheses and inhibitory effects on gastric lesions of trans-guanidinomethylcyclohexane carboxylic acid arylamides.

A novel series of trans-guanidinomethylcyclohexanecarboxylic acid (trans-GMCHA) arylamides was synthesized. The several trans-GMCHA arylamide derivatives showed more potent inhibitory effects on the stress- and HCl-ethanol-induced gastric ulcers than cetraxate in rats. In acute toxicity studies in mice, most amides showed such severe toxicity that all mice injected with these compounds (50 mg/kg, i.p.) died. However, mice injected with the trans-GMCHA (2'-,3'- and 4'-ethoxycarboxy)phenylamide (7, 8 and 9) which bear an alkyloxycarbonyl group at benzene ring survived. From these results, trans-GMCHA (2'-ethoxycarbonyl)phenylamide (7) was selected as a promising anti-ulcer agent.

Identification of the metabolites of trichlorocarbanilide in the rat.

The metabolism and excretion of 14C-labeled 3,4,4'-trichlorodiphenylurea has been studied in the rat after oral and iv administration. More than 80% of the administered radioactivity was excreted in the feces and urine over 5 days. Five isolated metabolites were characterized by mass spectrometry and by comparative thin-layer chromatography with synthesized compounds. Metabolites found include 2'-hydroxy-, 3'-hydroxy-, 6-hydroxy-, 2',6-dihydroxy- and 3',6-dihydroxy-3,4,4'-trichlorodiphenylurea.

The metabolism and toxicity of halogenated carbanilides. Biliary metabolites of 3,4,4'-trichlorocarbanilide and 3-trifluoromethyl-4,4'-dichlorocarbanilide in the rat.

In separate experiments, after repeated oral administration of 3,4,4'-trichlorocarbanilide (TCC) and 3-trifluoromethyl-4,4'-dichlorocarbanilide (TFC) to rats, the biliary metabolites of each were isolated and identified. The major TCC biliary metabolite was found to be 2'-hydroxy-TCC. This compound was isolated mainly from the nonconjugated and the glucuronide fractions. Other metabolites present in substantial quantities were 6-hydroxy-TCC and 2',6-dihydroxy-TCC mainly as glucuronides and 3'-hydroxy TCC mainly as the sulfate conjugate. Small amounts of 3',6-dihydroxy-TCC were isolated from each of the fractions. No unchanged TCC was found in the bile. Only traces of other metabolites were found, and no N-hydroxylated products were observed. The major TFC biliary metabolite was the glucuronide conjugate of 2'-hydroxy-TFC. The only other metabolite of TFC was 3'-hydroxy-TFC, which was the predominant metabolite in the sulfate-conjugated fraction.