Medicinal Chemistry - Volume 12, Issue 1, 2016

Metabolic syndrome is a disorder described by reduced insulin sensitivity, overweight, hyperlipidaemia, high blood pressure and myocardial disorders, mainly due to high fat diet and lack of physical activity. The peroxisome proliferator activated receptors (PPARs) are type II nuclear hormone receptors that regulate a number of processes in living systems, such as metabolism of carbohydrates and fatty acids, growth and differentiation of cell, and inflammatory reactions. Alpha, gamma and delta are the three distinct isoforms of PPAR. The stimulation of PPARδ alters body’s energy fuel preference from glucose to fat. The PPARδ isoform is expressed ubiquitously in all tissues, especially in those tissues which involved in metabolism of lipids like adipose tissue, liver, kidney, and muscle. Currently, PPARδ is an emerging therapeutic target for the pharmacological therapy of disorders associated with metabolic syndrome. Several PPARδ selective agonists had been reported in last ten years, many of them had been advanced into the late phase of clinical trials such as Endurobol (GW501516). However, no PPARδ agonists are yet approved for human use. The present work had been planned to cover wide variety of PPARδ agonists reported till now along with their potential role to tackle various metabolic disorders. The present review has been planned to focus mainly the most popular PPARδ agonists.

Sucrose octa(N-ethyl)carbamate was synthesized directly from sucrose and ethyl isocyanate, and its structure was confirmed by various analytical methods, such as 1H and 13C NMR, FTIR, m.p., MS, and optical rotation. Its antibacterial, antifungal and cytotoxic activities were investigated. It exhibited strong inhibition against all bacteria tested, namely S. aureus (MIC 0.18±0.006), B. cereus (MIC 0.094±0.000), M. flavus (MIC 0.28±0.01), L. monocytogenes (MIC 0.18±0.006), P. aeruginosa (MIC 0.094±0.002), S. typhimurium (MIC 0.094±0.002), E. coli (MIC 0.18±0.006) and E. cloacae (MIC 0.18±0.006) and strong antifungal activity towards T. viride (MIC 0.09 ± 0.006), A. versicolor (MIC 0.18 ± 0.01), A. ochraceus (MIC 0.375 ± 0.01) and P. ochrochloron (MIC 0.375 ± 0.04). Furthermore, it showed moderate antitumor potential against human breast (GI50 357.20±14.12), colon (GI50 332.43±11.19) and cervical (GI50 282.67±3.97) cell lines and, more important, without hepatotoxicity.

Histone deacetylases (HDACs) inhibitors have multiple effects targeting the cancer cells and have become one of the promising cancer therapeutics with possibly broad applicability. Combination of HDAC inhibitors with the cytotoxic fluorouracil (5-FU) showed additive and synergistic effects both in vitro and in vivo. To explore the possibility in cancer therapy of a bivalent agent that combines two bioactive groups within a single molecular architecture, we designed and synthesized new dual-acting compounds by combining the bioactive fragment of MS-275, a clinical HDACs inhibitor, with cytotoxic agent 5-FU. The target compounds 9a and 9b showed comparable HDACs inhibition with MS-275 and moderate antiproliferative acitivities against six cancer cells lines.

A series of 3-benzyloxyhydantoin derivatives were designed and synthesized by introducing hydroxyurea pharmacophore into hydantoin rigid scaffold. The cytotoxic activities of the target compounds were evaluated in vitro against three cancer cell lines. Compounds 5b, 5c, 5e, 5g, 6c and 6g displayed high activity on all of the three cancer cell lines and the most promising compounds were 5g, 6g with IC50 values of 0.04 and 0.01μM. Binding of derivatives for the ribonucleotide reductase (RR) was investigated by use of molecular docking studies. Our findings show that modification at the C5 position of hydantoin with isopropyl or isobutyl was favorable to increasing binding affinity to the active site of the RR receptor and antiproliferative activity.

Penetration of the blood brain barrier (BBB) by appropriate fluorescent probes remains a challenge in optical imaging and diagnostics. We designed, synthesized and observed the in vivo BBB penetration of a LASER syn-bimane probe. Results demonstrate that the Aib transporter unit in our probe may lead a fluorescent bimanyl moiety across the BBB.

2-Arylquinazolin-4(3H)-ones (1-25) were synthesized, and evaluated for their xanthine oxidase inhibitory activity. Significant to moderate activities were exhibited by the compounds 1-3, 7, 9, 13-15, 19-21, and 23 with IC50 between 2.80 - 28.13 μM as compared to the standard allopurinol (IC50 (IC50 = 2.01 ± 0.01 μM). Compounds 4-6, 8, 11-12, 16-18, 22, and 24 demonstrated a weak activity with IC50 values 44.60 - 112.60 μM. Nonetheless, compounds 10 and 25 did not show any activity. Amongst all derivatives, compound 2, containing a C-4´ dimethylamino group, was the most potent inhibitor of the enzyme with an IC50 value comparable to the standard. Kinetics studies on the most active compounds (2, 7, 9, 14, 15, 19, and 20) were conducted in order to determine their modes of inhibition and dissociation constants Ki. Some of the compounds of 2-arylquinazolin-4(3H)-one series were thus identified as potential leads for further studies towards the treatment of hyperuricemia and gout.

Oseltamivir and Zanamivir are two of the recently licensed neuraminidase inhibitors used for the treatment of influenza. However, alternative antiviral agents are needed due to the development of resistant mutations in Oseltamivir subtype H1N1 and H5N1 avian influenza A viruses, the latter being a highly pathogenic avian virus that can be transferred to humans upon immediate contact with H5N1 infected poultry or surface. Novel drug inhibiting group 1 neuraminidases may potentially be developed through addition of extra substituent moieties to existing inhibitor skeletons. Another approach involves virtual screening of existing inhibitor skeletons which we have reported using novel ligands of H5N1 via virtual screening approach. In this study, we have used 3D structure of avian influenza virus H5N1 neuraminidase as target against a ligand dataset of four known neuraminidase inhibitors for in silico analysis. Using the dataset of known four inhibitors, a pharmacophore model was developed using ligand-based pharmacophore modeling strategy. This pharmacophore model was then used for virtual screening of natural compounds library taken from Princeton database. New hits that shared features of our pharmacophore model and binding interactions with receptor residues have been reported in this study. As more antiviral agents are required, the reported hits in our study may play an important role as novel antiviral agents against influenza virus.

In an attempt to discover novel anti-cancer agents and potent cholinesterase inhibitors, 11 azomethine-dihydroquinazolinone conjugates were evaluated against lung carcinoma cells and cholinesterases. Most of the compounds exhibited significant cytotoxicity at low micromolar concentrations and were less toxic to normal cells. After 24 h incubation period, 2i showed maximum cytotoxicity. The 4-bromine substituted compounds showed higher acetylcholinesterase (AChE) inhibitory activity than other screened compounds. The most active compound 2c, among the series, had an IC50 value 209.8 μM against AChE. The tested compounds showed less inhibition against butyrylcholinesterase. Molecular docking studies were performed in order to investigate the plausible binding modes of synthesized compounds. The compounds can be further optimized to treat cancer and Alzheimer’s disease. These derivatives may open new pathways for introducing new therapies for curing cancer and senile dementia.

A new library of N,N,N’,N’ -tetradentate pyrazoly compounds containing a pyrazole moiety was synthesized by the condensation of (3,5-dimethyl-1H-pyrazol-1-yl)methanol 2a or (1H-pyrazol-1-yl)methanol 2b with a series of primary diamines in refluxed acetonitrile for 6h. The antifungal activity against the budding yeast Saccharomyces cerevisiae, as well as the antibacterial activity against Escherichia coli of these new tetradentate ligands were studied. We found that these tetradentate ligands act specifically as antifungal agents and lack antibacterial activity. Their biological activities depend on the nature of the structure of the compounds.

A series of novel substituted 2-amino-5-(1-(4-isobutylphenyl)ethyl)-1,3,4-thiadiazoles were designed, synthesized and evaluated as anti-inflammatory and analgesic agents. Compounds were characterized by elemental and spectroscopic analysis. Compounds possessing significant activities were screened for ulcerogenic activity. Compound-5 (2-(4-isobutylphenyl)-N-(5-(1-(4- isobutylphenyl)ethyl)-1,3,4-thiadiazol-2-yl)-propanamide) produces significant in vitro antiinflammatory activity (72.5%) as compared to ibuprofen (47.7%), while compound-3f (2-(Ncyclohexyl- N-methylamino)-N-(5-(1-(4-isobutylphenyl)-ethyl)-1,3,4-thiadiazol-2-yl)-acetamide) showed 64.1 % activity. Results indicate that compound-4 (N-(5-(1-(4-isobutyl-phenyl)-ethyl)-1,3,4-thiadiazol-2-yl)-acetamide) exhibited highest analgesic activity (69.8%), where as compound-5 possessed 65.5% activity. Structure based drug design was also investigated to reveal the mechanism of action and specificity of our compounds against COX-2 enzyme. Anti-inflammatory activity and ulcerogenic potential were in agreement with the molecular modeling studies carried out on cycloxygenase enzyme.