Stereoselective synthesis towards unnatural proline-based amino acids

A catalytic diastereoselective Mannich reaction promoted by chiral bifunctional urea-type organocatalysts has been developed. Treatment of N-Boc-3-ketoproline with N-Boc-aldimines under mild conditions afforded the corresponding unnatural proline based amino acid derivatives with excellent diastereoselectivities (up to 99:1) and enantioselectivities (up to 97% ee). The relative configuration of the chiral reaction products was deduced by the comparsion of the experimentally observed ECD spectra to that obtained theorectically

Inhibition of GSK-3 induces differentiation and impaired glucose metabolism in renal cancer

Glycogen synthase kinase-3 (GSK-3), a constitutively active serine/threonine kinase, is a key regulator of numerous cellular processes ranging from glycogen metabolism to cell cycle regulation and proliferation. Consistent with its involvement in many pathways, it has also been implicated in the pathogenesis of various human diseases including Type II diabetes, Alzheimer's disease, bipolar disorder, inflammation and cancer. Consequently it is recognized as an attractive target for the development of new drugs. In the present study, we investigated the effect of both pharmacological and genetic inhibition of GSK-3 in two different renal cancer cell lines. We have shown potent anti-proliferative activity of 9-ING-41, a maleimide-based GSK-3 inhibitor. The anti-proliferative activity is most likely caused by G0-G1 and G2-M phase arrest as evident from cell cycle analysis. We have established that inhibition of GSK-3 imparted a differentiated phenotype in renal cancer cells. We have also shown that GSK-3 inhibition induced autophagy, likely as a result of imbalanced energy homeostasis caused by impaired glucose metabolism. Additionally, we have demonstrated the antitumor activity of 9-ING-41 in two different subcutaneous xenograft RCC tumor models. To our knowledge, this is the first report describing autophagy induction due to GSK-3 inhibition in renal cancer cells

P2X purinergic receptor ligands: recently patented compounds

Importance of the field: P2X channels are ionotropic purinergic receptors that are currently under scrutiny as attractive targets for novel therapeutics in areas including chronic inflammation, pain and depression. Their wide expression in the CNS, recent advances in the biochemical and pharmacological properties as well as increasing numbers of patents published in this research domain demand a review in this field. Areas covered in this review: The patent literature covering novel drug-like antagonists for each P2X receptor subtype (P2X1R to P2X7R) up to December 2009 is described in this review article together with their recent highlights in pharmacology. What the reader will gain: Readers will gain an up-to-date overview of patents covering drug-like antagonists for seven P2X receptor subtypes within the last 4 years. Take home message: P2X7R antagonists and other P2X inhibitors will probably be on the market for combating rheumatoid arthritis and other diseases. Some P2X7R antagonists are already in Phase I and II clinical trials

Molecular Probes for P2X7 Receptor Studies

The ionotropic P2X7 receptor (P2X7R) has become the focus of intense research interest for a number of reasons: i) it is a cation selective ion channel that is modulated by extracellular ATP. Upon stimulation by high concentrations of ATP it generates a non-selective membrane pore which is permeable to hydrophilic molecules with molecular weight up to 900 Da. ii) Though its physiological function is yet to be fully understood, there is high P2X7R expression in microglia. Importantly, this implies a pivotal role for the P2X 7R in neuro-inflammatory and -degenerative processes. In addition, P2X7R-stimulated release of traditional neurotransmitters in the brain, such as glutamate and GABA, further supports the involvement of P2X7R in neuro-inflammatory and -degenerative processes. P2X7-knockout animals are also found to be resistant to inflammation and neuropathic pain, which suggests that P2X7 antagonists could potentially serve as all-purpose analgesics. Recent advances in the development of P2X7R ligands have resulted in identification of several different classes of P2X7R antagonists, including ATP analogues (oxidized ATP), dyes (Brilliant Blue G), tyrosine derivatives (KN-62 and KN-04), cyclic imides, adamantane and benzamide derivatives. A KN-62 related radioligand has also recently been reported for use in receptor binding assays. A more extensive range of potent, selective P2X7R ligands is required for a better understanding of the cascade of cellular processes associated with the P2X 7R. This article will review P2X7R ligands discovered to date, together with their biological activity and therapeutic potential

Purinergic P2X7 Receptor Antagonists: Chemistry and Fundamentals of Biological Screening

The purinergic P2X7 receptor is a unique member of the ATP-gated P2X family. This receptor has been implicated in numerous diseases and many structurally diverse ligands have been discovered via high throughput screening. This perspective will attempt to highlight some of the most recent key findings in both the biology and chemistry

Facile synthesis and antimycobacterial activity of isoniazid, pyrazinamide and ciprofloxacin derivatives

Several rationally designed isoniazid (INH), pyrazinamide (PZA) and ciprofloxacin (CPF) derivatives were conveniently synthesized and evaluated in vitro against H37Rv Mycobacterium tuberculosis (M. tb) strain. CPF derivative 16 displayed a modest activity (MIC = 16 µg/ml) and was docked into the M. tb DNA gyrase. Isoniazid-pyrazinoic acid (INH-POA) hybrid 21a showed the highest potency in our study (MIC = 2 µg/ml). It also retained its high activity against the other tested M. tb drug-sensitive strain (DS) V4207 (MIC = 4 µg/ml) and demonstrated negligible cytotoxicity against Vero cells (IC50 ≥ 64 µg/ml). Four tested drug-resistant (DR) M. tb strains were refractory to 21a, similar to INH, whilst being sensitive to CPF. Compound 21a was also inactive against two non-tuberculous mycobacterial (NTM) strains, suggesting its selective activity against M. tb. The noteworthy activity of 21a against DS strains and its low cytotoxicity highlight its potential to treat DS M. tb

Development of antidepressant drugs through targeting a4ß2-nicotinic acetylcholine receptors

© Springer Science+Business Media New York 2016. Nicotinic acetylcholine receptors (nAChRs) represent a family of ligand-gated ion channels that are ubiquitously distributed in the central and peripheral nervous systems. There is a considerable line of evidence both from clinical and preclinical studies supporting the notion that antagonism or partial agonism of these receptors, particularly the a4ß2-containing subunits, could lead to antidepressant-like effects in vivo. In this chapter, an overview of the fundamental neuropharmacology of a4ß2-nAChRs underpinning its association with depression is covered, including the original cholinergic hypothesis of depression proposed by Janowsky in the 1970s. The primary section highlights important structural classes of compounds that have been reported to mediate antidepressant-like effects through targeting of a4ß2-nAChRs with an emphasis on their potency, selectivity, pharmacokinetics, and drug-likeness. The pyridyl ether ligands represent the most promising scaffold for selective targeting of a4ß2-nAChRs and their antidepressant- like effects have been confirmed in animal behavioral studies. Recent advances in the field, including the use of imaging technologies for depression, are also discussed, highlighting the evolution of structural classes that have been developed as useful positron emission tomography (PET) ligands in imaging nicotinic receptors

Cubyl amides: Novel P2X7 receptor antagonists

Polycyclic amides 2 and 5–9 were successfully synthesised and their lipophilicity profiles were evaluated using reverse-phase HPLC. All synthesised compounds possessed P2X7R antagonistic properties when tested on rat spinal cord microglia cells. Extensive screening for binding to other neuroreceptor subtypes demonstrated their P2X7 selectivity

Design, synthesis and antimycobacterial evaluation of novel adamantane and adamantanol analogues effective against drug-resistant tuberculosis

The treacherous nature of tuberculosis (TB) combined with the ubiquitous presence of the drug-resistant (DR) forms pose this disease as a growing public health menace. Therefore, it is imperative to develop new chemotherapeutic agents with a novel mechanism of action to circumvent the cross-resistance problems. The unique architecture of the Mycobacterium tuberculosis (M. tb) outer envelope plays a predominant role in its pathogenesis, contributing to its intrinsic resistance against available therapeutic agents. The mycobacterial membrane protein large 3 (MmpL3), which is a key player in forging the M. tb rigid cell wall, represents an emerging target for TB drug development. Several indole-2-carboxamides were previously identified in our group as potent anti-TB agents that act as inhibitor of MmpL3 transporter protein. Despite their highly potent in vitro activities, the lingering Achilles heel of these indoleamides can be ascribed to their high lipophilicity as well as low water solubility. In this study, we report our attempt to improve the aqueous solubility of these indole-2-carboxamides while maintaining an adequate lipophilicity to allow effective M. tb cell wall penetration. A more polar adamantanol moiety was incorporated into the framework of several indole-2-carboxamides, whereupon the corresponding analogues were tested for their anti-TB activity against drug-sensitive (DS) M. tb H37Rv strain. Three adamantanol derivatives 8i, 8j and 8l showed nearly 2- and 4-fold higher activity (MIC = 1.32 – 2.89 µM) than ethambutol (MIC = 4.89 µM). Remarkably, the most potent adamantanol analogue 8j demonstrated high selectivity towards DS and DR M. tb strains over mammalian cells [IC50 (Vero cells) ≥ 169 µM], evincing its lack of cytotoxicity. The top eight active compounds 8b, 8d, 8f, 8i, 8j, 8k, 8l and 10a retained their in vitro potency against DR M. tb strains and were docked into the MmpL3 active site. The most potent adamantanol/adamantane-based indoleamides 8j/8k displayed a two-fold surge in potency against extensively DR (XDR) M. tb strains with MIC values of 0.66 and 0.012 µM, respectively. The adamantanol-containing indole-2-carboxamides exhibited improved water solubility both in silico and experimentally, relative to the adamantane counterparts. Overall, the observed antimycobacterial and physicochemical profiles support the notion that adamantanol moiety is a suitable replacement to the adamantane scaffold within the series of indole-2-carboxamide-based MmpL3 inhibitors