Novel potent neuropeptide Y Y5 receptor antagonists: Synthesis and structure–activity relationships of phenylpiperazine derivatives

Synthesis and Structure-Activity Relationships of New 2-Phenoxybenzamides with Antiplasmodial Activity

The 2-phenoxybenzamide 1 from the Medicines for Malaria Venture Malaria Box Project has shown promising multi-stage activity against different strains of P. falciparum. It was successfully synthesized via a retrosynthetic approach. Subsequently, twenty-one new derivatives were prepared and tested for their in vitro activity against blood stages of the NF54 strain of P. falciparum. Several insights into structure-activity relationships were revealed. The antiplasmodial activity and cytotoxicity of compounds strongly depended on the substitution pattern of the anilino partial structure as well as on the size of substituents. The diaryl ether partial structure had further impacts on the activity. Additionally, several physicochemical and pharmacokinetic parameters were calculated (log P, log D₇.₄ and ligand efficiency) or determined experimentally (passive permeability and CYP3A4 inhibition). The tert-butyl-4-{4-[2-(4-fluorophenoxy)-3-(trifluoromethyl)benzamido]phenyl}piperazine-1-carboxylate possesses high antiplasmodial activity against P. falciparum NF54 (PfNF54 IC₅₀ = 0.2690 µM) and very low cytotoxicity (L-6 cells IC₅₀ = 124.0 µM) resulting in an excellent selectivity index of 460. Compared to the lead structure 1 the antiplasmodial activity was improved as well as the physicochemical and some pharmacokinetic parameters.

5-Amino-pyrazoles: potent reagents in organic and medicinal synthesis

5-Amino-pyrazoles have proven to be a class of fascinating and privileged organic tools for the construction of diverse heterocyclic or fused heterocyclic scaffolds. This review presents comprehensively the applications of 5-amino-pyrazoles as versatile synthetic building blocks in the synthesis of remarkable organic molecules with an emphasis on versatile functionalities. Following a brief introduction of synthesis methods, planning strategies to construct organic compounds, particularly diverse heterocyclic scaffolds, such as poly-substituted heterocyclic compounds and fused heterocyclic compounds via 5-amino-pyrazoles, have been summarized. Fused heterocycles are classified as bicyclic, tricyclic, tetracyclic, and spiro-fused pyrazole derivatives. These outstanding compounds synthesized via wide variety of approaches include conventional reactions, one-pot multi-component reactions, cyclocondensation, cascade/tandem protocols, and coupling reactions. 5-Amino-pyrazoles represent a class of promising functional reagents, similar to the biologically active compounds, highlighted with diverse applications especially in the field of pharmaceutics and medicinal chemistry. Notably, this critical review covers the articles published from 1981 to 2018.

Direct synthesis of pyrazoles from esters using tert-butoxide-assisted C-(C=O) coupling

This paper describes the direct synthesis of pyrazoles from esters that comprises two sequential reactions: tert-butoxide-assisted C-C(=O) coupling reaction to yield β-ketonitrile or α,β-alkynone intermediates, and condensation by hydrazine addition. The method reported allows for easy control of the regioselectivity and structure of substituents at N-1, C-3, C-4 and/or C-5 positions.

Piperazine derivatives of boronic acids – potential bifunctional biologically active compounds

The combination of a piperazine and boronic groups within one molecule can result in a totally novel biological activity.

Infrared and Raman spectra, conformational stability and vibrational assignment of 1-formylpiperazine

Infrared and Raman spectra of 1-formylpiperazine (1-fp) have been recorded in the region of 4000-50 cm(-1). The conformational analysis, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 1-fp (C5H10N2O) have been examined by means of Becke-3-Lee-Yang-Parr (B3LYP) density functional theory (DFT) method together with 6-31++G(d,p) basis set. Furthermore, reliable conformational investigation and vibrational assignments have been made by the potential energy surface (PES) and potential energy distribution (PED) analyses, respectively. Calculations are carried out with the possible six conformational isomers of 1-fp, both in gas phase and in solution using benzene and methanol. The experimental and theoretical results indicate that B3LYP method provides satisfactory evidence for the prediction vibrational wavenumbers, and the normal chair conformation with equatorial substituents is not preferred due to the steric interaction.

Alkylsulfanyl-1,2,4-triazoles, a new class of allosteric valosine containing protein inhibitors. Synthesis and structure-activity relationships

Valosine containing protein (VCP), also known as p97, is a member of AAA ATPase family that is involved in several biological processes and plays a central role in the ubiquitin-mediated degradation of misfolded proteins. VCP is an ubiquitously expressed, highly abundant protein and has been found overexpressed in many tumor types, sometimes associated with poor prognosis. In this respect, VCP has recently received a great deal of attention as a potential new target for cancer therapy. In this paper, the discovery and structure-activity relationships of alkylsulfanyl-1,2,4-triazoles, a new class of potent, allosteric VCP inhibitors, are described. Medicinal chemistry manipulation of compound 1, identified via HTS, led to the discovery of potent and selective inhibitors with submicromolar activity in cells and clear mechanism of action at consistent doses. This represents a first step toward a new class of potential anticancer agents.

Synthesis and in vitro evaluation of oxindole derivatives as potential radioligands for 5-HT(7) receptor imaging with PET

The most recently discovered serotonin (5-HT) receptor subtype, 5-HT(7), is considered to be associated with several CNS disorders. Noninvasive in vivo positron emission tomography (PET) studies of cerebral 5-HT(7) receptors could provide a significant advance in the understanding of the neurobiology and eventual dysfunctions of the 5-HT(7) receptor. To date, no appropriate 5-HT(7) receptor PET ligand has been developed. Here, we modified known 5-HT(7) selective phenylpiperazinyl-butyloxindole derivatives so that they may be labeled either with carbon-11 or fluorine-18. A set of potential 5-HT(7) ligands for PET molecular imaging was successfully synthesized. Two compounds (10 and 14) were tested against a range of targets. Both compounds display a promising in vitro profile with respect to PET imaging of the 5-HT(7) receptor in thalamic regions.

Discovery of trans-N-[1-(2-fluorophenyl)-3-pyrazolyl]-3-oxospiro[6-azaisobenzofuran-1(3H),1'-cyclohexane]-4'-carboxamide, a potent and orally active neuropeptide Y Y5 receptor antagonist

A series of trans-3-oxospiro[(aza)isobenzofuran-1(3H),1'-cyclohexane]-4'-carboxamide derivatives were synthesized to identify potent NPY Y5 receptor antagonists. Of the compounds, 21j showed high Y5 binding affinity, metabolic stability and brain and cerebrospinal fluid (CSF) penetration, and low susceptibility to P-glycoprotein transporters. Oral administration of 21j significantly inhibited the Y5 agonist-induced food intake in rats with a minimum effective dose of 1mg/kg. This compound was selected for proof-of-concept studies in human clinical trials.

Novel orally active NPY Y5 receptor antagonists: Synthesis and structure-activity relationship of spiroindoline class compounds

Spiroindoline urea derivatives, designed to act as NPY Y5 receptor antagonists, were synthesized and their structure-activity relationships were investigated. Of these derivatives, compound 3a showed good Y5 binding affinity with favorable pharmacokinetic properties. Compound 3a significantly inhibited bPP Y5 agonist-induced food intake in rats, and suppressed body weight gain in DIO mice.

Identification of novel and orally active spiroindoline NPY Y5 receptor antagonists

A series of spiroindoline-3,4'-piperidine derivatives were synthesized and evaluated for their binding affinities and antagonistic activities at Y5 receptors. Potent Y5 antagonists were tested for their oral bioavailabilities and brain penetration in rats. Some of the antagonists showed good oral bioavailability and/or good brain penetration. In particular, compound 6e was orally bioavailable and brain penetrant, and oral administration of 6e inhibited bPP-induced food intake in rats with a minimum effective dose of 10mg/kg.

1,3,4-Oxadiazoline derivatives as novel potential inhibitors targeting chitin biosynthesis: design, synthesis and biological evaluation

Two series of 1,3,4-oxadiazoline heterocycle derivatives were designed, synthesized and identified. Bioactivity assays showed that all synthesized compounds inhibited chitin synthesis in yeast, suggesting they might be a novel class of potential inhibitors against chitin biosynthesis. The structure-activity relationships (SAR) of these compounds are discussed.

Discovery of an orally bioavailable small molecule inhibitor of prosurvival B-cell lymphoma 2 proteins

Overexpression of prosurvival proteins such as Bcl-2 and Bcl-X L has been correlated with tumorigenesis and resistance to chemotherapy, and thus, the development of antagonists of these proteins may provide a novel means for the treatment of cancer. We recently described the discovery of 1 (ABT-737), which binds Bcl-2, Bcl-X L, and Bcl-w with high affinity, shows robust antitumor activity in murine tumor xenograft models, but is not orally bioavailable. Herein, we report that targeted modifications at three key positions of 1 resulted in a 20-fold improvement in the pharmacokinetic/pharmacodynamic relationship (PK/PD) between oral exposure (AUC) and in vitro efficacy in human tumor cell lines (EC 50). The resulting compound, 2 (ABT-263), is orally efficacious in an established xenograft model of human small cell lung cancer, inducing complete tumor regressions in all animals. Compound 2 is currently in multiple phase 1 clinical trials in patients with small cell lung cancer and hematological malignancies.

Syntheses and structure-activity relationships of novel, potent, and selective trans-2-[3-oxospiro[isobenzofuran-1(3H),1'-cyclohexan]-4'-yl]benzimidazole NPY Y5 receptor antagonists

Syntheses and structure-activity relationships of a novel class of 2-[3-oxospiro[isobenzofuran-1(3H),1'-cyclohexan]-4'-yl]benzimidazole NPY Y5 receptor antagonists are described. Optimization of the lead compound 2a by incorporating substituents into the 5-position or into both the 5- and 6-positions of the benzimidazole core part led to the identification of 5-(5-methyl-1,2,4-oxadiazol-2-yl)benzimidazole (2r: IC(50)=3.3 nM) and 5-(2-methyltetrazol-5-yl)benzimidazole (2u: IC(50)=5.9 nM), both of which are potent, selective, and orally bioavailable Y5 receptor antagonists.

Neuropeptide y receptor selective ligands in the treatment of obesity

Obesity is a serious public health problem throughout the world, affecting both developed societies and developing countries. The central nervous system has developed a meticulously interconnected circuitry in order to keep us fed and in an adequate nutritional state. One of these consequences is that an energy-dense environment favors the development of obesity. Neuropeptide Y (NPY) is one of the most abundant and widely distributed peptides in the central nervous system of both rodents and humans and has been implicated in a variety of physiological actions. Within the hypothalamus, NPY plays an essential role in the control of food intake and body weight. Centrally administered NPY causes robust increases in food intake and body weight and, with chronic administration, can eventually produce obesity. NPY activates a population of at least six G protein-coupled Y receptors. NPY analogs exhibit varying degrees of affinity and specificity for these Y receptors. There has been renewed speculation that ligands for Y receptors may be of benefit for the treatment of obesity. This review highlights the therapeutic potential of Y(1), Y(2), Y(4), and Y(5) receptor agonists and antagonists as additional intervention to treat human obesity.