N-(4-cyanotetrahydro-2H-pyran-4-yl) and N-(1-cyanocyclohexyl) derivatives of 1,5-diarylpyrazole-3-carboxamides showing high affinity for 18 kDa translocator protein and/or cannabinoid receptors

Rationale design and synthesis of new apoptotic thiadiazole derivatives targeting VEGFR-2: computational and in vitro studies

This work presents the synthesis and in vitro, and in silico analyses of new thiadiazole derivatives that are designed to mimic the pharmacophoric characteristics of vascular endothelial growth factor receptor-2 (VEGFR-2) inhibitors. A comprehensive evaluation of the inhibitory properties of the synthesized thiadiazole derivatives against the cancer cell lines MCF-7 and HepG2 identified several auspicious candidates. Among them, compound 14 showed remarkably low IC50 values of 0.04 μM and 0.18 μM against MCF-7 and HepG2, respectively. VEGFR-2 inhibitory evaluation of compound 14 revealed a promising IC50 value in the nanomolar range (103 nM). Further examination of the cell cycle revealed that compound 14 has the ability to stop the progression of the cell cycle in MCF-7 cells via G0-G1 phase arrest. Interestingly, compound 14 also demonstrated a noteworthy pro-apoptotic effect in MCF-7 cells, with notable increases in early apoptosis (16.53%) and late apoptosis (29.57%), along with a slight increase in the population of necrotic cells (5.95%). Furthermore, compound 14 showed a significant drop in MCF-7 cells' ability to migrate and heal wounds. Additionally, compound 14 promoted apoptosis by boosting BAX (6-fold) while lowering Bcl-2 (6.2-fold). The binding affinities of the synthesized candidates to their target (VEGFR-2) were confirmed by computational investigations, including molecular docking, principal component analysis of trajectories (PCAT), and molecular dynamics (MD) simulations. Additionally, compound 14's stability and reactivity were investigated using density functional theory (DFT). These thorough results highlight compound 14's potential as a lead contender for additional research in the creation of anticancer drugs that target VEGFR-2. This work establishes a foundation for promising thiadiazole derivatives for future therapeutic developments in anticancer- and angiogenesis-related scientific fields.

Development of Yin-Yang ligand for cannabinoid receptors

Cannabinoid receptors (CBs), including CB1 and CB2, are the key components of a lipid signaling endocannabinoid system (ECS). Development of synthetic cannabinoids has been attractive to modulate ECS functions. CB1 and CB2 are structurally closely related subtypes but with distinct functions. While most efforts focus on the development of selective ligands for single subtype to circumvent the undesired off-target effect, Yin-Yang ligands with opposite pharmacological activities simultaneously on two subtypes, offer unique therapeutic potential. Herein we report the development of a new Yin-Yang ligand which functions as an antagonist for CB1 and concurrently an agonist for CB2. We found that in the pyrazole-cored scaffold, the arm of N1-phenyl group could be a switch, modification of which yielded various ligands with distinct activities. As such, the ortho-morpholine substitution exerted the desired Yin-Yang bifunctionality which, based on the docking study and molecular dynamic simulation, was proposed to be resulted from the hydrogen bonding with S173 and S285 in CB1 and CB2, respectively. Our results demonstrated the feasibility of structure guided ligand evolution for challenging Yin-Yang ligand.

From a Designer Drug to the Discovery of Selective Cannabinoid Type 2 Receptor Agonists with Favorable Pharmacokinetic Profiles for the Treatment of Systemic Sclerosis

Synthetic cannabinoids, as exemplified by SDB-001 (1), bind to both CB1 and CB2 receptors and exert cannabimimetic effects similar to (-)-trans-Δ⁹-tetrahydrocannabinol, the main psychoactive component present in the cannabis plant. As CB1 receptor ligands were found to have severe adverse psychiatric effects, increased attention was turned to exploiting the potential therapeutic value of the CB2 receptor. In our efforts to discover novel and selective CB2 receptor agonists, 1 was selected as a starting point for hit molecule identification and a class of 1H-pyrazole-3-carboxamide derivatives were thus designed, synthesized, and biologically evaluated. Systematic structure-activity relationship investigations resulted in the identification of the most promising compound 66 as a selective CB2 receptor agonist with favorable pharmacokinetic profiles. Especially, 66 treatment significantly attenuated dermal inflammation and fibrosis in a bleomycin-induced mouse model of systemic sclerosis, supporting that CB2 receptor agonists might serve as potential therapeutics for treating systemic sclerosis.

Iodine-promoted synthesis of pyrazoles from 1,3-dicarbonyl compounds and oxamic acid thiohydrazides

A novel approach to 3,4-dicarbonyl-substituted pyrazoles from 1,3-dicarbonyl compounds and oxamic acid thiohydrazides was developed via iodine-promoted cascade imination/halogenation/cyclization/ring contraction reaction.

The crystal structure of chlorido(2-(1H-pyrazol-3-yl)phenolato-κ2 N,O)(2-(1H-pyrazol-3-yl)phenol-κN)copper(II), C18H15ClCuN4O2

C18H15ClCuN4O2, triclinic, P1̄ (no. 2), a = 8.938(3) Å, b = 9.228(3) Å, c = 12.127(6) Å, α = 105.478(7)°, β = 110.358(8)°, γ = 99.727(6)°, V = 865.0(6) Å3, Z = 2, R gt(F) = 0.0504, wR ref(F 2) = 0.1447, T = 296(2) K.

Practical, mild and efficient electrophilic bromination of phenols by a new I(iii)-based reagent: the PIDA-AlBr3 system

A practical electrophilic bromination procedure for phenols and phenol-ethers was developed under efficient and very mild reaction conditions. A broad scope of arenes was investigated, including the benzimidazole and carbazole core as well as analgesics such as naproxen and paracetamol. The new I(iii)-based brominating reagent PhIOAcBr is operationally easy to prepare by mixing PIDA and AlBr3. Our DFT calculations suggest that this is likely the brominating active species, which is prepared in situ or isolated after centrifugation. Its stability at 4 °C after preparation was confirmed over a period of one month and no significant loss of its reactivity was observed. Additionally, the gram-scale bromination of 2-naphthol proceeds with excellent yields. Even for sterically hindered substrates, a moderately good reactivity is observed.

Exploring the 2- and 5-positions of the pyrazolo[4,3-d]pyrimidin-7-amino scaffold to target human A1 and A2A adenosine receptors

A new series of 7-aminopyrazolo[4,3-d]pyrimidine derivatives (1-31) were synthesized to evaluate some structural modifications at the 2- and 5-positions aimed at shifting affinity towards the human (h) A2A adenosine receptor (AR) or both hA2A and hA1 ARs. The most active compounds were those featured by a 2-furyl or 5-methylfuran-2-yl moiety at position 5, combined with a benzyl or a substituted-benzyl group at position 2. Several of these derivatives (22-31) displayed nanomolar affinity for the hA2A AR (Ki=3.62-57nM) and slightly lower for the hA1 ARs, thus showing different degrees (3-22 fold) of hA2A versus hA1 selectivity. In particular, the 2-(2-methoxybenzyl)-5-(5-methylfuran-2-yl) derivative 25 possessed the highest hA2A and hA1 AR affinities (Ki=3.62nM and 18nM, respectively) and behaved as potent antagonist at both these receptors (cAMP assays). Its 2-(2-hydroxybenzyl) analog 26 also showed a high affinity for the hA2A AR (Ki=5.26nM) and was 22-fold selective versus the hA1 subtype. Molecular docking investigations performed at the hA2A AR crystal structure and at a homology model of the hA1 AR allowed us to represent the hypothetical binding mode of our derivatives and to rationalize the observed SARs.

Considerations in the Development of Reversibly Binding PET Radioligands for Brain Imaging

The development of reversibly binding radioligands for imaging brain proteins in vivo, such as enzymes, neurotransmitter transporters, receptors and ion channels, with positron emission tomography (PET) is keenly sought for biomedical studies of neuropsychiatric disorders and for drug discovery and development, but is recognized as being highly challenging at the medicinal chemistry level. This article aims to compile and discuss the main considerations to be taken into account by chemists embarking on programs of radioligand development for PET imaging of brain protein targets.

Structural refinement of pyrazolo[4,3-d]pyrimidine derivatives to obtain highly potent and selective antagonists for the human A3 adenosine receptor

In previous research, we identified some 7-oxo- and 7-acylamino-substituted pyrazolo[4,3-d]pyrimidine derivatives as potent and selective human (h) A3 adenosine receptor (AR) antagonists. Herein we report on the structural refinement of this class of antagonists aimed at achieving improved receptor-ligand recognition. Hence, substituents with different steric bulk, flexibility and lipophilicity (Me, Ar, heteroaryl, CH2Ph) were introduced at the 5- and 2-positions of the bicyclic scaffold of both the 7-oxo and 7-amino derivatives, and acyl residues were appended on the 7-amino group of the latter. All the 2-phenylpyrazolo[4,3-d]pyrimidin-7-amines and 7-acylamines bearing a 4-methoxyphenyl- or a 2-thienyl group at the 5-position showed high hA3 affinity and selectivity. In particular, the 2-phenyl-5-(2-thienyl)-pyrazolo[4,3-d]pyrimidin-7-(4-methoxybenzoyl)amine 25 (Ki = 0.027 nM) is one of the most potent and selective hA3 antagonists reported so far. By using an in silico receptor-driven approach the obtained binding data were rationalized and the molecular bases of the observed hA3 AR affinities were critically described.

Copper triflate-mediated synthesis of 1,3,5-triarylpyrazoles in [bmim][PF6] ionic liquid and evaluation of their anticancer activities

A simple, efficient, and environment friendly protocol for the synthesis of 1,3,5-triarylpyrazole and 1,3,5-triarylpyrazolines in [bimm][PF₆] ionic liquid mediated by Cu(OTf)₂ is described. The reaction protocol gave 1,3,5-triarylpyrazoles in good to high yields (71-84%) via a one-pot addition-cyclocondensation between chalcones and arylhydrazines, and oxidative aromatization without requirement for an additional oxidizing reagent. The catalyst can be reused up to four cycles without much loss in the catalytic activity. The pyrazoles (4a-o) and pyrazolines (3a-n) were evaluated for antiproliferative activity in SK-OV-3, HT-29, and HeLa human cancer cells lines. Among all compounds, 3b inhibited cell proliferation of HeLa cells by 80% at a concentration of 50 μM.

Gold-catalyzed three-component annulation: efficient synthesis of highly functionalized dihydropyrazoles from alkynes, hydrazines, and aldehydes or ketones

Polysubstituted dihydropyrazoles were directly obtained by a gold-catalyzed three-component annulation. This reaction consists of a Mannich-type coupling of alkynes with N,N'-disubstituted hydrazines and aldehydes/ketones followed by intramolecular hydroamination. Cascade cyclization using 1,2-dialkynylbenzene derivatives as the alkyne component was also performed producing fused tricyclic dihydropyrazoles in good yields.