Visible-Light-Induced Synthesis of Branched Ethers via Multicomponent Reactions.

The Spin-Center Shift (SCS) elimination is a specific way for the generation of radicals with relevance in synthetic and biochemical pathways. The combination of SCS-mediated radical chemistry and atom-transfer radical addition (ATRA) offers new directions in diversity-oriented chemical synthesis. Herein, we report a photoredox three-component reaction of α-acyloxy-N-heterocycles as radical precursors, styrene derivatives as radical trapping agents, and alcohols as nucleophilic quenchers. The novel radical-polar crossover reaction provides access to a diverse set of branched ethers possessing high structural complexity. The utility of the transformation was also demonstrated by the synthesis of a complex drug derivative and it was easily scalable to the multigram level. The scope and limitations were also explored and a plausible mechanism was proposed.

Enantioselective Synthesis of 8-Hydroxyquinoline Derivative, Q134 as a Hypoxic Adaptation Inducing Agent.

Hypoxia is a common feature of neurodegenerative diseases, including Alzheimer's disease that may be responsible for disease pathogenesis and progression. Therefore, the hypoxia-inducible factor (HIF)1 system, responsible for hypoxic adaptation, is a potential therapeutic target to combat these diseases by activators of cytoprotective protein induction. We have selected a candidate molecule from our cytoprotective hydroxyquinoline library and developed a novel enantioselective synthesis for the production of its enantiomers. The use of quinidine or quinine as a catalyst enabled the preparation of enantiomer-pure products. We have utilized in vitro assays to evaluate cytoprotective activity, a fluorescence-activated cell sorting (FACS) based assay measuring mitochondrial membrane potential changes, and gene and protein expression analysis. Our data showed that the enantiomers of Q134 showed potent and similar activity in all tested assays. We have concluded that the enantiomers exert their cytoprotective activity via the HIF1 system through HIF1A protein stabilization.

Synthesis and Cytoprotective Characterization of 8-Hydroxyquinoline Betti Products.

The 8-hydroxyquinoline pharmacophore scaffold has been shown to possess a range of activities as metal chelation, enzyme inhibition, cytotoxicity, and cytoprotection. Based on our previous findings we set out to optimize the scaffold for cytoprotective activity for its potential application in central nervous system related diseases. A 48-membered Betti-library was constructed by the utilization of formic acid mediated industrial-compatible coupling with sets of aromatic primary amines such as anilines, oxazoles, pyridines, and pyrimidines, with (hetero)aromatic aldehydes and 8-hydroxiquinoline derivatives. After column chromatography and re-crystallization, the corresponding analogues were obtained in yields of 13⁻90%. The synthesized analogs were optimized with the utilization of a cytoprotection assay with chemically induced oxidative stress, and the most active compounds were further tested in orthogonal assays, a real time cell viability method, a fluorescence-activated cell sorting (FACS)-based assay measuring mitochondrial membrane potential changes, and gene expression analysis. The best candidates showed potent, nanomolar activity in all test systems and support the need for future studies in animal models of central nervous system (CNS) disorders.

Synthesis, cytotoxic characterization, and SAR study of imidazo[1,2-b]pyrazole-7-carboxamides.

The synthesis and in vitro cytotoxic characteristics of new imidazo[1,2-b]pyrazole-7-carboxamides were investigated. Following a hit-to-lead optimization exploiting 2D and 3D cultures of MCF-7 human breast, 4T1 mammary gland, and HL-60 human promyelocytic leukemia cancer cell lines, a 67-membered library was constructed and the structure-activity relationship (SAR) was determined. Seven synthesized analogues exhibited sub-micromolar activities, from which compound 63 exerted the most significant potency with a remarkable HL-60 sensitivity (IC50 = 0.183 µM).

Mannich Curcuminoids as Potent Anticancer Agents.

A series of novel curcuminoids were synthesised for the first time via a Mannich-3CR/organocatalysed Claisen-Schmidt condensation sequence. Structure-activity relationship (SAR) studies were performed by applying viability assays and holographic microscopic imaging to these curcumin analogues for anti-proliferative activity against A549 and H1975 lung adenocarcinoma cells. The TNFα-induced NF-κB inhibition and autophagy induction effects correlated strongly with the cytotoxic potential of the analogues. Significant inhibition of tumour growth was observed when the most potent analogue 44 was added in liposomes at one-sixth of the maximally tolerated dose in the A549 xenograft model. The novel spectrum of activity of these Mannich curcuminoids warrants further preclinical investigations.

The Curcumin Analog C-150, Influencing NF-κB, UPR and Akt/Notch Pathways Has Potent Anticancer Activity In Vitro and In Vivo.

C-150 a Mannich-type curcumin derivative, exhibited pronounced cytotoxic effects against eight glioma cell lines at micromolar concentrations. Inhibition of cell proliferation by C-150 was mediated by affecting multiple targets as confirmed at transcription and protein level. C-150 effectively reduced the transcription activation of NFkB, inhibited PKC-alpha which are constitutively over-expressed in glioblastoma. The effects of C-150 on the Akt/ Notch signaling were also demonstrated in a Drosophila tumorigenesis model. C-150 reduced the number of tumors in Drosophila with similar efficacy to mitoxantrone. In an in vivo orthotopic glioma model, C-150 significantly increased the median survival of treated nude rats compared to control animals. The multi-target action of C-150, and its preliminary in vivo efficacy would render this curcumin analogue as a potent clinical candidate against glioblastoma.

Facile synthesis of 1H-imidazo[1,2-b]pyrazoles via a sequential one-pot synthetic approach.

5-Aminopyrazole-4-carbonitrile and ethyl 5-aminopyrazole-4-carboxylate, as potential trifunctional building blocks are introduced in a facile, chemo- and regioselective multicomponent assembly of imidazo[1,2-b]pyrazoles via the Groebke-Blackburn-Bienaymé reaction (GBB reaction). Besides the synthetic elaboration of a green-compatible isocyanide-based access in three-component mode, we describe an operationally simple, one-pot two-step GBB protocol for the rapid construction of a 46 membered imidazo[1,2-b]pyrazole library with yields up to 83%.

Synthesis of novel pyrazole-based heterocycles via a copper(II)-catalysed domino annulation.

Pyrazole-based ß-aminonitriles and ß-amino-carbaldehydes as bifunctional building blocks are introduced in a facile copper(II)-catalysed one-pot domino generation of multiple N-containing heterobi- and tricycles. This streamlined synthetic approach permits easy access to novel pyrazole-fused imidazo- and pyrimido[1,2-c]pyrimidinones and to pyrazolo[3,4-d]pyrimidinone species with isolated yields up to 90%. The present study also reveals a unique amine-isocyanate coupling promotion via copper(II)-based catalytic activation.

Q50, an iron-chelating and zinc-complexing agent, improves cardiac function in rat models of ischemia/reperfusion-induced myocardial injury.

BACKGROUND: Reperfusion of ischemic myocardium may contribute to substantial cardiac tissue damage, but the addition of iron chelators, zinc or zinc complexes has been shown to prevent heart from reperfusion injury. We investigated the possible beneficial effects of an iron-chelating and zinc-complexing agent, Q50, in rat models of ischemia/reperfusion (I/R)-induced myocardial infarction and on global reversible myocardial I/R injury after heart transplantation. METHODS AND RESULTS: Rats underwent 45-min myocardial ischemia by left anterior descending coronary artery ligation followed by 24h reperfusion. Vehicle or Q50 (10 mg/kg, IV) were given 5 min before reperfusion. In a heart transplantation model, donor rats received vehicle or Q50 (30 mg/kg, IV) 1h before the onset of ischemia. In myocardial infarcted rats, increased left ventricular end-systolic and end-diastolic volumes were significantly decreased by Q50 post treatment as compared with the sham group. Moreover, in I/R rat hearts, the decreased dP/dtmax and load-independent contractility parameters were significantly increased after Q50. However, Q50 treatment did not reduce infarct size or have any effect on increased plasma cardiac troponin-T-levels. In the rat model of heart transplantation, 1h after reperfusion, decreased left ventricular systolic pressure, dP/dt(max), dP/dt(min) and myocardial ATP content were significantly increased and myocardial protein expression of superoxide dismutase-1 was upregulated after Q50 treatment. CONCLUSIONS: In 2 experimental models of I/R, administration of Q50 improved myocardial function. Its mechanisms of action implicate in part the restoration of myocardial high-energy phosphates and upregulation of antioxidant enzymes.

Aromatic sulfonamides containing a condensed piperidine moiety as potential oxidative stress-inducing anticancer agents.

A 30-membered piperidine ring-fused aromatic sulfonamide library was synthetized, including N-arylsulfonyl 1,2,3,4-tetrahydroquinolines, 1,2,3,4-tetrahydroisoquinolines and 2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indoles. The compounds induced oxidative stress and glutathione depletion in HT168 melanoma and K562 leukemia cells and in micromolar concentrations exerted cytotoxic effects. Among the tested sulfonamides, compounds 21, 22, 23, 35 and 41 exhibited 100% cytotoxic effects with low (< 10 µM) EC50 values on K562 cells. The cytotoxicity of lead compound 22 was investigated in 24 different cancer cell lines, and it was found to be active against leukemia, melanoma, glioblastoma, and liver, breast and lung cancer cells, as confirmed by classical biochemical and holographic microscopic analyses.

Polyunsaturated fatty acids synergize with lipid droplet binding thalidomide analogs to induce oxidative stress in cancer cells.

BACKGROUND: Cytoplasmic lipid-droplets are common inclusions of eukaryotic cells. Lipid-droplet binding thalidomide analogs (2,6-dialkylphenyl-4/5-amino-substituted-5,6,7-trifluorophthalimides) with potent anticancer activities were synthesized. RESULTS: Cytotoxicity was detected in different cell lines including melanoma, leukemia, hepatocellular carcinoma, glioblastoma at micromolar concentrations. The synthesized analogs are non-toxic to adult animals up to 1 g/kg but are teratogenic to zebrafish embryos at micromolar concentrations with defects in the developing muscle. Treatment of tumor cells resulted in calcium release from the endoplasmic reticulum (ER), induction of reactive oxygen species (ROS), ER stress and cell death. Antioxidants could partially, while an intracellular calcium chelator almost completely diminish ROS production. Exogenous docosahexaenoic acid or eicosapentaenoic acid induced calcium release and ROS generation, and synergized with the analogs in vitro, while oleic acid had no such an effect. Gene expression analysis confirmed the induction of ER stress-mediated apoptosis pathway components, such as GADD153, ATF3, Luman/CREB3 and the ER-associated degradation-related HERPUD1 genes. Tumor suppressors, P53, LATS2 and ING3 were also up-regulated in various cell lines after drug treatment. Amino-phthalimides down-regulated the expression of CCL2, which is implicated in tumor metastasis and angiogenesis. CONCLUSIONS: Because of the anticancer, anti-angiogenic action and the wide range of applicability of the immunomodulatory drugs, including thalidomide analogs, lipid droplet-binding members of this family could represent a new class of agents by affecting ER-membrane integrity and perturbations of ER homeostasis.

A cell-microelectronic sensing technique for the screening of cytoprotective compounds.

In recent years, a new cell-based high throughput paradigm has emerged, which seeks to identify novel, pharmacologically active cytoprotective compounds. The essence of this approach is to create experimental models of cell injury relevant for a particular disease by establishing in vitro cell-based models, followed by high-throughput testing of compounds that affect the cellular response in a desired manner. Prior approaches typically used simple end-point analyses. To assess the cytoprotective effects of novel drug candidates in real-time, we have applied a cell-microelectronic sensing technique (RT-CES), which measures changes in the impedance of individual microelectronic wells that correlates linearly with cell index (reflecting cell number, adherence and cell growth), thereby allowing the continuous determination of cell viability during oxidative stress. In vitro cytotoxicity was elicited by hydrogen peroxide in myocytes (H9c2) and hepatocytes (Hep3B). Cells were post-treated at 30 min with various reference molecules and novel cytoprotective compounds. Cytoprotection detected in the RT-CES system correlated well with the results of two classical end-point-based methods (improvement in MTT and reduction of LDH release). The RT-CES method, when used as described in the current report, is suitable for the screening of molecular libraries to identify molecules or molecule combinations that attenuate oxidative stress-induced cell damage.