New hypotheses for the binding mode of 4- and 7-substituted indazoles in the active site of neuronal nitric oxide synthase

Using Metalloporphyrin Nanosensors for In Situ Monitoring and Measurement of Nitric Oxide and Peroxynitrite in a Single Human Neural Progenitor Cell

Nitric oxide (NO) is an inorganic signaling molecule that plays a crucial role in the regulation of numerous physiological functions. An oxidation product of the cytoprotective NO is cytotoxic peroxynitrite (ONOO-). In biological systems, the concentrations of NO and ONOO- are typically transient, ranging from nanomolar to micromolar, and these increases are normally followed by a swift return to their basal levels due to their short life spans. To understand the vital physiological role of NO and ONOO- in vitro and in vivo, sensitive and selective methods are necessary for direct and continuous NO and ONOO- measurements in real time. Because electrochemical methods can be adjusted for selectivity, sensitivity, and biocompatibility in demanding biological environments, they are suitable for real-time monitoring of NO and ONOO- release. Metalloporphyrin nanosensors, described here, have been designed to measure the concentration of NO and ONOO- produced by a single human neural progenitor cell (hNPC) in real time. These nanosensors (200-300 nm in diameter) can be positioned accurately in the proximity of 4-5 ± 1 μm from an hNPC membrane. The response time of the sensors is better than a millisecond, while detection limits for NO and ONOO- are 1 × 10-9 and 3 × 10-9 mol/L, respectively, with a linear concentration response of up to about 1 μM. The application of these metalloporphyrin nanosensors for the efficient measurement of the concentrations of NO and ONOO- in hNPCs is demonstrated, providing an opportunity to observe in real time the molecular changes of the two signaling molecules in situ.

TfOH-catalyzed regioselective N2-alkylation of indazoles with diazo compounds

Selective alkylation of indazoles is still a highly challenging topic in chemistry and the synthesis of important molecules. Herein, a novel highly selective N²-alkylation of indazoles with diazo compounds is described in the presence of TfOH. Unlike the traditional metal- and base-catalysed version, this protocol highlights the regioselectivity of alkylation of indazoles and a metal-free catalysis system, affording N²-alkylated products in good to excellent yields with high regioselectivity (N²/N¹ up to 100/0) and excellent functional group tolerance. Furthermore, a gram scale synthesis was conducted successfully to give rise to the corresponding products. Mechanistic studies through control experiments provide plausible mechanistic proposals.

A regioselective C7 bromination and C7 palladium-catalyzed Suzuki-Miyaura cross-coupling arylation of 4-substituted NH-free indazoles

A direct and efficient regioselective C7-bromination of 4-substituted 1H-indazole has been achieved. Subsequently, a successful palladium-mediated Suzuki–Miyaura reaction of C7-bromo-4-substituted-1H-indazoles with boronic acids has been performed under optimized reaction conditions. A series of new C7 arylated 4-substituted 1H-indazoles was obtained in moderate to good yields.

A regioselective C7-bromination of 4-substituted 1H-indazoles followed by a palladium-catalyzed Suzuki–Miyaura reaction with boronic acids is described.

Synthesis and Activity Evaluation of Nasopharyngeal Carcinoma Inhibitors Based on 6-(Pyrimidin-4-yl)-1H-indazole

Human nasopharyngeal carcinoma is a common head and neck malignancy with high incidence in Southeast Asia and Southern China. It is necessary to develop safe, effective and inexpensive anticancer agents to improve the therapeutics of patients with nasopharyngeal carcinoma. A series of small molecular compounds based on 6-(pyrimidin-4-yl)-1H-indazole were synthesized and evaluated for antiproliferative activities against human nasopharyngeal carcinoma cell lines SUNE1. Compounds 6b, 6c, 6e and 6l showed potent antiproliferative activities similar to positive control drug cisplatin in vitro with lower nephrotoxicity than it. N-[4-(1H-Indazol-6-yl)pyrimidin-2-yl]benzene-1,3-diamine (6l) was selected for further study. It was found that 6l induced mitochondria-mediated apoptosis and G₂ /M phase arrest in SUNE1 cells. Furthermore, compound 6l at 10 mg/kg can suppress the growth of an implanted SUNE1 xenograft with a TGI% (tumor growth inhibition) value of 50 % and did not cause serious side effects in BALB/c nude mice. This study suggests that 6-(pyrimidin-4-yl)-1H-indazole derivatives are a series of small molecule compounds with anti-nasopharyngeal carcinoma activities.

Synthesis, Crystal Structure and Antitumour Activity of 3-Amino-4-Morpholino-1H-Indazol-1-yl(3-Fluorophenyl)Methanone

3-Amino-4-morpholino-1H-indazol-1-yl(3-fluorophenyl)methanone was synthesised by condensation of 3-fluorobenzoic acid with 4-morpholino-1H-indazol-3-amine, which was prepared from 2,6-difluorobenzonitrile by amination with morpholine and then cyclisation with hydrazine hydrate. The molecular structure was tested by single crystal X-ray diffraction. Preliminary biological tests showed that the compound possesses distinct inhibition on the proliferation of A549, BGC-823 and HepG-2 cancer cell lines.

Synthesis, Crystal Structure and Antitumour Activity of 4-(3-Amino-4-Morpholino-1H-Indazole-1-Carbonyl)Benzonitrile

The title compound, 4-(3-amino-4-morpholino-1 H-indazole-1-carbonyl)benzonitrile was synthesised by condensation of 4-cyanobenzoic acid with 4-morpholino-1 H-indazol-3-amine, which was prepared from 2,6-difluorobenzonitrile by amination with morpholine and then cyclisation with hydrazine hydrate. The crystal structure of the title compound was determined and the crystals belong to the monoclinic system, space group P21/ c. In addition, the compound showed some inhibition of the proliferation of some cancer cell lines.

Regioselective synthesis of 2H-indazoles through Ga/Al- and Al-mediated direct alkylation reactions of indazoles

A procedure has been developed for the regioselective, high yielding synthesis of 2H-indazoles.

Ethyl 3-[7-(N-acetyl-4-meth-oxy-benzene-sulfonamido)-3-chloro-2H-indazol-2-yl]propionate

In the title compound, C21H22ClN3O6S, the fused five- and six-membered ring rings are almost perpendicular to the planes through the atoms forming the acetyl and the propionic ester groups, as indicated by the dihedral angles of 80.3 (2) and 88.3 (7)°, respectively. The dihedral angle between the indazole system and the 4-meth-oxy-benzene-sulfonyl group is 13.76 (6)°. The carbonyl O atom is split over two positions in a 0.60 (5):0.40 (5) ratio. In the crystal, mol-ecules are linked by C-H⋯O and C-H⋯N inter-actions into a three-dimensional network.