Design and optimization of novel 4-(2-fluorophenoxy)quinoline derivatives bearing a hydrazone moiety as c-Met kinase inhibitors

Structure-guided design and development of novel N-phenylpyrimidin-2-amine derivatives as potential c-Met inhibitors

The HGF/Met signaling pathway is over-expressed in many types of cancers and closely related to oncogenesis and metastasis. Thus, we developed novel N-phenylpyrimidin-2-amine derivatives to test their inhibitory activities towards c-Met kinase, and most of the compounds (15a-i, 15o-r, 20 and 34a-c) could inhibit the target with IC₅₀ values from 550.8 nM to 15.0 nM. Subsequently, compound 15b, 15d, 15f, 15i, 15o, 15r, 20, 34a and 34b also showed high antiproliferative activities in c-Met sensitive tumor cell lines (PC-3, Panc-1, HepG2, HCT116 and Caki-1) with IC₅₀ values from 0.53 to 1.37 μM. The lead compound 34a displayed outstanding c-Met inhibitory activity (IC₅₀: 15.0 nM) and antiproliferative activities. Furthermore, 34a also performed favorable pharmacokinetic properties in mice (F%: 59.3) and an acceptable safety profile in preclinical studies. Further docking studies showed a common interaction of 34a with c-Met at the ATP-binding site, which indicated that 34a could be a potential candidate for c-Met inhibitors.

Quinoline-Based Molecules Targeting c-Met, EGF, and VEGF Receptors and the Proteins Involved in Related Carcinogenic Pathways

The quinoline ring system has long been known as a versatile nucleus in the design and synthesis of biologically active compounds. Currently, more than one hundred quinoline compounds have been approved in therapy as antimicrobial, local anaesthetic, antipsychotic, and anticancer drugs. In drug discovery, indeed, over the last few years, an increase in the publication of papers and patents about quinoline derivatives possessing antiproliferative properties has been observed. This trend can be justified by the versatility and accessibility of the quinoline scaffold, from which new derivatives can be easily designed and synthesized. Within the numerous quinoline small molecules developed as antiproliferative drugs, this review is focused on compounds effective on c-Met, VEGF (vascular endothelial growth factor), and EGF (epidermal growth factor) receptors, pivotal targets for the activation of important carcinogenic pathways (Ras/Raf/MEK and PI3K/AkT/mTOR). These signalling cascades are closely connected and regulate the survival processes in the cell, such as proliferation, apoptosis, differentiation, and angiogenesis. The antiproliferative biological data of remarkable quinoline compounds have been analysed, confirming the pivotal importance of this ring system in the efficacy of several approved drugs. Furthermore, in view of an SAR (structure-activity relationship) study, the most recurrent ligand–protein interactions of the reviewed molecules are summarized.

Design, synthesis and biological evaluation of novel (E)-N-phenyl-4-(pyridine-acylhydrazone) benzamide derivatives as potential antitumor agents for the treatment of multiple myeloma (MM)

A series of novel (E)-N-phenyl-4-(pyridine-acylhydrazone) benzamide derivatives were designed, synthesized, and evaluated for their anti-proliferative activity against two different human cancer cell lines and one human normal cell line. Compound 8b had the best anti-proliferative activity (IC₅₀ = 0.12 ± 0.09 μM, RPMI8226 cells) than the other compounds. And compound 8b had lower toxicity than imatinib. Flow cytometry analysis showed that compound 8b could arrest the cell cycle at the G0/G1 phase, and induce apoptosis of RPMI8226 cells by promoting mitochondrial ROS release, thereby effectively inhibiting cell proliferation. Our findings provided a promising lead compound 8b for further structural optimization and will be instructive for the discovery of more potent antitumor drugs with high selectivity and low toxicity.

Synthesis and Structure Insights of Two Novel Broad-Spectrum Antibacterial Candidates Based on (E)-N'-[(Heteroaryl)methylene]adamantane-1-carbohydrazides

Two new N′-heteroarylidene-1-carbohydrazide derivatives, namely; E-N′-[(pyridine-3-yl)methylidene]adamantane-1-carbohydrazide (1) and E-N′-[(5-nitrothiophen-2-yl)methylidene]adamantane-1-carbohydrazide (2), were produced via condensation of adamantane-1-carbohydrazide with the appropriate heterocyclic aldehyde. Both compounds were chemically and structurally characterized by ¹H-NMR, ¹³C-NMR, infrared and UV-vis spectroscopies, and single crystal X-ray diffraction. The study was complemented with density functional theory calculations (DFT). The results show an asymmetrical charge distribution in both compounds, with the electron density accumulated around the nitrogen and oxygen atoms, leaving the positive charge surrounding the N-H and C-H bonds in the hydrazine group. Consequently, the molecules stack in an antiparallel fashion in the crystalline state, although the contribution of the polar contacts to the stability of the lattice is different for 1 (18%) and 2 (42%). This difference affects the density and symmetry of their crystal structures. Both molecules show intense UV-Vis light absorption in the range 200–350 nm (1) and 200–500 nm (2), brought about by π → π* electronic transitions. The electron density difference maps (EDDM) revealed that during light absorption, the electron density flows within the π-delocalized system, among the pyridyl/thiophene ring, the nitro group, and the N′-methyleneacetohydrazide moiety. Interestingly, compounds 1 and 2 constitute broad-spectrum antibacterial candidates, displaying potent antibacterial activity with minimal inhibitory concentration (MIC) values around 0.5–2.0 μg/mL. They also show weak or moderate antifungal activity against the yeast-like pathogenic fungus Candida albicans.

Design, synthesis, and biological evaluation of 4-((6,7-dimethoxyquinoline-4-yl)oxy)aniline derivatives as FLT3 inhibitors for the treatment of acute myeloid leukemia

FMS-like tyrosine kinase 3 (FLT3) was an important therapeutic target in acute myeloid leukemia (AML). We synthesized two series of 4-((6,7-dimethoxyquinoline-4-yl)oxy)aniline derivatives possessing the semicarbazide moiety and 2,2,2-trifluoro-N,N'-dimethylacetamide moiety as the linker. The cell proliferation assay in vitro against HL-60 and MV4-11 cell lines demonstrated that most series I compounds containing semicarbazide moiety had more potent than Cabozantinib. Furthermore, the enzyme assay showed that compound 12c and 12g were potent FLT3 inhibitors with IC₅₀ values of 312 nM and 384 nM, respectively. Following that, molecular docking analysis was also performed to determine possible binding mode between FLT3 and the target compound.

Discovery of novel 1,2,4-triazolo-1,2,4-triazines with thiomethylpyridine hinge binders as potent c-Met kinase inhibitors

Aim: Mesenchymal-epithelial transition factor (c-Met)/HGF overactivation is involved in diverse human cancers. Materials & methods: Herein, we report the synthesis and biological evaluation of thiomethylpyridine-linked triazolotriazines as c-Met kinase inhibitors. Results: Compounds 10b and 11e were more potent than crizotinib on HepG2 cells with IC₅₀ values of 0.74 and 0.71 μM in the MTT assay, respectively. Interestingly, all of the target compounds displayed IC₅₀ values in the range of 3.9-11.1 nM in the c-Met kinase inhibition assay which were lower than the value for crizotinib (11.1 nM). Conclusion: Target compound 10b can be considered as a leading drug candidate due to its lower IC₅₀ values than crizotinib in both HGF-induced proliferation and c-Met kinase inhibition assays.

Development of efficient docking strategies and structure-activity relationship study of the c-Met type II inhibitors

c-Met is a transmembrane receptor tyrosine kinase and an important therapeutic target for anticancer drugs. In the present study, we systematically investigated the influence of a range of parameters on the correlation between experimental and calculated binding free energies of type II c-Met inhibitors. We especially focused on evaluating the impact of different force fields, binding energy calculation methods, docking protocols, conformation sampling strategies, and conformations of the binding site captured in several crystallographic structures. Our results suggest that the force fields, the protein flexibility, and the selected conformation of the binding site substantially influence the correlation coefficient, while the sampling strategies and ensemble docking only mildly affect the prediction accuracy. Structure-activity relationship study suggests that the structural determinants to the high binding affinity of the type II inhibitors originate from its overall linear shape, hydrophobicity, and two conserved hydrogen bonds. Results from this study will form the basis for establishing an efficient computational docking approach for c-Met type II inhibitors design.

Crystal structure of N′-(adamantan-2-ylidene)pyridine-3-carbohydrazide, C16H19N3O

C16H19N3O, orthorhombic, Pna21 (no. 33), a = 8.0381(5) Å, b = 10.4499(8) Å, c = 17.1228(13) Å, V = 438.27(18) Å, Z = 4, Rgt(F) = 0.0499, wRref(F2) = 0.1105, T = 100 K.

Design, Synthesis and Evaluation of Antiproliferative Activity of New Benzimidazolehydrazones

The synthesis and antiproliferative activity of new benzimidazole derivatives bearing an hydrazone mojety at the 2-position is described. The new N′-(4-arylidene)-1H-benzo[d]imidazole-2-carbohydrazides were evaluated for their cytostatic activity toward the murine leukemia (L1210), human T-cell leukemia (CEM), human cervix carcinoma (HeLa) and human pancreas carcinoma cells (Mia Paca-2). A preliminary structure-activity relationship could be defined. Some of the compounds possess encouraging and consistent antiproliferative activity, having IC₅₀ values in the low micromolar range.