Pyrido[2,3-d]pyrimidine-2,4(1H,3H)-dione derivatives as RAF-MEK-ERK pathway signaling pathway blockers: Synthesis, cytotoxic activity, mechanistic investigation and structure-activity relationships.

The constitutive activation of ERK1/2 (RAF-MEK-ERK) signaling pathway has been widely observed in many types of tumors, and the blockade of ERK1/2 signaling pathway has been proved to reduce tumor growth. Therefore, ERK1/2 signaling pathway has become an interesting therapeutic target for cancer therapy. Despite the successful development of BRAF and MEK inhibitors in clinic treatment, resistance often appears to re-enhance ERK1/2 signaling. Here we report the design, synthesis, biological activity of a series of novel pyrido[2,3-d]pyrimidine-2,4(1H,3H)-dione derivatives based on compound 1. Among them, the target compound N-(3-chlorophenyl)-2-((1,3-dimethyl-7-(4-methylpiperazin-1-yl)-2,4-dioxo-1,2,3,4-tetrahydropyrido[2,3-d]pyrimidin-5-yl)amino)acetamide (14m) exhibited excellent antiproliferative activity towards MCF-7, A375, SK-MEL-2 and SK-HEP-1 cells, with low cytotoxicity in C28/I2 cells. Tumor spheroid assay demonstrated the superior potency of 14m in inhibiting the growth of SK-HEP-1 spheroidal models. The mechanism of 14m to induce cancer cell death was shown to suppress cell migrations, induce cell apoptosis, decrease the levels of phosphorylated ERK and MEK in a dose-dependent manner and increase ROS production.

Design, Synthesis and Anticancer Activity of a New Series of N-aryl-N'-[4-(pyridin-2-ylmethoxy)benzyl]urea Derivatives.

The development of cancer treatments requires continuous exploration and improvement, in which the discovery of new drugs for the treatment of cancer is still an important pathway. In this study, based on the molecular hybridization strategy, a new structural framework with an N-aryl-N'-arylmethylurea scaffold was designed, and 16 new target compounds were synthesized and evaluated for their antiproliferative activities against four different cancer cell lines A549, MCF7, HCT116, PC3, and human liver normal cell line HL7702. The results have shown seven compounds with 1-methylpiperidin-4-yl groups having excellent activities against all four cancer cell lines, and they exhibited scarcely any activities against HL7702. Among them, compound 9b and 9d showed greatly excellent activity against the four kinds of cells, and the IC50 for MCF7 and PC3 cell lines were even less than 3 µM.

Synthesis and biological evaluation of a new series of 1-aryl-3-[4-(pyridin-2-ylmethoxy)phenyl]urea derivatives as new anticancer agents.

The diaryl ureas are very important fragments in medicinal chemistry. By means of computer-aided design, 1-aryl-3-[4-(pyridin-2-ylmethoxy)phenyl]urea derivatives were designed and synthesized, and evaluated for their antiproliferative activity against A549, HCT-116, PC-3 cancer cell lines, and HL7702 human normal liver cell lines in vitro by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric assay. Most of the target compounds demonstrate significant antiproliferative effects on all the selective cancer cell lines. The calculated IC50 values were reported. The target compound 1-(4-chlorophenyl)-3-{4-{[3-methyl-4-(2,2,2-trifluoroethoxy)pyridin-2-yl]methoxy}phenyl}urea (7u) demonstrated the most potent inhibitory activity (IC50 = 2.39 ± 0.10 µM for A549 and IC50 = 3.90 ± 0.33 µM for HCT-116), comparable to the positive-control sorafenib (IC50 = 2.12 ± 0.18 µM for A549 and IC50 = 2.25 ± 0.71 µM for HCT-116). Conclusively, 1-aryl-3-[4-(pyridin-2-ylmethoxy)phenyl]urea derivatives as the new anticancer agents were discovered, and could be used as the potential BRAF inhibitors for further research.

Structure-based virtual screening of influenza virus RNA polymerase inhibitors from natural compounds: Molecular dynamics simulation and MM-GBSA calculation.

The resistances of matrix protein 2 (M2) protein inhibitors and neuraminidase inhibitors for influenza virus have attracted much attention and there is an urgent need for new drug. The antiviral drugs that selectively act on RNA polymerase are less prone to resistance and possess fewer side effects on the patient. Therefore, there is increased interest in screening compounds that can inhibit influenza virus RNA polymerase. Three natural compounds were found by using molecular docking-based virtual screening, which could bind tightly within the polymerase acidic protein-polymerase basic protein 1 (PA-PB1) subunit of influenza virus polymerase. Firstly, their drug likeness properties were evaluated, which showed that the hepatotoxicity values of all the three compounds indicating they had less or no hepatotoxicity, and did not have the plasma protein biding (PPB) ability, the three compounds needed to be modified in some aspects, like bulky molecular size. The stability of the complexes of PA-hits was validated through molecular dynamics (MD) simulation, revealing compound 2 could form more stable complex with PA subunit. The torsional conformations of each rotatable bond of the ligands in PA subunit were also monitored, to investigate variation in the ligand properties during the simulation, compound 3 had fewer rotatable bonds, indicating that the molecule had stronger rigidity. The bar charts of protein-ligand contacts and contacts over the course of trajectory showed that four key residues (Glu623, Lys643, Asn703 and Trp706) of PA subunit that participated in hydrogen-bond, water bridge and hydrophobic interactions with the hit compounds. Finally, the binding free energy and contributed energies were calculated by using MM-GBSA method. Out of the three compounds, compound 1 showed the lowest total binding free energy. Among all the interactions, the contribution of the covalent binding and the van der Waals energy were more than other items, compound 1 formed more stable hydrogen bonds with the residues of PA subunit binding pocket. This study smoothed the path for the development of novel lead compounds with improved binding properties, high drug likeness, and low toxicity to humans for the treatment of influenza, which provided a good basis for further research on novel and effective influenza virus PA-PB1 interaction inhibitors.