New 2-alkoxycyanopyridine derivatives as inhibitors of EGFR, HER2, and DHFR: Synthesis, anticancer evaluation, and molecular modeling studies

New series of substituted 2-alkoxycyanopyridine derivatives were synthesized and evaluated for their in vitro and in vivo anticancer activities. Comparing the evaluated activities against cancer cell lines to the broad-spectrum anticancer doxorubicin, and the kinase inhibitor sorafenib, compounds 3a, 4b, 4c, 7a, and 8d demonstrated superior anticancer efficacy with elevated safety profiles and selectivity indices, particularly against MCF7 breast cancer. For exploration of their mechanism of action, assays for inhibition of EGFR, HER2 kinase, and DHFR were performed. The promising synthesized compounds exhibited potent dual kinase EGFR/HER2 inhibitory activity with IC50values of 0.248/0.156 μM for 4b and 0.138/0.092 μM for 4c. Additionally, with IC50 values of 0.138 and 0.193 M, respectively, 4b and 4c had the greatest DHFR inhibitory activity that was comparable to methotrexate. In the MCF7 breast cancer cell line, they caused arrest at the S phase of the cell cycle and exhibited apoptosis induction activity. With restored caspase-3 immunoexpression, the anti-breast cancer assay performed in vivo of 4b and 4c demonstrated a substantial decrease in tumor volume. Results from molecular modeling were in agreement with biological assays proving the importance of the 3-caynopyridine, two substituted phenyl rings attached to central pyridine ring, and propoxy side chain moieties for binding with the receptors. As 4c works by inhibiting both EGFR/HER2 kinase, DHFR enzymes, in addition to cellular apoptosis, it could be viewed as a model of compounds possessing a multi-targeting anticancer activity. Collectively, compounds 4b and 4c might represent prototypes for further development as anticancer molecules.

Thiazole: A Versatile Standalone Moiety Contributing to the Development of Various Drugs and Biologically Active Agents

For many decades, the thiazole moiety has been an important heterocycle in the world of chemistry. The thiazole ring consists of sulfur and nitrogen in such a fashion that the pi (π) electrons are free to move from one bond to other bonds rendering aromatic ring properties. On account of its aromaticity, the ring has many reactive positions where donor–acceptor, nucleophilic, oxidation reactions, etc., may take place. Molecules containing a thiazole ring, when entering physiological systems, behave unpredictably and reset the system differently. These molecules may activate/stop the biochemical pathways and enzymes or stimulate/block the receptors in the biological systems. Therefore, medicinal chemists have been focusing their efforts on thiazole-bearing compounds in order to develop novel therapeutic agents for a variety of pathological conditions. This review attempts to inform the readers on three major classes of thiazole-bearing molecules: Thiazoles as treatment drugs, thiazoles in clinical trials, and thiazoles in preclinical and developmental stages. A compilation of preclinical and developmental thiazole-bearing molecules is presented, focusing on their brief synthetic description and preclinical studies relating to structure-based activity analysis. The authors expect that the current review may succeed in drawing the attention of medicinal chemists to finding new leads, which may later be translated into new drugs.