Design, Synthesis, Molecular Modeling, and Biological Evaluation of Novel Pyrimidine Derivatives as Potential Calcium Channel Blockers.

Pyrimidines play an important role in modern medical fields. They have a wide spectrum of biological activities such as antimicrobial, anticancer, anti-allergic, anti-leishmanial, antioxidant agents and others. Moreover, in recent years, 3,4-dihydropyrimidin-2(1H)ones have attracted researchers to synthesize them via Biginelli reaction and evaluate their antihypertensive activities as bioisosters of Nifedipine, which is a famous calcium channel blocker. Our new target compounds were prepared through one-pot reaction of thiourea 1, ethyl acetoacetate 2 and/or 1H-indole-2-carbaldehyde, 2-chloroquinoline-3-carbaldehyde, 1,3-diphenyl-1H-pyrazole-4-carbaldehyde, 3a-c in acid medium (HCl) yielding pyrimidines 4a-c, which in turn were hydrolyzed to carboxylic acid derivatives 5a-c which were chlorinated by SOCl2 to give acyl chlorides 6a-c. Finally, the latter were reacted with some selected aromatic amines, namely, aniline, p-toluidine and p-nitroaniline, producing amides 7a-c, 8a-c, and 9a-c. The purity of the prepared compounds was examined via TLC monitoring, and structures were confirmed by different spectroscopic techniques such as IR, 1HNMR, 13CNMR, and mass spectroscopy. The in vivo evaluation of the antihypertensive activity revealed that compounds 4c, 7a, 7c, 8c, 9b and 9c had comparable antihypertensive properties with Nifedipine. On the other hand, the in vitro calcium channel blocking activity was evaluated by IC50 measurement and results revealed that compounds 4c, 7a, 7b, 7c, 8c, 9a, 9b, and 9c had comparable calcium channel blocking activity with the reference Nifedipine. Based on the aforementioned biological results, we selected compounds 8c and 9c to be docked onto Ryanodine and dihydropyridine receptors. Furthermore, we developed a structure-activity relationship. The designed compounds in this study show promising activity profiles in reducing blood pressure and as calcium channel blockers, and could be considered as new potential antihypertensive and/or antianginal agents.

Synthesis of Dihydropyrimidines: Isosteres of Nifedipine and Evaluation of Their Calcium Channel Blocking Efficiency.

Hypertension and cardiovascular diseases related to it remain the leading medical challenges globally. Several drugs have been synthesized and commercialized to manage hypertension. Some of these drugs have a dihydropyrimidine skeleton structure, act as efficient calcium channel blockers, and affect the calcium ions' intake in vascular smooth muscle, hence managing hypertension. The synthesis of such moieties is crucial, and documenting their structure-activity relationship, their evolved and advanced synthetic procedures, and future opportunities in this area is currently a priority. Tremendous efforts have been made after the discovery of the Biginelli condensation reaction in the synthesis of dihydropyrimidines. From the specific selection of Biginelli adducts to the variation in the formed intermediates to achieve target compounds containing heterocylic rings, aldehydes, a variety of ketones, halogens, and many other desired functionalities, extensive studies have been carried out. Several substitutions at the C3, C4, and C5 positions of dihydropyrimidines have been explored, aiming to produce feasible derivatives with acceptable yields as well as antihypertensive activity. The current review aims to cover this requirement in detail.

Synthesis, biological evaluation and molecular docking studies of novel thiopyrimidine analogue as apoptotic agent with potential anticancer activity.

This study synthesizes novel 6-amino-5-cyano-4-aryl-2-mercapto pyrimidines and condensed pyrimidines analogues in order to investigate their potential activity as anticancer agents. The compounds were synthesized via one-pot condensation of p-nitrobenzaldehyde or p-anisaldehyde with malononitrile and thiourea to prepare 6-amino-5-cyano-4-aryl-2-mercaptopyrimidines series (1-9a,b). The pyrimidine analogues were biologically screened In-vitro in HepG2 and MCF-7 compared to normal WI-38. Compound 8a showed higher antiproliferative activity to MCF-7 cells with sensitivity and minimal cytotoxic effect (IC50 53.3 µM- HepG2, 12.9 µM- MCF-7 and >100 µM- WI-38). Compound 8a was able to induce 40% of total antioxidants and 60% following treatment with 50 µM of H2O2 for 3hrs as external source of oxidative stress in MCF-7. 8a was able to significantly induce early stage apoptosis of 74.37% MCF-7 and cell cycle arrest with cells accumulation in subG0-G1 phase to 69.42% and reduction of cells in G2M phase to 3.6% and high apoptotic index. Compound 8a induced over-expression of Fas receptor and Cyto C genes. Molecular docking studies suggested that 8a can bind to both phosphodiesterase 4B and 4D binding pockets and inhibit their action through network of hydrophobic interactions in Q-P pockets with preferential selectivity to PDE4B through invariant Glu443. The chemical profile and the biological results suggest that 8a can be a promising anticancer agent.

Design, Synthesis, Molecular Modeling, and Biological Evaluation of Novel Thiouracil Derivatives as Potential Antithyroid Agents.

Hyperthyroidism is the result of uncontrolled overproduction of the thyroid hormones. One of the mostly used antithyroid agents is 6-n-propyl-2-thiouracil (PTU). The previously solved X-ray crystal structure of the PTU bound to mammalian lactoperoxidase (LPO) reveals that the LPO-PTU binding site is basically a hydrophobic channel. There are two hydrophobic side chains directed towards the oxygen atom in the C-4 position of the thiouracil ring. In the current study, the structural activity relationship (SAR) was performed on the thiouracil nucleus of PTU to target these hydrophobic side chains and gain more favorable interactions and, in return, more antithyroid activity. Most of the designed compounds show superiority over PTU in reducing the mean serum T4 levels of hyperthyroid rats by 3% to 60%. In addition, the effect of these compounds on the levels of serum T3 was found to be comparable to the effect of PTU treatment. The designed compounds in this study showed a promising activity profile in reducing levels of thyroid hormones and follow up experiments will be needed to confirm the use of the designed compounds as new potential antithyroid agents.