Synthesis, Structure, and Antiproliferative Action of 2-Pyridyl Urea-Based Cu(II) Complexes

Differentiating Isomeric Urea Derivatives by Cyclic Ion Mobility-Mass Spectrometry, Host-Guest Chemistry, and Tandem Mass Spectrometry

Alkyl pyridyl ureas are crucial precursors in medicinal and agricultural chemistry. Their isomeric forms, which are distinguished by the position of pyridyl nitrogen relative to the urea functionality, pose challenges in mass spectrometric identification due to their isobaric molecular ions. This study presents orthogonal methods to differentiate 1-phenyl-3-(2-pyridyl) urea (ortho), 1-phenyl-3-(3-pyridyl) urea (meta), and 1-phenyl-3-(4-pyridyl) urea (para). Cyclic ion mobility separation of protonated molecules and their complexes with β-cyclodextrin was employed. While the protonated ortho and para isomers were baseline resolved after six passes, the meta and para isomers were not separated after 40 passes. After complexation with β-cyclodextrin, we observed two peaks for each isomer. The peak that arrived first (peak A) is a doubly protonated dimer of the host-guest complex, while the later arriving peak (peak B) corresponds to the singly protonated host-guest complex. Peak B for the β-cyclodextrin complex of the meta and para compounds was resolved after three passes. Thus, the differentiation of meta and para isomers was achieved after complexation with β-cyclodextrin. Overall, the two methods (ion mobility of protonated molecules and ion mobility of host-guest complexes) led to orthogonal results. Collision-induced dissociation of protonated molecules revealed identical fragment ions at m/z 95 and 121, but their relative intensities varied among isomers, enabling their clear differentiation. Additionally, collision-induced dissociation of host-guest complexes at 20 eV shows that the meta isomer forms the most stable complex with β-cyclodextrin and the para isomer forms the least stable complex, which provides additional orthogonal information to differentiate the three isomers. These findings provide a basis for cyclic traveling wave ion mobility and tandem mass spectrometry-based identification and characterization of other isomeric phenyl pyridyl ureas.

Synthesis of 3-(Pyridin-2-yl)quinazolin-2,4(1H,3H)-diones via Annulation of Anthranilic Esters with N-pyridyl Ureas

A new route for the synthesis of quinazolin-2,4(1H,3H)-diones and thieno [2,3-d]pyrimidine-2,4(1H,3H)-diones substituted by pyridyl/quinolinyl moiety in position 3 has been developed. The proposed method concluded in an annulation of substituted anthranilic esters or 2-aminothiophene-3-carboxylates with 1,1-dimethyl-3-(pyridin-2-yl) ureas. The process consists of the formation of N-aryl-N'-pyridyl ureas followed by their cyclocondensation into the corresponding fused heterocycles. The reaction does not require the use of metal catalysts and proceeds with moderate to good yields (up to 89%). The scope of the method is more than 30 examples, including compounds with both electron-withdrawing and electron-donating groups, as well as diverse functionalities. At the same time, strong electron-acceptor substituents in the pyridine ring of the starting ureas reduce the product yield or even prevent the cyclocondensation step. The reaction can be easily scaled to gram quantities.

Cytotoxicity and mechanism of action of metal complexes: An overview

After the discovery of cisplatin, many metal compounds were investigated for the therapy of diseases, especially cancer. The high therapeutic potential of metal-based compounds is related to the special properties of these compounds, such as their redox activity and ability to target vital biological sites. The overproduction of ROS and the consequent destruction of the membrane potential of mitochondria and/or the DNA helix is one of the known pathways leading to the induction of apoptosis by metal complexes. The apoptosis process can occur via the death receptor pathway and/or the mitochondrial pathway. The expression of Bcl2 proteins and the caspase family play critical roles in these pathways. In addition to apoptosis, autophagy is another process that regulates the suppression or promotion of various cancers through a dual action. On the other hand, the ability to interact with DNA is an important property found in several metal complexes with potent antiproliferative effects against cancer cells. These interactions were classified into two important categories: covalent/coordinated or subtle, and non-coordinated interactions. The anticancer activity of metal complexes is sometimes achieved by the simultaneous combination of several mechanisms. In this review, the anticancer effect of metal complexes is mechanistically discussed by different pathways, and some effective agents on their antiproliferative properties are explained.

Palladium(II) and Platinum(II) Deprotonated Diaminocarbene Complexes Based on N-(2-Pyridyl)ureas with Oxadiazole Periphery

Metal mediated coupling of isocyanides with substituted N-(pyridine-2-yl) ureas was first used to incorporate privileged biological motifs into platinum metal complexes. We synthesized two palladium(II) and two platinum(II) cyclometallated species with oxadiazole cores. The compounds were isolated in good yields (61–73%) and characterized by high-resolution mass spectrometry and 1H, 13C, and 195Pt NMR spectroscopies. The structures of three complexes were additionally elucidated by X-ray diffraction analysis. These complexes indeed showed cytotoxic activity. The species bearing the 1,3,4-oxadiazole moiety exhibit more potency than the ones with the 1,2,4-oxadiazole ring. Particularly, the cytotoxic effect of both 1,3,4-oxadiazole-based complexes towards T98G cells significantly exceeds the common antitumor metal-drug cisplatin.

Fumarato and Phthalato Bridged Dinuclear Metal-Organic Cu(II) and Mn(II) Compounds involving Infinite Fumarate-water Assemblies and Unusual Structure-guiding H-bonded Synthons: Antiproliferative Evaluation and Theoretical Studies

Two new dinuclear coordination compounds viz. [Cu2(µ-fum)(phen)2(H2O)6](fum)•6H2O (1) and [Mn2(µ-phth)2(phen)4]•2H2O (2) (phen = 1,10-phenanthroline, fum = fumarate and phth = phthalate) have been synthesized and characterized by elemental analysis, single...