Dependence of the base sequence on the [Cu(2,2′-bipyridine)2(NO3)](NO3)-induced oxidative DNA cleavage probed by linear dichroism

Nuclease-like metalloscissors: Biomimetic candidates for cancer and bacterial and viral infections therapy

Despite the extensive and rapid discovery of modern drugs for treatment of cancer, microbial infections, and viral illnesses; these diseases are still among major global health concerns. To take inspiration from natural nucleases and also the therapeutic potential of metallopeptide antibiotics such as the bleomycin family, artificial metallonucleases with the ability of promoting DNA/RNA cleavage and eventually affecting cellular biological processes can be introduced as a new class of therapeutic candidates. Metal complexes can be considered as one of the main categories of artificial metalloscissors, which can prompt nucleic acid strand scission. Accordingly, biologists, inorganic chemists, and medicinal inorganic chemists worldwide have been designing, synthesizing and evaluating the biological properties of metal complexes as artificial metalloscissors. In this review, we try to highlight the recent studies conducted on the nuclease-like metalloscissors and their potential therapeutic applications. Under the light of the concurrent Covid-19 pandemic, the human need for new therapeutics was highlighted much more than ever before. The nuclease-like metalloscissors with the potential of RNA cleavage of invading viral pathogens hence deserve prime attention.

Antiproliferative and antibacterial properties of biocompatible copper(II) complexes bearing chelating N,N-heterocycle ligands and potential mechanisms of action

In an attempt to propose new applications for the biomedical field, complexes with mixed ligands {[Cu(bpy)₂(μ₂OClO₃)]ClO₄}n (1) and [Cu(phen)₂(OH₂)](ClO₄)₂ (2) (bpy: 2,2'-biyridine; phen and 1,10-phenantroline) were evaluated for their antibacterial and cytotoxicicity features and for the elucidation of some of the mechanisms involved. Complex (2) proved to be a very potent antibacterial agent, exhibing MIC and MBEC values 2 to 54 times lower than those obtained for complex (1) against both susceptible or resistant Gram-positive and Gram-negative strains, in planktonic or biofilm growth state. In exchange, complex (1) exhibited selective cytotoxicity against melanoma tumor cells (B16), proving a promising potential for developing novel anticancer drugs. The possible mechanisms of both antimicrobial and antitumor activity of the copper(II) complexes is their DNA intercalative ability coupled with ROS generation. The obtained results recommend the two complexes for further development as multipurpose copper-containing drugs.

Synthesis, structure, and DNA binding/cleavage of two novel binuclear Co(II) complexes

In this study, two novel binuclear Co(II) complexes, [Co₄(L₁)₂(CH₃CH₂O)₄·5.5H₂O (1) and [Co₂(L₂)₂(CH₃COO)(H₂O)]·2CH₃OH·3H₂O (2)], with the ligands H₃L₁ and H₂L₂ were synthesized and structurally characterized using single crystal X-ray diffraction. The crystal structures of complex 1 and 2 belong to a monoclinic system with space group of P2(1)/n and triclinic system with space group of P-1, respectively. Their interaction with CT-DNA was investigated using electron absorption and fluorescent spectroscopy. The apparent binding constants (K_app) of two complexes (1 and 2) were determined to be 5.34 × 10⁵ and 5.82 × 10⁵, respectively, and both exhibited a moderate intensity of insertion with 2 > 1. Fluorescence quenching studies indicated that the fluorescence quenching mechanism of complex 1 is dynamic quenching and that of complex 2 is a static quenching mechanism. The chemical nuclease activity of the complexes was studied using agarose gel electrophoresis. The results suggest that when H₂O₂ is added, complexes 1 and 2 exhibit chemical nuclease activity. The cleavage mechanisms between the complexes and plasmid DNA are the likely oxidative cleavage process of hydroxyl radical (OH) and singlet oxygen (¹O₂) as active species.