Synthesis and Antitumor Activity Evaluation of Cyclometalated 2H‐ Indazole Ruthenium(II) and Iridium(III) Complexes

Anti-cancer property and DNA binding interaction of first row transition metal complexes: A decade update

Metal ions carry out a wide variety of functions, including acid-base/redox catalysis, structural functions, signaling, and electron transport. Understanding the interactions of transition metal complexes with biomacromolecules is essential for biology, medicinal chemistry, and the production of synthetic metalloenzymes. After the coincidental discovery of cisplatin, importance of the metal complexes in biochemistry became a top priority for inquiry. In this review, a decade update on various synthetic strategies to first row transition metal complex and their interaction with DNA through non-covalent binding are explored. Moreover, this effort provides an excellent analysis on the efficacy of theoretical and practical approaches to the systematic generation of new non-platinum based metallodrugs for anti-cancer therapeutics.

Mitochondria-targeted cyclometalated iridium (III) complexes: Dual induction of A549 cells apoptosis and autophagy

In this study, we synthesized 4 cyclometalated iridium complexes using N-(1,10-phenanthrolin-5-yl)picolinamide (PPA) as the main ligand, denoted as [Ir(ppy)2PPA]PF6 (ppy = 2-phenylpyridine, Ir1), [Ir(bzq)2PPA]PF6 (bzq = benzo[h]quinoline, Ir2), [Ir(dfppy)2PPA]PF6 (dfppy = 2-(3,5-difluorophenyl)pyridine, Ir3), and [Ir(thpy)2PPA]PF6 (thpy = 2-(thiophene-2-yl)pyridine, Ir4). Compared to cisplatin and oxaliplatin, all four complexes exhibited significant anti-tumor activity. Among them, Ir2 demonstrated higher cytotoxicity against A549 cells, with an IC50 value of 1.6 ± 0.2 μM. The experimental results indicated that Ir2 primarily localized in the mitochondria, inducing a large amount of reactive oxygen species (ROS) generation, that decreased in mitochondrial membrane potential (MMP), reduced ATP production, and further impaired mitochondrial function, leading to cytochrome c release. Additionally, Ir2 caused cell cycle arrest at the S phase and induced apoptosis through the AKT-mediated signaling pathway. Further investigations revealed that Ir2 could simultaneously induce both apoptosis and autophagy in A549 cells, with the latter acting as a non-protective mechanism that promoted cell death. More importantly, Ir2 exhibited low toxicity to both normal LO2 cells in vitro and zebrafish embryos in vivo. Consequently, these newly developed Ir(III) complexes show great potential in the development of novel and low-toxicity anticancer agents.

Photodynamic antitumor activity of Gallium(III) and Phosphorus(V) complexes of trimethoxyl A2B triaryl corrole

Two new trimethoxyl A₂B triaryl corroles 10-(2,4,6-trimethoxyphenyl)-5,15-bis(pentafluorophenyl)- corrole (1) and 10-(3,4,5-trimethoxyphenyl)-5,15-bis(pentafluorophenyl)-corrole (2) and their gallium(III) and phosphorus(V) (1-Ga, 1-P, 2-Ga and 2-P) complexes had been prepared and well characterized by UV-vis, NMR and HR-MS. Among all compounds, 2-Ga, 1-P and 2-P showed excellent in vivo photodynamic activity against the MDA-MB-231, A549, Hela and HepG2 cell lines upon light irradiation at 625 nm. And 2-P even exhibited higher phototoxicity than the clinical photosensitizer temoporfin. Also, 2-P exhibited the highest singlet oxygen quantum yield and photostability. The preliminary investigation revealed that 2-P could be rapidly absorbed by tumor cells and mainly located in the cytoplasm. After photodynamic therapy (PDT) treatment with 2-P, mitochondrial membrane potential destruction, intracellular ROS level increasing and nuclear fragmentation of cancer cells could be observed. Cell cycle analysis demonstrated that the 2-P PDT may cause tumor cell arrest at sub-G1 stage and induce early and late apoptosis of cells. These results suggest that 2-P is a promising candidate as a photosensitizer for photodynamic therapy.

In-silico molecular modelling, MM/GBSA binding free energy and molecular dynamics simulation study of novel pyrido fused imidazo[4,5-c]quinolines as potential anti-tumor agents

With an alarming increase in the number of cancer patients and a variety of tumors, it is high time for intensive investigation on more efficient and potent anti-tumor agents. Though numerous agents have enriched the literature, still there exist challenges, with the availability of different targets and possible cross-reactivity. Herein we have chosen the phosphoinositide 3-kinase (PI3K) as the target of interest and investigated the potential of pyrido fused imidazo[4,5-c]quinoline derivatives to bind strongly to the active site, thereby inhibiting the progression of various types of tumors. The AutoDock, Glide and the Prime-MM/GBSA analysis are used to execute the molecular docking investigation and validation for the designed compounds. The anti-tumor property evaluations were carried out by using PASS algorithm. Based on the GLIDE score, the binding affinity of the designed molecules towards the target PI3K was evaluated. The energetics associated with static interactions revealed 1j as the most potential candidate and the dynamic investigations including RMSD, RMSF, Rg, SASA and hydrogen bonding also supported the same through relative stabilization induced through ligand interactions. Subsequently, the binding free energy of the Wortmannin and 1j complex calculated using MM-PBSA analysis. Further evaluations with PASS prediction algorithm also supported the above results. The studies reveal that there is evidence for considering appropriate pyrido fused imidazo[4,5-c]quinoline compounds as potential anti-tumor agents.

2-Aminopyridine - an unsung hero in drug discovery

2-Aminopyridine is a simple, low molecular weight and perfectly functionalised moiety known for the synthesis of diverse biological molecules. Many pharmaceutical companies across the globe aim to synthesise low-molecular weight molecules for use as pharmacophores against various biological targets. 2-Aminopyridine can serve as a perfect locomotive in the synthesis and pulling of such molecules towards respective pharmacological goals. The major advantage of this moiety is its simple design, which can be used to produce single products with minimum side reactions. Moreover, the exact weight of synthesised compounds is low, which enables facile identification of toxicity-causing metabolites in drug discovery programmes. This manuscript is a quick review of such pharmacophores derived from 2-aminopyridine.

Chemical Characterization and Biological Evaluation of New Cobalt(II) Complexes with Bioactive Ligands, 2-Picolinehydroxamic Acid and Reduced Schiff Base N-(2-Hydroxybenzyl)alanine, in Terms of DNA Binding and Antimicrobial Activity

Five new heteroligand cobalt(II) complexes with 2-picolinehydroxamic acid and reduced Schiff base, N-(2-hydroxybenzyl)alanine, were formed in an aqueous solution over a wide pH range. The coordination properties of ligands towards the metal ion were determined using a pH-metric method, and then the speciation model was confirmed by UV–Vis studies. A stacking interaction between the Schiff base phenol ring and the 2-picolinehydroxamic acid pyridine ring was found to improve the stability of the heteroligand species, indicating more effective coordination in mixed-ligand complexes than in their respective binary systems. The antimicrobial properties of heteroligand complexes were determined against Gram-negative and Gram-positive bacteria, as well as fungal strains. The formulation demonstrated the highest bacteriostatic and bactericidal activity (3.65 mM) against two strains of Gram-negative Helicobacter pylori bacteria and towards Candida albicans and Candida glabrata; this is important due to the potential co-existence of these microorganisms in the gastric milieu and their role in the development of gastritis. The binary complexes in the cobalt(II)—2-picolinehydroxamic acid system and 2-picolinehydroxamic acid were not cytotoxic against L929 mouse fibroblasts, neither freshly prepared solutions or after two weeks’ storage. By comparison, the heteroligand complexes within the range 0.91–3.65 mM diminished the metabolic activity of L929 cells, which was correlated with increased damage to cell nuclei. The concentration of the heteroligand species increased over time; therefore, the complexes stored for two weeks exhibited stronger anticellular toxicity than the freshly prepared samples. The complexes formed in an aqueous solution under physiological pH effectively bound to calf thymus DNA in an intercalative manner. This DNA-binding ability may underpin the antimicrobial/antifungal activity of the heteroligand complexes and their ability to downregulate the growth of eukaryotic cells.

An overview of metal-free synthetic routes to isoxazoles: the privileged scaffold

In the field of drug discovery, isoxazole is a five-membered heterocyclic moiety commonly found in many commercially available drugs. In view of their enormous significance, it is always imperative to unleash new eco-friendly synthetic strategies. Among various novel synthetic techniques in use for isoxazole synthesis, most synthetic methods employ Cu(i) or Ru(ii) as catalysts for (3 + 2) cycloaddition reaction. The particular disadvantages associated with metal-catalyzed reactions are high costs, low abundance, toxicity, a significant generation of waste, and difficulty to separate from the reaction mixtures. In view of these drawbacks, it is always imperative to develop alternate metal-free synthetic routes. This review article highlights a comprehensive overview on the potential application of metal-free synthetic routes for the synthesis of isoxazoles with significant biological interests.

An expeditious microwave assisted one-pot sequential route to pyrido fused imidazo[4,5-c] quinolines in green media

A novel one-pot sequential route for the synthesis of pyrido[2′,1′:2,3]imidazo[4,5-c]quinolines via microwave-assisted sequential reaction of 2-aminopyridines, 2-bromophenacyl bromides, and aldehydes has been developed in green media.

Diversity-Oriented Synthesis of Thiazolidine-2-imines via Microwave-Assisted One-Pot, Telescopic Approach and Its Interaction with Biomacromolecules

In this work, a one-pot, telescopic approach is described for the combinatorial library of thiazolidine-2-imines. The synthetic manipulation proceeds smoothly via the reaction of 2-aminopyridine/pyrazine/pyrimidine with substituted isothiocyanates followed by base catalyzed ring closure with 1,2-dibromoethane to obtain thiazolidine-2-imines with broad substrate scope and high functional group tolerance. The synthetic strategy merges well with the thiourea formation followed by base catalyzed ring closure reaction for the thiazolidine-2-imine synthesis in a more modular and straightforward approach. The synthetic procedure reported herein represents a cleaner route toward thiazolidine-2-imines as compared to traditional methodologies. Moreover, the biological significance of combinatorially synthesized thiazolidin-2-imines has been investigated for their use as possible inhibitors for acetyl cholinesterase through molecular docking studies.