Anthra[1,2-d][1,2,3]triazine-4,7,12(3H)-triones as a New Class of Antistaphylococcal Agents: Synthesis and Biological Evaluation

Applications of Boron Cluster Supramolecular Frameworks as Metal-Free Chemodynamic Therapy Agents for Melanoma

Chemodynamic therapy (CDT) is a highly targeted approach to treat cancer since it converts hydrogen peroxide into harmful hydroxyl radicals (OH·) through Fenton or Fenton-like reactions. However, the systemic toxicity of metal-based CDT agents has limited their clinical applications. Herein, a metal-free CDT agent: 2,4,6-tri(4-pyridyl)-1,3,5-triazine (TPT)/ [closo-B12 H12 ]2- (TPT@ B12 H12 ) is reported. Compared to the traditional metal-based CDT agents, TPT@B12 H12 is free of metal avoiding cumulative toxicity during long-term therapy. Density functional theory (DFT) calculation revealed that TPT@B12 H12 decreased the activation barrier more than 3.5 times being a more effective catalyst than the Fe2+ ion (the Fenton reaction), which decreases the barrier about twice. Mechanismly, the theory calculation indicated that both [B12 H12 ]-· and [TPT-H]2+ have the capacity to decompose hydrogen into 1 O2 , OH·, and O2 -· . With electron paramagnetic resonance and fluorescent probes, it is confirmed that TPT@B12 H12 increases the levels of 1 O2 , OH·, and O2 -· . More importantly, TPT@B12 H12 effectively suppress the melanoma growth both in vitro and in vivo through 1 O2 , OH·, and O2 -· generation. This study specifically highlights the great clinical translational potential of TPT@B12 H12 as a CDT reagent.

A Promising 1,3,5-Triazine-Based Anion Exchanger for Perrhenate Binding: Crystal Structures of Its Chloride, Nitrate and Perrhenate Salts

The reaction of pyridine with cyanuric chloride was studied under microwave activation as well as in the presence of silver nitrate. The product of hydrolysis containing two pyridinium rings and chloride anion was isolated. The structures of these anion exchanger salts with chloride, nitrate and perrhenate anions are discussed.

A Ring Opening–Annulation Reaction of Anthra[1,2-d][1,2,3]triazine-4,7,12(3H)-trione in the Presence of Pyridines as an Efficient Approach to the Construction of Naphtho[2,3-H]pyrido(quinolino)[2,1-b]quinazoline System

The [1,2,3]triazin-4(3H)-one ring is a synthetically important molecular platform for a variety of chemical transformations. Despite this, currently, there has been little research on the reaction of the thermal opening of the [1,2,3]triazin-4(3H)-one nucleus. In this work, we describe the synthetic potential of anthra[1,2-d][1,2,3]triazine-4,7,12(3H)-trione in the reaction of the thermal opening of a cycle following the [4+2]-cycloaddition reaction with a number of pyridine derivatives and quinoline. It is shown that this method is effective for the synthesis of the 6H-naphtho[2,3-H]pyrido(quinolino)[2,1-b]quinazoline-6,9,14-trione system. We also investigate the influence of the position of substituents in the structure of pyridine on the formation characteristics of the target products.

Functionalized Triazines and Tetrazines: Synthesis and Applications

The molecules possessing triazine and tetrazine moieties belong to a special class of heterocyclic compounds. Both triazines and tetrazines are building blocks and have provided a new dimension to the design of biologically important organic molecules. Several of their derivatives with fine-tuned electronic properties have been identified as multifunctional, adaptable, switchable, remarkably antifungal, anticancer, antiviral, antitumor, cardiotonic, anti-HIV, analgesic, anti-protozoal, etc. The objective of this review is to comprehensively describe the recent developments in synthesis, coordination properties, and various applications of triazine and tetrazine molecules. The rich literature demonstrates various synthetic routes for a variety of triazines and tetrazines through microwave-assisted, solid-phase, metal-based, [4+2] cycloaddition, and multicomponent one-pot reactions. Synthetic approaches contain linear, angular, and fused triazine and tetrazine heterocycles through a combinatorial method. Notably, the triazines and tetrazines undergo a variety of organic transformations, including electrophilic addition, coupling, nucleophilic displacement, and intramolecular cyclization. The mechanistic aspects of these heterocycles are discussed in a detailed way. The bioorthogonal application of these polyazines with various strained alkenes and alkynes provides a new prospect for investigations in chemical biology. This review systematically encapsulates the recent developments and challenges in the synthesis and possible potential applications of various triazine and tetrazine systems.

In Vitro Anticancer Screening and Preliminary Mechanistic Study of A-Ring Substituted Anthraquinone Derivatives

Anthraquinone derivatives exhibit various biological activities, e.g., antifungal, antibacterial and in vitro antiviral activities. They are naturally produced in many fungal and plant families such as Rhamnaceae or Fabaceae. Furthermore, they were found to have anticancer activity, exemplified by mitoxantrone and pixantrone, and many are well known redox-active compounds. In this study, various nature inspired synthetic anthraquinone derivatives were tested against colon, prostate, liver and cervical cancer cell lines. Most of the compounds exhibit anticancer effects against all cell lines, therefore the compounds were further studied to determine their IC₅₀-values. Of these compounds, 1,4-bis(benzyloxy)-2,3-bis(hydroxymethyl)anthracene-9,10-dione (4) exhibited the highest cytotoxicity against PC3 cells and was chosen for a deeper look into its mechanism of action. Based on flow cytometry, the compound was proven to induce apoptosis through the activation of caspases and to demolish the ROS/RNS and NO equilibrium in the PC3 cell line. It trapped cells in the G2/M phase. Western blotting was performed for several proteins related to the effects observed. Compound 4 enhanced the production of PARP and caspase-3. Moreover, it activated the conversion of LC3A/B-I to LC3A/B-II showing that also autophagy plays a role in its mechanism of action, and it caused the phosphorylation of p70 s6 kinase.

Effect of Ethanol Extracts of Propolis (EEPs) against Staphylococcal Biofilm-Microscopic Studies

Staphylococci growing in the form of biofilm exhibit high resistance to a plethora of antibiotics. The aim of the study was to assess the influence of ethanolic extract of propolis (EEPs) on S. epidermidis ATCC 35984 biofilm using fluorescent microscopy. Propidium iodide (PI) and SYTO 9 were used for differentiation of live and dead cells, and calcofluor white was used to stain the extracellular matrix, the self-produced extracellular polymeric substances (EPS). The outcomes of the research confirm the promising potential of EEPs for eradication of staphylococcal biofilm. However, its activity cannot be classified as fully satisfactory, either in terms of the effectiveness of elimination of bacterial cells or disturbing the EPS structure. A two or even four times higher concentration of EEPs compared to MIC (Minimum Inhibitory Concentration) against planktonic cells (128 µg/mL) was necessary for effective (estimated for 90%) elimination of living cells from the biofilm structure. Unfortunately, even at that concentration of EEPs, the extracellular matrix was only partially disturbed and effectively protected the residual population of living cells of S. epidermidis ATCC 35984. In our opinion, a combination of EEPs with agents disrupting components of EPS, e.g., proteases, lysines, or enzymes degrading extracellular DNA or PIA (polysaccharide intercellular adhesin).

The Chemistry of Triazine Isomers: Structures, Reactions, Synthesis and Applications

Triazine is the six-membered heterocyclic ring containing three nitrogens, which replace the carbon-hydrogen unit in the benzene ring. Based on nitrogen position present in the ring system, it is categorized in three isomeric forms, i.e., 1, 2, 3-triazine (vicinal triazine), 1, 2, 4-triazine (asymmetrical triazine or isotriazine) and 1, 3, 5-triazine (symmetrical or s-triazine or cyanidine). Triazines have a weakly basic property. Their isomers have much weaker resonance energy than benzene structure, so nucleophilic substitution reactions are more preferred than electrophilic substitution reactions. Triazine isomers and their derivatives are known to play important roles possessing various activities in medicinal and agricultural fields such as anti-cancer, antiviral, fungicidal, insecticidal, bactericidal, herbicidal, antimalarial and antimicrobial agents.