Synthesis of Aryl-1,2,4,5-tetrazinane-3-thiones, in vitro DNA binding studies, nuclease activity and its antimicrobial activity

Design and synthesis of novel 1,2,3,4-tetrazines as new anti-leukemia cancer agents

A series of novel 1,2,3,4-tetrazines were designed and synthesized. 1 H-NMR spectroscopy, 13 C NMR spectroscopy, and HRMS were used to determine the structures of this novel compounds. Computational approaches suggested that DHFR is a putative target for the newly synthesized 11 compounds. Extensive molecular dynamics simulations followed by molecular docking simulations were employed to evaluate DHFR as a potential target protein. The anticancer activities of the compounds were evaluated against five different types of leukemia cell lines (Jurkat, Nalm-6, Reh, K562, and Molt-4) and one non-leukemic cell line (Hek293T) by MTT test in vitro and imatinib was used as a control drug. Among these compounds, 3a exhibited the best activity against all the leukemic cell lines, except Reh cell line. For Nalm-6, K562, Jurkat, and Molt-4 cell lines, IC50 values were found to be 15.98, 19.12, 23.15, and 25.80 μM, respectively. Our work focuses on the synthesis of original and novel 1,2,3,4-tetrazine derivatives while contributing to the ongoing effort to discover more potent new antileukemia agents.

Synthesis, characterization, computational studies and in vitro antiparasitic activity of novel flavanoidal-1,2,4,5-tetrazinane-6'-thione

Keeping in view the growing resistance of conventional antiparasitic drugs, this study aimed to synthesize a series of six noble flavanoidal tetrazinane-6'-thione derivatives by employing a facile one pot reaction pathway. Structural characterizations of synthesized compounds were performed by using IR, 1HNMR, 13CNMR and LC-MS spectra. Molecular docking study showed that one of the newly synthesized compounds strongly bind with the amino residues of BSA with two hydrogen bonding interactions. Physiological properties, pharmacokinetic properties (ADME) and toxicity of all synthesized compounds was carried out using Molinspiration and pkCSM softwares. DFT calculations were performed for all synthesized compounds using B3LYP method to obtain various molecular properties. Using a previously established model for parasitic infections, Clinostomum complanatum we showed that the newly synthesized compounds have a very potent parasitic activity. To elucidate the possible mechanisms, we tested the exposed parasites and observed a perturbation in lipid peroxidation and the antioxidant enzyme superoxide dismutase. Implications of this are discussed in the light of development of these molecules as antiparasitic drugs. HIGHLIGHTSSix noble flavanoidal-1,2,4,5-tetrazinane-6'-thiones (7-12) were synthesized using flavanone derivatives and thiocarbohydrazide in acetic acid as a reagent in ethanol employing one-pot synthesis.Structural characterization of synthesized compounds was done using IR, 1HNMR, 13CNMR and LC-MS spectra.Physicochemical analysis determined that all synthesized compounds are efficiently absorbed and have good permeability.In silico ADME and Toxic properties were determined for all synthesized compounds.In vitro antiparasitic activity was performed for all synthesized compounds against Clinostomum complanatum.Molecular Docking studies demonstrated the binding interaction with BSA enzyme through hydrogen bonding.Density functional theory (DFT) have been performed to estimate the various molecular properties of the synthesized compounds.Communicated by Ramaswamy H. Sarma.

DNA Binding and Cleavage, Stopped-Flow Kinetic, Mechanistic, and Molecular Docking Studies of Cationic Ruthenium(II) Nitrosyl Complexes Containing “NS4” Core

This work aimed to evaluate in vitro DNA binding mechanistically of cationic nitrosyl ruthenium complex [RuNOTSP]+ and its ligand (TSPH2) in detail, correlate the findings with cleavage activity, and draw conclusions about the impact of the metal center. Theoretical studies were performed for [RuNOTSP]+, TSPH2, and its anion TSP−2 using DFT/B3LYP theory to calculate optimized energy, binding energy, and chemical reactivity. Since nearly all medications function by attaching to a particular protein or DNA, the in vitro calf thymus DNA (ctDNA) binding studies of [RuNOTSP]+ and TSPH2 with ctDNA were examined mechanistically using a variety of biophysical techniques. Fluorescence experiments showed that both compounds effectively bind to ctDNA through intercalative/electrostatic interactions via the DNA helix’s phosphate backbone. The intrinsic binding constants (Kb), (2.4 ± 0.2) × 105 M−1 ([RuNOTSP]+) and (1.9 ± 0.3) × 105 M−1 (TSPH2), as well as the enhancement dynamic constants (KD), (3.3 ± 0.3) × 104 M−1 ([RuNOTSP]+) and (2.6 ± 0.2) × 104 M−1 (TSPH2), reveal that [RuNOTSP]+ has a greater binding propensity for DNA compared to TSPH2. Stopped-flow investigations showed that both [RuNOTSP]+ and TSPH2 bind through two reversible steps: a fast second-order binding, followed by a slow first-order isomerization reaction via a static quenching mechanism. For the first and second steps of [RuNOTSP]+ and TSPH2, the detailed binding parameters were established. The total binding constants for [RuNOTSP]+ (Ka = 43.7 M−1, Kd = 2.3 × 10−2 M−1, ΔG0 = −36.6 kJ mol−1) and TSPH2 (Ka = 15.1 M−1, Kd = 66 × 10−2 M, ΔG0 = −19 kJ mol−1) revealed that the relative reactivity is approximately ([RuNOTSP]+)/(TSPH2) = 3/1. The significantly negative ΔG0 values are consistent with a spontaneous binding reaction to both [RuNOTSP]+ and TSPH2, with the former being very favorable. The findings showed that the Ru(II) center had an effect on the reaction rate but not on the mechanism and that the cationic [RuNOTSP]+ was a more highly effective DNA binder than the ligand TSPH2 via strong electrostatic interaction with the phosphate end of DNA. Because of its higher DNA binding affinity, cationic [RuNOTSP]+ demonstrated higher cleavage efficiency towards the minor groove of pBR322 DNA via the hydrolytic pathway than TSPH2, revealing the synergy effect of TSPH2 in the form of the complex. Furthermore, the mode of interaction of both compounds with ctDNA has also been supported by molecular docking.

Evaluation of (ɳ6-p-cymene) ruthenium diclofenac complex as anticancer chemotherapeutic agent: interaction with biomolecules, cytotoxicity assays

The designing of metal-based anticancer therapeutic agents can be optimized in a better and rapid way if the ligands utilized have standalone properties. Therefore, even when the organometallic/coordination complex (i.e., metallodrug) gets dissociated in extreme conditions, the ligand can endorse its biological properties. Herein, we have synthesized and characterized ɳ⁶-p-cymene ruthenium diclofenac complex. Furthermore, the ruthenium complex interactions with human serum albumin (HSA) and ct-DNA have been studied using various spectroscopic studies viz., UV, fluorescence, and circular dichroism and exhibited a significant binding propensity. Furthermore, in vitro cytotoxicity assays were carried out against human breast cancer "MCF-7" cell line. The ɳ⁶-p-cymene ruthenium diclofenac complex registered significant cytotoxicity with an IC₅₀ value of ∼25.0 µM which is comparable to the standard drugs. The ɳ⁶-p-cymene ruthenium diclofenac complex was able to decrease the MCF-7 cell proliferation and induced significant levels of apoptosis with relatively low toxicity.

ZGDHu-1 for cancer therapy

N,N'-di-(m-methylphenyl)-3,6-dimethyl-1,4-dihydro-1,2,4,5-tetrazine-1,4-dicarboamide (ZGDHu-1) is a novel tetrazine derivative that was initially designed and produced by Professor W.X. Hu, and which has been reported by our group to exhibit antitumor activity. Accumulating evidence suggests that the anticancer mechanisms of ZGDHu-1 may be involved indifferent biological activities, particularly in acute myeloid leukemia (AML) cells. At a high concentration, ZGDHu-1 has been demonstrated to inhibit the proliferation of the leukemia cells by arresting the cell cycle at the G₂/M phase, and by inducing cell apoptosis via inducing the accumulation of reactive oxygen species, the translocation of phosphatidylserine across the plasma membrane and the loss of mitochondrial membrane potential. Furthermore, at a low concentration, it was demonstrated to induce the differentiation and degrade the AML1-eight-twenty-one fusion protein in AML cells. Finally, results from a previous study indicate that ZGDHu-1 is a potential proteasome inhibitor. Overall, our preliminary research suggests that ZGDHu-1 may be a promising anticancer drug; however, further research is warranted to identify the exact drug target and potential clinical application in leukemia cells or solid tumors. In the present review, the application of ZGDHu-1 in cancer research, in addition to the specific underlying targets of ZGDHu-1, are discussed.

Synthesis, antitumor evaluation and 3D-QSAR studies of [1,2,4]triazolo[4,3-b][1,2,4,5]tetrazine derivatives

A series of [1,2,4]triazolo[4,3-b][1,2,4,5]tetrazine derivatives have been synthesized and their structures were confirmed by single-crystal X-ray diffraction. Compared to some reported structures of 1,6-dihydro-1,2,4,5-tetrazine, these compounds can't be considered as having homoaromaticity. Their antiproliferative activities were evaluated against MCF-7, Bewo and HL-60 cells in vitro. Two compounds were highly effective against MCF-7, Bewo and HL-60 cells with IC50 values in 0.63-13.12μM. Three-dimensional quantitative structure-activity relationship (3D-QSAR) studies of comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were carried out on 51 [1,2,4]triazolo[4,3-b][1,2,4,5]tetrazine derivatives with antiproliferative activity against MCF-7 cell. Models with good predictive abilities were generated with the cross validated q(2) values for CoMFA and CoMSIA being 0.716 and 0.723, respectively. Conventional r(2) values were 0.985 and 0.976, respectively. The results provide the tool for guiding the design and synthesis of novel and more potent tetrazine derivatives.

Design, synthesis and mode of action of some benzothiazole derivatives bearing an amide moiety as antibacterial agents

Schematic outline of the most potent compound, benzothiazole bearing amide moiety A07, showing antibacterial activity and its mode of action.