A new synthetic pathway was reported to obtain N6 donor ligand 2,9-bis-(2′,5′-diazahexanyl)-1,10-phenanthroline (L1) and its coordination compounds of essential divalent metal ions Mn, Fe, Co, Ni, Cu and Zn. Complete characterization of all compounds was done with the conventional techniques. Crystal structures of [NiL1](PF₆)₂ and [ZnL1](PF₆)₂·H₂O were also reported. Electrochemical studies have shown an active participation of the aromatic moiety of the ligand in redox reactions. The in vitro tests of the cytotoxic activity against human tumour cell lines HeLa (cervix) and CHP-212 (neuroblastoma) showed that all coordination compounds that involve redox active metal ions exhibit noteworthy antiproliferative activity, superior in all cases to cisplatin. [CuL1]²⁺ showed the lower IC₅₀ value in the HeLa cell line with 1.84 μM, meanwhile, [CoL1]²⁺ showed the lower value in neuroblastoma CHP-212 with IC₅₀ = 45.28 μM. None of these compounds were active against the SK-N-SH neuroblastoma cell line. In Entamoeba histolytica cultures, remarkable nanomolar IC₅₀ values were found for [NiL1]²⁺ and [MnL1]²⁺ with 60 nM and 80 nM respectively, improving the antiproliferative activity more than 1000 times compared with the first choice drug for clinical treatments of human amoebiasis, metronidazole. On the other hand, a free ligand does not show antiproliferative activity either on human tumor cell lines or on Entamoeba histolytica trophozoites, highlighting the role played by metal ions to produce cytotoxicity in tumor cells and protozoa systems.

Computational combined protocols suggest that Casiopeinas can block the active site of M^proSARS-CoV-2 by binding to its main amino acids.

Objectives The present study aims to evaluate the antimicrobial property of Casiopeinas® copper- and ruthenium-based compounds against Aggregatibacter actinomycetemcomitans serotype b (ATCC® 43,718™), as well as the cytotoxicity on an osteoblasts cell line of both compounds. Material and methods The antibacterial effect of the copper-based compounds (CasII-gly, CasIII-ia) and the ruthenium-based compound (RuN-6) at four different concentrations was evaluated as the inhibition ratio of the bacterial growth after 48 h under anaerobic conditions, and the cell viability was measured through resazurin assay. Results The copper- and ruthenium-based compounds used for this assay were (CasII-gly, CasIII-ia, and RuN-6), showing inhibitory activity between 39 and 62% compared to the antibiotic employed as control 66%. Cell viability was established between 61 and 96%. Conclusions Casiopeinas® and ruthenium showed dose and time dependent, inhibitory activity on A. actinomycetemcomitans, and low toxicity on cells (osteoblast) underexposure. The compound CasII-gly showed the best antimicrobial effect, and it could be considered a possible antimicrobial agent in periodontal therapy.

In this research, we investigate the interaction between the redox mediator ferrocene carboxylic acid (Fc-COOH) and glucose oxidase (GOD) in order to determine the thermodynamics parameters Kint, ΔGint, ΔHint, and ΔSint using simple UV–visible experiments at different temperatures. Positive values of ΔHint, ΔSint, together with a negative value of ΔGint indicate an entropy-driven hydrophobic interaction typical of spontaneous association processes. The homogeneous electron transfer rate constants between the oxidized organometallic mediator and the reduced enzyme (ks), along with their activation parameters (ΔGET≠, ΔHET≠ and ΔSET≠), were calculated using data obtained from foot of the wave analysis (FOWA) of cyclic voltammetry experiments performed at variable temperature. According to transition state theory, the obtained parameters indicate a low activation enthalpy that reflects minimal energetic requirements for electron transfer, while the large negative activation entropy suggests the formation of an ordered transition state. The positive activation free energy falls within the expected range for biological electron transfer processes. Variable temperature cyclic voltammetry experiments of ferrocene carboxylic acid (Fc-COOH) were also performed. The obtained ΔG°, ΔH°, and ΔS° parameters indicate strong stabilization of the redox pair, consistent with a small difference in solvation energy. Circular dichroism, UV–vis spectroscopy, and combined CD and UV–Vis Spectroelectrochemistry measurements performed during redox mediation demonstrate that no significant structural alterations occur in either the enzyme or the redox mediator before or during the electron transfer processes.

This work investigates the coordination compound [Zn(2,2-bpy)₃](BF₄)₂ as a catalyst for the molecular reduction of CO₂. The synthesis and characterization of the complex are reported, along with electrochemical studies conducted both in the presence and absence of CO₂. In the absence of CO₂, reduction of the 2,2′-bipyridine ligands was observed (Epa(I) = −1.84 V vs. Fc/Fc⁺ and Epa(II) = −2.18 V vs. Fc/Fc⁺). In contrast, under a CO₂ atmosphere, catalytic molecular activity toward CO₂ reduction was detected (Epk(I) = −1.90 V vs. Fc/Fc⁺ and Epk(II) = −2.18 V vs. Fc/Fc⁺). Foot of the wave analysis (FOWA) was employed to determine the catalytic rate constant (k = 1.352 × 10³ M⁻¹ s⁻¹) for CO₂ reduction. Spectroelectrochemical experiments were also carried out in both the presence and absence of CO₂. Density functional theory (DFT) calculations were conducted to understand the interaction of the complex with CO₂. Bulk electrolysis and FTIR analysis suggest that oxalate is the product of the CO₂ reduction.

In this work, the synthesis and characterization of fourteen Casiopeinas® are presented, whose general formulae is [Cu(N-N)(L-L)]NO3, where N-N are 2,2´-bipirydine and 1,10-phenanthroline and some of its methylated derivatives, L-L represent the dipeptides L-Tyrosil-Glycinate or Glycil-L-Tyrosinate. Spectroscopic characterization and DFT studies determine the square planar geometry for the coordination compounds, as well as the influence of the dipeptide on the molecular arrangement of ternary copper(II) compounds. In addition, a molecular docking study was carried out against transcendental proteins of the SARS-CoV-2 virus such as main protease (Mpro) and the RBD Spike-ACE2 complex. Docking studies indicate that all compounds can produce stable adducts with Mpro, obtaining ΔGU values (-9.57 to -6.62 Kcal/mol) similar and superior to those presented by the reference inhibitors [boceprevir (-8.44 Kcal/mol) and remdesivir (-6.62 kcal/mol)], while for the RBD Spike-ACE2 complex obtaining ΔGU values of five (-6.69 to -4.61 in C-terminal region) and three (-8.27 to -6.34 in central region) orders of magnitude higher than those presented by the controls (Boceprevir: ΔGU=-1.98 in C-terminal, ΔGU=-4.97 in central region, Remdesivir: ΔGU=Non interactions in C-terminal, ΔGU=-3.37 in central region). π-alkyl interactions, π -cation, π -stacking, as well as hydrogen bonds and salt bridge bonds occur between the proteins and Casiopeinas®. In Mpro, interactions occur in aminoacids that are part of the enzymes catalytic site. Casiopeinas® interact at the interface of the RDB Spike-ACE2 complex in both, C-terminal and central regions. The obtained results position Casiopeinas® as potential candidates protein inhibitors of the virus that causes COVID-19. Resumen. En este trabajo, se presenta la síntesis y caracterización de 14 Casiopeinas®, cuya fórmula general es [Cu(N-N)(L-L)]NO3, donde N-N son 2,2´-bipiridina y derivados metilados o 1,10-fenantrolina y análogos con grupos metilo, L-L representan a los dipéptidos L-Tirosil-Glicinato o Glicil-L-Tirosinato. Mediante estudios espectroscópicos y de DFT determinan la geometría cuadrada de los compuestos sintetizados, así como la influencia del dipéptido en el arreglo molecular de los compuestos ternarios de cobre(II). Complementariamente, se realizó un estudio de docking molecular ante proteínas trascendentales del virus SARS-CoV-2 como lo son la proteasa principal (MPro o nsps-3) y el complejo RBD Spike-ACE2. Estudios de docking molecular con la MPro se obtuvieron valores de ΔGU (-9.57 a -6.629) kcal/mol, valores que son similares y superiores a los presentados por los inhibidores de referencia [boceprevir (-8.44 kcal/mol) y remdesivir (-6.62 kcal/mol)], mientras que para el complejo RBD Spike-ACE2 se obtuvieron valores de ΔGU de cinco (-6.69 to -4.61 en región C-terminal) y tres (-8.27 to -6.34 en región central) órdenes de magnitud superiores respectivamente a los presentados por los inhibidores de referencia (Boceprevir: ΔGU=-1.98 en C-terminal, ΔGU=-4.97 en region central, Remdesivir: ΔGU=Sin interacciones en C-terminal, ΔGU=-3.37 en region central). Interacciones π-alquilo, π-catión, apilamiento π, así como enlaces puentes de hidrogeno y puentes de sal se producen entre las proteínas y Casiopeinas® estudiadas. En Mpro, las interacciones ocurren en aminoácidos que forman parte del sitio catalítico de la enzima. Las Casiopeinas® interactúan en la interfase del complejo RBD Spike-ACE2 tanto en la región C-terminal como en la región central. Los resultados obtenidos, posicionan a las Casiopeinas® como potenciales candidatos a inhibidores proteicos del virus causante de la COVID-19.