Some Old and New Redox Reactions of Polynuclear Organometallic Complexes

1995 ◽  
pp. 297-316
Author(s):  
Heinrich Vahrenkamp
Keyword(s):  
Redox Reactions ◽  
Organometallic Complexes

Redox Reactions in Lipid Membranes as a Model for Primordial Energy-Conserving Systems

1997 ◽  
Vol 161 ◽  
pp. 437-442
Author(s):  
Salvatore Di Bernardo ◽  
Romana Fato ◽  
Giorgio Lenaz
Keyword(s):  
Experimental Evidence ◽  
Lipid Membranes ◽  
Energy Supply ◽  
Redox Reactions ◽  
Living Systems ◽  
Asymmetric Distribution ◽  
Conservation Of Energy ◽  
Asymmetrical Distribution ◽  
Energy Conserving ◽  
Living Organisms

AbstractOne of the peculiar aspects of living systems is the production and conservation of energy. This aspect is provided by specialized organelles, such as the mitochondria and chloroplasts, in developed living organisms. In primordial systems lacking specialized enzymatic complexes the energy supply was probably bound to the generation and maintenance of an asymmetric distribution of charged molecules in compartmentalized systems. On the basis of experimental evidence, we suggest that lipophilic quinones were involved in the generation of this asymmetrical distribution of charges through vectorial redox reactions across lipid membranes.

Bio-organometallic Peptide Conjugates: Recent Advances in Their Synthesis and Prospects for Biomedical Application

2020 ◽  
Vol 24 (21) ◽  
pp. 2508-2523
Author(s):  
Johana Gómez ◽  
Diego Sierra ◽  
Constanza Cárdenas ◽  
Fanny Guzmán
Keyword(s):  
Amino Acids ◽  
Biomedical Application ◽  
Structural Diversity ◽  
Biological Properties ◽  
Therapeutic Agents ◽  
Organometallic Complexes ◽  
Chemical Behavior ◽  
Metal Compounds ◽  
Bioorganometallic Chemistry ◽  
Pharmacological Control

One area of organometallic chemistry that has attracted great interest in recent years is the syntheses, characterization and study of organometallic complexes conjugated to biomolecules with different steric and electronic properties as potential therapeutic agents against cancer and malaria, as antibiotics and as radiopharmaceuticals. This minireview focuses on the unique structural diversity that has recently been discovered in α- amino acids and the reactions of metallocene complexes with peptides having different chemical behavior and potential medical applications. Replacing α-amino acids with metallocene fragments is an effective way of selectively influencing the physicochemical, structural, electrochemical and biological properties of the peptides. Consequently, research in the field of bioorganometallic chemistry offers the opportunity to develop bioactive metal compounds as an innovative and promising approach in the search for pharmacological control of different diseases.

Anti-toxicant Properties of Saffron and Relevance to Protection from Toxins and Drugs

2020 ◽  
Vol 16 (3) ◽  
pp. 265-283
Author(s):  
Kyriaki Hatziagapiou ◽  
George I. Lambrou
Keyword(s):  
Redox Reactions ◽  
Case Reports ◽  
Meta Analysis ◽  
Reactive Oxygen ◽  
Crocus Sativus ◽  
Protective Effects ◽  
Nitrogen Species ◽  
Eligibility Criteria ◽  
Crocus Sativus L

Background: Reactive oxygen species and reactive nitrogen species, which are collectively called reactive oxygen nitrogen species, are inevitable by-products of cellular metabolic redox reactions, such as oxidative phosphorylation in the mitochondrial respiratory chain, phagocytosis, reactions of biotransformation of exogenous and endogenous substrata in endoplasmic reticulum, eicosanoid synthesis, and redox reactions in the presence of metal with variable valence. Among medicinal plants there is a growing interest in Crocus sativus L. It is a perennial, stemless herb, belonging to Iridaceae family, cultivated in various countries such as Greece, Italy, Spain, Israel, Morocco, Turkey, Iran, India, China, Egypt and Mexico. Objective: The present study aims to address the anti-toxicant role of Crocus sativus L. in the cases of toxin and drug toxification. Materials and Methods: An electronic literature search was conducted by the two authors from 1993 to August 2017. Original articles and systematic reviews (with or without meta-analysis), as well as case reports were selected. Titles and abstracts of papers were screened by a third reviewer to determine whether they met the eligibility criteria, and full texts of the selected articles were retrieved. Results: The authors focused on literature concerning the role of Crocus Sativus L. as an anti-toxicant agent. Literature review showed that Saffron is a potent anti-toxicant agent with a plethora of applications ranging from anti-oxidant properties, to chemotherapy protective effects. Conclusion: Literature findings represented in current review herald promising results for using Crocus Sativus L. and/or its active constituents as anti-toxicant, chemotherapy-induced protection and toxin protection.

Induction of Apoptosis by Nano‐Synthesized Complexes of H2L and its Cu(II) Complex in Human Hepatocellular Carcinoma Cells

2020 ◽  
Vol 20 ◽  
Author(s):  
Thoria Diab ◽  
Tarek M. Mohamed ◽  
Alaa Hamed ◽  
Mohamed Gaber
Keyword(s):  
Cell Cycle ◽  
Metal Complexes ◽  
Hepg2 Cells ◽  
Therapeutic Potential ◽  
Free Ligand ◽  
Organometallic Complexes ◽  
Phase Cell ◽  
Sod Activity ◽  
Induced Apoptosis

Background: Chemotherapy is currently the most utilized treatment for cancer. Therapeutic potential of metal complexes in cancer therapy has attracted a lot of interest. The mechanisms of action of most organometallic complexes are poorly understood. Objective: This study was designed to explore the mechanisms governing the anti-proliferative effect of the free ligand N1,N6‐bis((2‐hydroxynaphthalin‐1‐yl)methinyl)) adipohydrazone (H2L) and its complexes of Mn(II), Co(II), Ni(II) and Cu(II). Methods: Cells were exposed to H2L or its metal complexes where cell viability determined by MTT assay. Cell cycle was analysed by flow cytometry. In addition, qRT-PCR was used to monitor the expression of Bax and Bcl-2. Moreover, molecular docking was carried out to find the potentiality of Cu(II) complex as an inhibitor of Adenosine Deaminase (ADA). ADA, Superoxide Dismutase (SOD) and reduced Glutathione (GSH) levels were measured in the most affected cancer cell line. Results: The obtained results demonstrated that H2L and its Cu(II) complex exhibited a strong cytotoxic activity compared to other complexes against HepG2 cells (IC50 = 4.14±0.036μM/ml and 3.2±0.02μM/ml), respectively. Both H2L and its Cu(II) complex induced G2/M phase cell cycle arrest in HepG2 cells. Additionally, they induced apoptosis in HepG2 cells via upregulation of Bax and downregulation of Bcl-2. Interestingly, the activity of ADA was decreased by 2.8 fold in HepG2 cells treated with Cu(II) complex compared to untreated cells. An increase of SOD activity and GSH level in HepG2 cells compared to control was observed. Conclusion: The results concluded that Cu(II) complex of H2L induced apoptosis in HepG2 cells. Further studies are needed to confirm its anti-cancer effect in vivo.

Updated understanding of platelets in thrombosis and hemostasis: the roles of integrin PSI domains and their potential as therapeutic targets

2020 ◽  
Vol 20 ◽  
Author(s):  
Daniel Thomas MacKeigan ◽  
Tiffany Ni ◽  
Chuanbin Shen ◽  
Tyler William Stratton ◽  
Wenjing Ma ◽  
...  
Keyword(s):  
Redox Reactions ◽  
Platelet Adhesion ◽  
Adaptive Mechanism ◽  
Dynamic Interactions ◽  
Surface Receptors ◽  
Isomerase Activity ◽  
Pathological Conditions ◽  
Fibrinogen Binding ◽  
Immune Mediated ◽  
Novel Target

: Platelets are small blood cells known primarily for their ability to adhere and aggregate at injured vessels to arrest bleeding. However, when triggered under pathological conditions, the same adaptive mechanism of platelet adhesion and aggregation may cause thrombosis, a primary cause of heart attack and stroke. Over recent decades, research has made considerable progress in uncovering the intricate and dynamic interactions that regulate these processes. Integrins are heterodimeric cell surface receptors expressed on all metazoan cells that facilitate cell adhesion, movement, and signaling, to drive biological and pathological processes such as thrombosis and hemostasis. Recently, our group discovered that the plexinsemaphorin-integrin (PSI) domains of the integrin β subunits exert endogenous thiol isomerase activity derived from their two highly conserved CXXC active site motifs. Given the importance of redox reactions in integrin activation and its location in the knee region, this PSI domain activity may be critically involved in facilitating the interconversions between integrin conformations. Our monoclonal antibodies against the β3 PSI domain inhibited its thiol isomerase activity and proportionally attenuated fibrinogen binding and platelet aggregation. Notably, these antibodies inhibited thrombosis without significantly impairing hemostasis or causing platelet clearance. In this review, we will update mechanisms of thrombosis and hemostasis including platelet versatilities and immune-mediated thrombocytopenia, discuss critical contributions of the newly discovered PSI domain thiol isomerase activity, and its potential as a novel target for anti-thrombotic therapies and beyond.

Kinetics and mechanism of redox reactions of U(III) ions with monochloroacetic and dichloroacetic acids

1979 ◽  
Vol 44 (2) ◽  
pp. 401-405 ◽  
Author(s):  
Ľubica Adamčíková ◽  
Ľudovít Treindl
Keyword(s):  
Redox Reactions ◽  
Reaction Rate ◽  
Activation Parameters ◽  
Outer Sphere ◽  
Alcohol Concentration ◽  
Kinetics And Mechanism ◽  
Solvent Structure ◽  
Influence Of Ph ◽  
Sphere Mechanism

The kinetics and mechanism of the redox reactions of U3+ ions with mono- and dichloroacetic acids were studied. The influence of pH was observed mainly in the second case and led to the determination of the rate constants and activation parameters corresponding to two parallel steps, namely oxidation of U3+ with CHCl2COO- ions and oxidation of U3+ with CHCl2.COOH molecules. The influence of binary mixtures of water with methanol, ethanol, isopropanol, or tert-butenol on the reaction rate was followed. Increasing alcohol concentration influences the rate constant not only through changing dielectric constant and solvation of the reactants but also through a change of the solvent structure which plays a role in reactions with an outer sphere mechanism of the electron transfer.

Determination of rate constants of redox reactions of second order from current-less potential-time curves by a simplified graphical-numerical method

1983 ◽  
Vol 48 (5) ◽  
pp. 1358-1367 ◽  
Author(s):  
Antonín Tockstein ◽  
František Skopal
Keyword(s):  
Numerical Method ◽  
Explicit Form ◽  
Rate Constant ◽  
Optimization Algorithm ◽  
Rate Constants ◽  
Redox Reactions ◽  
Second Order ◽  
Wide Region ◽  
Recurrent Formula

A method for constructing curves is proposed that are linear in a wide region and from whose slopes it is possible to determine the rate constant, if a parameter, θ, is calculated numerically from a rapidly converging recurrent formula or from its explicit form. The values of rate constants and parameter θ thus simply found are compared with those found by an optimization algorithm on a computer; the deviations do not exceed ±10%.

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