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Nathan Goodyear

Oxidative Damage to DNA Constituents by Iron-mediated Fenton Reactions - 0 views

www.jbc.org/...21167.long

Fenton reaction

shared by Nathan Goodyear on 07 Jul 19 - No Cached
  • Nathan Goodyear on 07 Jul 19
     
    Older article on Fenton reaction.
Nathan Goodyear

Ascorbic acid: Chemistry, biology and the treatment of cancer - 0 views

www.ncbi.nlm.nih.gov/...PMC3608474

Fenton reaction ferritin vitamin C Fe cancer

shared by Nathan Goodyear on 07 Jul 19 - No Cached
  • iron and ascorbate has long been used as an oxidizing system; the combination of these two reagents is referred to as the Udenfriend system
  • ascorbate serves as a reducing cofactor for many enzymes
  • uptake of ascorbate from the intestinal tract is very tightly controlled
  • ...11 more annotations...
  • pharmacokinetic data indicate that intravenous administration of ascorbate can bypass this tight control resulting in highly elevated plasma levels
  • ascorbate readily oxidizes to produce H2O2, pharmacological ascorbate has been proposed as a prodrug for the delivery of H2O2 to tumors
  • Ascorbate is an excellent reducing agent and readily undergoes two consecutive, one-electron oxidations to form ascorbate radical (Asc•−) and dehydroascorbic acid (DHA)
  • Ascorbate oxidizes readily. The rate of oxidation is dependent on pH and is accelerated by catalytic metals
  • In near-neutral buffers with contaminating metals, the oxidation and subsequent loss of ascorbate can be very rapid
  • Ascorbate is required for maintaining iron in the ferrous state
  • In the presence of catalytic metal ions, ascorbate can also exert pro-oxidant effects
  • Ascorbate is an excellent one-electron reducing agent that can reduce ferric (Fe3+) to ferrous (Fe2+) iron, while being oxidized to ascorbate radical
  • In a classic Fenton reaction, Fe2+ reacts with H2O2 to generate Fe3+ and the very oxidizing hydroxyl radical
  • e presence of ascorbate can allow the recycling of Fe3+ back to Fe2+, which in turn will catalyze the formation of highly reactive oxidants from H2O2
  • Depending on concentrations, the effects of ascorbate on models of lipid peroxidation can be pro- or antioxidant
  • Nathan Goodyear on 07 Jul 19
     
    ferritin released enhanced pharmacologic ascorbate induced-cytotoxicity, indicating that ferritin with high iron-saturation could be a source of catalytic iron. Consistent with this, ascorbate has also been shown to be capable of releasing iron from cellular ferritin
Nathan Goodyear

Mechanisms of the pH- and Oxygen-Dependent Oxidation Activities of Artesunate - 0 views

www.jstage.jst.go.jp/...en

artesunate cancer Fenton reaction Fe

shared by Nathan Goodyear on 07 Jul 19 - No Cached
  • Nathan Goodyear on 07 Jul 19
     
    Artesunate reduces Fe3+ to Fe2+ via the fenton reaction. Similar to vitamin C.
Nathan Goodyear

Role of iron in carcinogenesis: Cancer as a ferrotoxic disease - Toyokuni - 2009 - Canc... - 0 views

onlinelibrary.wiley.com/...j.1349-7006.2008.01001.x

ferritin cancer fenton reaction

shared by Nathan Goodyear on 01 Apr 20 - No Cached
  • Nathan Goodyear on 01 Apr 20
     
    Fe, fenton reaction, cancer... very interesting read
Nathan Goodyear

High-Dose Vitamin C for Cancer Therapy - PMC - 0 views

www.ncbi.nlm.nih.gov/...PMC9231292

vitamin C cancer

shared by Nathan Goodyear on 27 Jul 22 - No Cached
  • diabetes [8], atherosclerosis [9], the common cold [10], cataracts [11], glaucoma [12], macular degeneration [13], stroke [14], heart disease [15], COVID-19 [16], and cancer.
  • 1–5% of the Vit-C inside the human cells
  • interaction between Fe(II) and H2O2 produces OH− through the Fenton reaction
  • ...35 more annotations...
  • metabolic activity, oxygen transport, and DNA synthesis
  • Iron is found in the human body in the form of haemoglobin in red blood cells and growing erythroid cells.
  • macrophages contain considerable quantities of iron
  • iron is taken up by the majority of cells in the form of a transferrin (Tf)-Fe(III) complex that binds to the cell surface receptor transferrin receptor 1 (TfR1)
  • excess iron is retained in the liver cells
  • the endosomal six transmembrane epithelial antigen of the prostate 3 (STEAP3) reduces Fe(III) (ferric ion) to Fe(II) (ferrous ion), which is subsequently transferred across the endosomal membrane by divalent metal transporter 1 (DMT1)
  • labile iron pool (LIP)
  • LIP is toxic to the cells owing to the production of massive amounts of ROS.
  • DHA is quickly converted to Vit-C within the cell, by interacting with reduced glutathione (GSH) [45,46,47]. NADPH then recycles the oxidized glutathione (glutathione disulfide (GSSG)) and converts it back into GSH
  • Fe(II) catalyzes the formation of OH• and OH− during the interaction between H2O2 and O2•− (Haber–Weiss reaction)
  • Ascorbate can efficiently reduce free iron, thus recycling the cellular Fe(II)/Fe(III) to produce more OH• from H2O2 than can be generated during the Fenton reaction, which ultimately leads to lipid, protein, and DNA oxidation
  • Vit-C-stimulated iron absorption
  • reduce cellular iron efflux
  • high-dose Vit-C may elevate cellular LIP concentrations
  • ascorbate enhanced cancer cell LIP specifically by generating H2O2
  • Vit-C produces H2O2 extracellularly, which in turn inhibits tumor cells immediately
  • tumor cells have a need for readily available Fe(II) to survive and proliferate.
  • Tf has been recognized to sequester most labile Fe(II) in vivo
  • Asc•− and H2O2 were generated in vivo upon i.v Vit-C administration of around 0.5 g/kg of body weight and that the generation was Vit-C-dose reliant
  • free irons, especially Fe(II), increase Vit-C autoxidation, leading to H2O2 production
  • iron metabolism is altered in malignancies
  • increase in the expression of various iron-intake pathways or the downregulation of iron exporter proteins and storage pathways
  • Fe(II) ion in breast cancer cells is almost double that in normal breast tissues
  • macrophages in the cancer microenvironment have been revealed to increase iron shedding
  • Advanced breast tumor patients had substantially greater Fe(II) levels in their blood than the control groups without the disease
  • increased the amount of LIP inside the cells through transferrin receptor (TfR)
  • Warburg effect, or metabolic reprogramming,
  • Warburg effect is aided by KRAS or BRAF mutations
  • Vit-C is supplied, it oxidizes to DHA, and then is readily transported by GLUT-1 in mutant cells of KRAS or BRAF competing with glucose [46]. DHA is quickly converted into ascorbate inside the cell by NADPH and GSH [46,107]. This decrease reduces the concentration of cytosolic antioxidants and raises the intracellular ROS amounts
  • increased ROS inactivates glyceraldehyde 3-phosphate dehydrogenase (GAPDH)
  • ROS activates poly (ADP-ribose) polymerase (PARP), which depletes NAD+ (a critical co-factor of GAPDH); thus, further reducing the GAPDH associated with a multifaceted metabolic rewiring
  • Hindering GAPDH can result in an “energy crisis”, due to the decrease in ATP production
  • high-dose Vit-C recruited metabolites and increased the enzymatic activity in the pentose phosphate pathway (PPP), blocked the tri-carboxylic acid (TCA) cycle, and increased oxygen uptake, disrupting the intracellular metabolic balance and resulting in irreversible cell death, due to an energy crisis
  • mega-dose Vit-C influences energy metabolism by producing tremendous amounts of H2O2
  • Due to its great volatility at neutral pH [76], bolus therapy with mega-dose DHA has only transitory effects on tumor cells, both in vitro and in vivo.
Nathan Goodyear

Lipid Peroxidation: Production, Metabolism, and Signaling Mechanisms of Malondialdehyde... - 0 views

www.hindawi.com/...360438

MDA malondialdehyde peroxidation oxidative stress free radicals

shared by Nathan Goodyear on 05 Dec 17 - No Cached
  • Hydroxyl radicals cause oxidative damage to cells because they unspecifically attack biomolecules [22] located less than a few nanometres from its site of generation and are involved in cellular disorders such as neurodegeneration [23, 24], cardiovascular disease [25], and cancer [26, 27].
  • It is generally assumed that in biological systems is formed through redox cycling by Fenton reaction, where free iron (Fe2+) reacts with hydrogen peroxide (H2O2) and the Haber-Weiss reaction that results in the production of Fe2+ when superoxide reacts with ferric iron (Fe3+)
  • other transition-metal including Cu, Ni, Co, and V can be responsible for formation in living cells
  • ...20 more annotations...
  • The hydroperoxyl radical () plays an important role in the chemistry of lipid peroxidation
  • The is a much stronger oxidant than superoxide anion-radical
  • Lipid peroxidation can be described generally as a process under which oxidants such as free radicals or nonradical species attack lipids containing carbon-carbon double bond(s), especially polyunsaturated fatty acids (PUFAs) that involve hydrogen abstraction from a carbon, with oxygen insertion resulting in lipid peroxyl radicals and hydroperoxides as described previously
  • under medium or high lipid peroxidation rates (toxic conditions) the extent of oxidative damage overwhelms repair capacity, and the cells induce apoptosis or necrosis programmed cell death
  • The overall process of lipid peroxidation consists of three steps: initiation, propagation, and termination
  • Once lipid peroxidation is initiated, a propagation of chain reactions will take place until termination products are produced.
  • The main primary products of lipid peroxidation are lipid hydroperoxides (LOOH)
  • Among the many different aldehydes which can be formed as secondary products during lipid peroxidation, malondialdehyde (MDA), propanal, hexanal, and 4-hydroxynonenal (4-HNE) have been extensively studied
  • MDA has been widely used for many years as a convenient biomarker for lipid peroxidation of omega-3 and omega-6 fatty acids because of its facile reaction with thiobarbituric acid (TBA)
  • MDA is one of the most popular and reliable markers that determine oxidative stress in clinical situations [53], and due to MDA’s high reactivity and toxicity underlying the fact that this molecule is very relevant to biomedical research community
  • 4-HNE is considered as “second toxic messengers of free radicals,” and also as “one of the most physiologically active lipid peroxides,” “one of major generators of oxidative stress,” “a chemotactic aldehydic end-product of lipid peroxidation,” and a “major lipid peroxidation product”
  • MDA is an end-product generated by decomposition of arachidonic acid and larger PUFAs
  • Identifying in vivo MDA production and its role in biology is important as indicated by the extensive literature on the compound (over 15 800 articles in the PubMed database using the keyword “malondialdehyde lipid peroxidation” in December 2013)
  • MDA reactivity is pH-dependent
  • When pH decreases MDA exists as beta-hydroxyacrolein and its reactivity increases
  • MAA adducts are shown to be highly immunogenic [177–181]. MDA adducts are biologically important because they can participate in secondary deleterious reactions (e.g., crosslinking) by promoting intramolecular or intermolecular protein/DNA crosslinking that may induce profound alteration in the biochemical properties of biomolecules and accumulate during aging and in chronic diseases
  • MDA is an important contributor to DNA damage and mutation
  • This MDA-induced DNA alteration may contribute significantly to cancer and other genetic diseases.
  • Dietary intake of certain antioxidants such as vitamins was associated with reduced levels of markers of DNA oxidation (M1dG and 8-oxodG) measured in peripheral white blood cells of healthy subjects, which could contribute to the protective role of vitamins on cancer risk
  • 4-HNE is an extraordinarily reactive compound
  • Nathan Goodyear on 05 Dec 17
     
    Great review of lipid peroxidation
Nathan Goodyear

Fenton Reactions and Cancer - 0 views

csbl.bmb.uga.edu/...index.html

cancer fenton reaction

shared by Nathan Goodyear on 31 Mar 20 - No Cached
  • Nathan Goodyear on 31 Mar 20
     
    To be read
Nathan Goodyear

Frontiers | Importance of Iron Complexation for Fenton-Mediated Hydroxyl Radical Produc... - 0 views

www.frontiersin.org/...full

Fenton reaction

shared by Nathan Goodyear on 07 Jul 19 - No Cached
  • Nathan Goodyear on 07 Jul 19
     
    Acidic pH required for OH and Fe+3 production. Higher ph, more basic, likely results in other products.
Nathan Goodyear

Iron chelators as antimalarial agents: in vitro activity of dicatecholate against Plasm... - 0 views

watermark.silverchair.com/dkf104.pdf

artesunate vitamin C fenton reaction doxycycline

shared by Nathan Goodyear on 07 Jul 19 - No Cached
  • Nathan Goodyear on 07 Jul 19
     
    Study finds that vitamin C inhibits pro-oxidant effects of artesunate at doses of 400 microM/L; Same with doxycycline. The problem here is that that translates to 5 mg/dL of vitamin C. Studies have shown that vitamin C's effect in cancer is attributable in part to its dose and the presence of metals.
Nathan Goodyear

Molecular mechanisms of ferroptosis and its role in cancer therapy - 0 views

www.ncbi.nlm.nih.gov/...PMC6653007

ferroptosis fenton reaction cancer

shared by Nathan Goodyear on 31 Mar 20 - No Cached
  • Nathan Goodyear on 31 Mar 20
     
    Nice review of ferroptosis.
Nathan Goodyear

New promising developments for potential therapeutic applications of high-dose ascorbat... - 0 views

www.sciencedirect.com/...S1658387620301746

vitamin C HIF-1 SVCT hypoxia redox GLUT cancer fenton reaction HIF-1alpha

shared by Nathan Goodyear on 01 Apr 21 - No Cached
  • Nathan Goodyear on 01 Apr 21
     
    Awesome review.
Nathan Goodyear

Utilization of Pharmacological Ascorbate to Enhance Hydrogen Peroxide-Mediated Radiosen... - 0 views

www.ncbi.nlm.nih.gov/...PMC8509557

radiation fenton reaction High dose IV vitamin C vitamin C ascorbic acid high dose vitamin C H2O2 pharmacologic vitamin C

shared by Nathan Goodyear on 11 Aug 22 - No Cached
  • Nathan Goodyear on 11 Aug 22
     
    Conclusion: the data presented in this review show synergistically increased DNA damage with combination treatment of RT and P-AscH−, associated with H2O2 formation
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