Antioxidants

• What are the unstable molecules with unpaired electrons?

  Reactive oxygen species
• What are rhe substances that counteract the effects of ROS?

  Antioxidants
• What are the compounds of organic substances with antioxidant properties?


  Phenolic compounds
• Heterolytic bond cleavage is a type of chemical bond breaking where the shared pair of electrons in the bond goes to one of the atoms, resulting in the formation of ions
• Covalent bonding is the sharing of electrons between atoms in a chemical reaction.
• What is the dissociation of a molecular bond by a process where each of the fragments retains one of the originally bonded electrons?

  Homolysis
• What is the molecule that contains at least one unpaired electron?

  Radical molecule
• Free radical are reactive species with odd numbers of electron
• Hydrogen Peroxide

  Produced by the enzyme NADPH oxidase during phagocytosis.
• Superoxide

  Typically formed by the electron transport chain in mitochondria.
• What is a state of imbalance where the production of ROS exceeds the body's ability to neutralize them with antioxidants?

  Oxidative stress
• Superoxide is formed by one-electron reduction of molecular oxygen
• Superoxide is converted to hydrogen peroxide by superoxide dismutase
• Hydrogen peroxide is converted to water by catalase or by glutathione peroxidase
• Convertion of hydrogen peroxide to water require GSH as the reducing substrate
• Subsequent H2O accumulation may oxidize cysteine residues in protein, affect their redox states and functions, and regulate related signaling pathway
• Glutathione (GSH)


  A tripeptide and endogenous antioxidant that is recycled by glutathione reductase to maintain cellular homeostasis.
• RBOHs (Respiratory Burst Oxidase Homologs)


  A family of enzymes that produce ROS as a defense response against pathogens and insect attacks.
• OS - A

  A) LDL - Ox-LDL

  B) VCAM

  C) chemokines

  D) Monocytes will become macrophages

  E) engulf ox-LDL

  F) Foam cell

  G) T-cells

  H) TNF-alpha, INF-gamma

  I) Inflammation

  
• Low-density lipoproteins (LDLs) in the bloodstream are oxidized due to oxidative stress, transforming them into oxidized LDLs
• What are the major component of atherosclerotic plaques?

  Foam cells
• Free radicals have the potential to damage cells in our bodies by stealing an electron, leaving the cell unbalanced
• Vitamin E


  Fat-soluble antioxidant that protects cells from oxidative stress
• Vitamin C


  Water-soluble antioxidant that protects cells from hydrogen peroxide
• Chelation


  Antioxidants bind to metal ions to prevent oxidative reactions
• What are the compounds capable to either delay or inhibit the oxidation processes?

  Antioxidant
• Enzymatic system

  Biological system inside the cell
• Superoxide dismutase


  • Converts superoxide anion into hydrogen peroxide
• Catalase


  • Catalyzes the conversion of H₁₂O₂ to H₂O and O₂
• Glutathione peroxidase


  • Similar function with catalase, found in the human red blood cell
• Glutathione reductase


  • Catalyzes the reaction of GSSH <> GSH
• Scavenging


  The act of removing or neutralizing free radicals.
• Hydrogen Peroxide Scavenging Assay


  A laboratory test to evaluate the ability of a substance to remove free radicals, including hydrogen peroxide.
• Decay of H

  The decrease in concentration of hydrogen peroxide (H₂O₂) over time, monitored through changes in absorbance at 230 nm.
• Absorbance at 230 nm


  A measure of the light absorption of H₂O₂ at a specific wavelength, which decreases as the H₂O₂ is reduced.
• Phosphate Buffer at pH 7.4


  A buffer used in the hydrogen peroxide assay to maintain optimal conditions for the reaction, with a pH of 7.4.
• Percentage Inhibition


  A unit of scavenging activity, representing the percentage reduction in hydrogen peroxide (H₂O₂) concentration in the presence of the antioxidant compared to the control.
• Ferric Reducing-Antioxidant Power Assay


  A method that measures the ability of an antioxidant to reduce ferric iron (Fe³⁺) to ferrous iron (Fe²⁺) and its association with 2,4,6-Tripyridyl-s-triazine (TPTZ) under acidic conditions.
• Ferric Iron


  A form of iron that can be reduced by antioxidants.
• Ferrous Iron 


  A form of iron that is more easily reducible and commonly used as a marker for antioxidant activity.