1. Antioxidants & Free radicals

3. What are Reactive Oxygen Species?
ROS also known as Free oxygen radicals
Any molecule with an unpaired electron
Extremely chemically reactive
Damage cell membranes
Responsible for more than 100 human diseases
Aging, cancer, heart attacks, stroke and arthritis
Some beneficial effects

4. How are ROS Formed?
Primary source is our body during energy production
Environmental contaminants
Ionizing and ultraviolet radiation
Prolonged low blood flow states (atherosclerosis, heart attacks and stroke)
Diet (fatty and processed foods)
Low levels of antioxidants

5. Protection from ROS Damage
Superoxide dismutase
Catalase
Glutathion
Antioxidants in diet
Supplementation

6. Aging and Effect on Antioxidant Enzymes
Significant decline in SOD
Significant decline in catalase and glutathione
Significant decline in energy production
Cellular, tissue and system aging and failure

7. Scientific Support for Antioxidants
Animals with longer life spans have higher antioxidant levels
Dietary increase in antioxidants increase life span
Caloric restriction (reduces ROS formation) leads to significantly increased life span

8. Questions asked What are free radicals? Types of free radicals
Sources of free radicals
Oxygen metabolism

9. Discussion on oxidative damage and oxidative stress
What is antioxidant?
Natural free radical defense systems
What are Phytochemicals?

10. Functional food or Neutraceuticals
Nutrients
Non-nutrients
Energy, building
materials
Factors regulating
metabolism
Phyto-
chemicals
pigments
Antioxidants
Fibers
Other food
components
Lipid
Protein
Carbo-
hydrate
Water
Vitamins
Minerals
Zn, Se
C, E, b-Car
EFA &
non-EFA
EAA &
non-EAA
Glucose
Functional food or Neutraceuticals
Cys
GSH

11. Free radical-Mediated Diseases
Diseases of the old -
Chronic and degenerative diseases
(diabetes, cataracts, Alzheimer’s disease, cancers, cardiovascular disease, and aging)
Diseases of the young and innocent -
Acute and immature diseases
(Eyes: retinopathy of prematurity, Lung: bronchopulmonary displasia, Brain: cerebral pulsy, Pancreas: Type 1 diabetes)

12. What are free radicals?
Any molecule containing one or more unpaired electrons

13. Types of Free Radicals Reactive Oxygen Species (ROS) -
Reactive Nitrogen Species (RNS) - NO.
Reactive Metabolites or Intermediates
- metabolic activation of drugs, toxins, pollutants, cigarette smokes, etc.

14. Reactive Oxygen Species (ROS)
Superoxide (O2.-)
Hydrogen Peroxide (H2O2)
Hydroxyl Radical (OH.) - product of Fenton reaction catalyzed by free Fe and Cu
Singlet Oxygen (1DgO2) - oxygen at an excited state, requiring photosensitizers and photons

15. Sources of oxygen free radicals
In mitochondria:
- generation of energy - ATP
- glucose, fatty acids, amino acids
- O2 2H2O
4e-
- leakage of O2-. (superoxide)
H2O2 (hydrogen peroxide)

16. In Smooth Endoplasmic Reticulum (microsome)
- detoxification (cytochrome P-450s)
- toxins, drugs and xenobiotics
- O2 + RH R-OH and H2O
- leakage of O2-.
- metabolic activation - X.

17. In Peroxisomes
- containing oxidases for degradation of various substrates
- glucose, amino acids, xanthine, etc.
- requires O2
- byproduct is H2O2

18. In Cytoplasm
- nitric oxide (NO.) production from Arginine
- functions as a biological messenger
- in brain, vascular endothelial cells, and macrophages
- NO. + O2-. ONOO. (peroxynitrite)

19. NO: a Biological Messenger
NO is a neurotransmitter (brain- bNOS)
NO regulates blood pressure (vascular endothelial cells- eNOS)
NO is a cytotoxic agent (macrophages- iNOS)

20. Production of Singlet Oxygen
- photosensitizers in the biological system
(bilirubin, riboflavin, retinal, porphyrin)
- requires light , O2 and photosensitizers
- chlorophyll in photosynthesis
- photodynamic therapy

21. Antioxidants
Prevents the transfer of electron from O2 to organic molecules
Stabilizes free radicals
Terminates free radical reactions

22. Free Radical Defense System
Antioxidant Enzymes
Antioxidant Quenchers
Antioxidant from Foods – nutrients/non-nutrients

23. Antioxidant Enzymes
Superoxide Dismutase (SOD) – to get rid of superoxide produced from electron transport chain, the product is hydrogen peroxide.
MnSOD (mitochondria).
CuZn SOD (cytosol).

24. Oxygen Radical Defense Enzymes
GSH
Peroxidase
CuZnSOD
O2•¯
H2O2
H2O + O2
Fe2+
Mn SOD
Catalase
OH•

25. Antioxidant Enzymes - 2
Glutathione Peroxidase (GSH PX) – to get rid of hydrogen peroxide (H2O2) and some lipid peroxide. It requires reduced glutathione (GSH) as substrate and produces oxidized glutathione (GSSG) as product. A cytosolic enzyme.

26. Functions of GSH-dependent Enzymes
L-OH
H2O
GSSG
NADPH
GSH Px
GSH--Rx
L-OOH
H2O2
GSH
NADP+ X.
GSH-TR
GSX
X-Mercapturic Acid

27. Glutathione GSH is a tripeptide, g-glutamyl-cysteinyl-glycine
The sulfur atom of the cysteine moiety is the reactive site which provides electrons
GSH is stable because the g bond in glutamyl-cysteine (not the a peptide bond) is resistant to cellular peptidases

28. Glutathione
GSH is the most abundant non-protein thiol in mammalian cells
GSH is a substrate for two enzymes that are responsible for detoxification and antioxidation.
Other physiological roles including cysteine storage and transport, prostaglandin metabolism, immune function, cell proliferation and redox balance
Glutathione is the most abundant non-protein thiol in mammalian cells. In addition to function in the detoxification and antioxidation, GSH also has other physiological roles including cysteine storage and transport, prostaglandin metabolism, immune function, cell proliferation and redox balance.

29. Glutathione Synthesis
Protein
Methionine
Cysteine
Glutamate
g-Glutamylcysteine
Protein provides the supply of cysteine in the GSH synthesis. Cysteine is also the limiting amino acid in the synthesis. So when dietary protein level or the body protein status is low, cysteine supply would be limited and GSH synthesis would be reduced.
Glycine
GSH

30. Antioxidant Enzymes - 3
Catalase –to get rid of hydrogen peroxide produced in peroxisome.

31. Antioxidant Quenchers
Cellular proteins which chelate pro-oxidant minerals (iron and copper or others)
Transferrin – iron transport protein
Ferritin – iron storage protein
Metallothionein – minerals and heavy metals (Zn/Cu/Cd/Hg)
Ceruloplasmin – copper transport and storage

32. Antioxidants From Food
Antioxidant nutrients – vitamin E, vitamin C, (vitamin A?), beta-carotene
Phytochemicals – antioxidants from plants

34. Discovery of Other Functions of Phytochemicals
Anti-oxidant
Anti-inflammatory
Anti-estrogenic
Anti-allergic
Anti-cholesterolemic
Anti-hemorrhagic
Anti-mutagenic
Anti-neoplastic