The Chemistry and Application of Natural Antioxidants

1
KoSFoST
FST-OSU
11th World Congress of Food Science Technology
2
Chemistry and Application of Antioxidants

• David B. Min
•  
• The Ohio State University
• Columbus, Ohio, USA

3
Effects of Lipid Oxidation

• Flavor Quality Loss Rancid flavor
• Changes of color and texture
• Consumer Acceptance
• Economic
  loss
• Nutritional Quality Loss Essential Fatty Acids
• 
  Vitamins
• Health Risks Growth Retardation
• Heart
  Diseases

4
Activation Energy for Chemical Reaction

Reactions
Activation Energy

(kcal/mol) Protein Denaturation
100 Nonenzymatic Browning
Reaction 50 Enzyme Catalyzed
Reaction 10-15 Lipid
Oxidation
10-15
5
Lipid Foods
6
History of Oxygen

• Oxygen - Priestly in 1772.
• Triplet oxygen - Millikan in 1928.
• Singlet oxygen - Herzberg in 1934.

7
Mechanisms of Lipid Oxidation

• Triplet oxygen oxidation
• Singlet oxygen oxidation

8
Triplet Oxygen Oxidation
9
Molecular Orbital of Triplet Oxygen
10
Bond Energy of Carbon and Hydrogen
(kcal/mol)
100
75
50
C
H
C
H
C
H
C
H
C
H
C
H
(
C
H
)
C
O
O
H
C
H
(
C
H
)
C
H
2
2
2
6
2
2
3
3
C
H
(
C
H
)
C
O
O
H
C
H
C
H
Stearic acid Oleic acid Linoleic acid
Linolenic acid
3
2
14
2
2
(
C
H
)
(
C
H
)
C
H
C
H
C
O
O
H
C
H
C
H
2
6
2
7
2
3
(
C
H
)
C
H
C
H
(
C
H
)
C
O
O
H
C
H
C
H
C
H
C
H
2
4
2
7
3
2
C
H
C
H
C
H
C
H
C
H
C
H
(
C
H
)
C
O
O
H
C
H
C
H
C
H
C
H
2
2
2
7
3
2
11
Initiation of Triplet Oxygen Oxidation
Initiation of autoxidation occurs when hydrogen
atom at ?-methylene group in double bonds is
removed to form an alkyl radical (R?).
(
C
H
)
C
H
C
H
(
C
H
)
C
O
O
H
C
H
C
H
C
H
C
H
2
4
2
7
3
2
RH
R?
H?

12
Propagation
ROO ?

R?
3O2
ROOH

R?
ROO ?
RH

? OH

RO ?
ROOH


RH
RO ?
ROH
R ?
13
Termination
R-R

R ?
R ?
2RO ?
ROOR
R ?
ROOR
ROO ?

R ?

RO ?
ROR

ROOR
O2

ROO ?
ROO ?
14
Pentane from Linoleic Acid by Triplet Oxygen
Oxidation
14
13 12 11 10 9
C
H
C
H
C
H
C
H
C
H
C
H
C
H
R
(
C
H
)
C
H
2
2
2
2
3
3
INITIATION
- H

(METAL)
13 12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2

3O
2
13 12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2
O
O
PROPAGATION

H

R (CH2)6-COOH
15
13 12 11 10 9
C
H
C
H
C
H
C
H
C
H
C
H
R
(
C
H
)
C
H
2
2
4
3
O
O
- OH

H
13 12 11 10 9
C
H
R
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
2
2
4
3
O

O

C
C
H
C
H
C
H
C
H
C
H
R
C
H
(
C
H
)
C
H

2
3
2
3
2
H
TERMINATION
H

C
H
(
C
H
)
C
H
(PENTANE)
3
2
3
3
R (CH2)6-COOH
16
Singlet Oxygen Oxidation
17
Molecular Orbital of Singlet Oxygen
?
18
Singlet Oxygen Formation
Enzymes
RCOO RCOO
3O2 Sensitizer
Endoperoxides
H2O2 OCI-
Ozone
1O2
H2O2 O2 -
OH- O2 -
H2O2 HO2 -
O2 -
O2 - O2 -
O2 - Y
19
Photosensitizers in Foods

• Chlorophyll
• Protoporphyrine
• Riboflavin
• Red No. 3

20
Formation of 1O2 by Sensitizers
Excited State
1Sen
K1- 20?108/sec ISC
Fluorescence K 2?108/sec
3Sen
hv
K1- 3?109/sec
Phosphorescence
3O2
K10- 104/sec
1Sen
Singlet Oxygen, 1O2
Ground State
21
Reversion Flavor Compounds from Soybean Oil
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
3
2
2
3
2
2
O
O
2-(2-pentenyl)-furan
2-(1-pentenyl)-furan
22
Reversion Flavor from Linolenic Acid by Singlet
Oxygen Oxidation
1O2
C
H
C
H
C
O
O
H
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
2
2
6
2
3
2
2
O
O


C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
2
3
2
2
1O2
O
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
2
3
2
2
O
O
O
23
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
2
3
2
2

O
O
O
H
- OH

C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
2
3
2
2

O
O

C
H
C
H
C
H
C
H
C
H
C
C
H
C
H
C
H
3
2
2
2
2
O
O
C
H
C
H
C
H
C
H
C
H
C
C
H
C
H
C
H
3
2
2
O
H
O
H
- H2O
2-(2-pentenyl)-furan
C
H
C
H
C
H
C
H
C
H
3
2
2
O
24
Reaction of 3O2 and 1O2 with Linoleic Acid
O
O
H
3O2

R
R
'
R
R
'
Conjugated
- H
R
R
'
HOO

3O2
R
R
'
R
R
'
Conjugated
O
O
H
R
'
R
O
R
R
'
1O2
H
O
Conjugated
R
R
'
O
O
H
R
'
R'
R
R
O
H
O
Nonconjugated
25
Reaction Rates of Lipid Oxidation
R? 3O2 K109 M-1sec-1 ROO? Oleic Acid K1
M-1sec-1 ROO? Linoleic Acid K60
M-1sec-1 ROO? Linolenic Acid K120
M-1sec-1 ROO? ROO? K105-107
M-1sec-1 R? Antioxidants K 107
M-1sec-1 RH 1O2 K105 M-1sec-1
26
Relative Reaction Rates of 3O2 and 1O2 with
Oleic, Linoleic, and Linolenic Acids
Oleic Linoleic Linolenic Acid Acid Acid
Triplet oxygen 1 27 77
Singlet oxygen 3 ?104 4 ?104 7 ?104
27
Lipoxygenase Oxidation
28
Enzymatic Oxidation
Poly unsaturated fatty acids (a cis,
cis-1,4-pentadiene unit)
Lipoxygenase
Hydropeorxide at the ?-6 position of unsaturated
fatty acid
29
Control of Lipid Oxidation

• Application of antioxidants
• Elimination of oxygen by nitrogen flushing or
  
• vacuum packaging
• Elimination of photosensitizers
• Denaturation of lipoxygenase
• Low temperature and dark storage

30
.
R, RO, ROO, O-2 1O2, -OH, H2O2,Cu, Fe
Antioxidants
Prooxidant Jail
R, RO, ROO, 1O2, O-2, -OH, H2O2, Cu, Fe
31
Function of Antioxidant on Lipid Oxidation

• Inhibits or slows the formation of free alkyl
  
• radicals in the initiation step
• Interrupts the propagation of free radical chain
  
• Delays the start or slows the chemical reaction
• rate of lipid oxidation.

32
Types of Antioxidants

• Hydrogen donating compounds
• Singlet oxygen quenchers
• Metal chelators
• Enzymes
• Oxygen scavengers

33
Hydrogen Donating Antioxidants
34
Hydrogen Donating Antioxidant

• Should have lower reduction potential than the
  
• reduction potential of polyunsaturated fatty
• acid (E 600 mV)
• Should donate a hydrogen to alkoxyl (E 1600
• mV) or peroxyl (E 1000 mV) radicals

35
Standard One-Electron Reduction Potential
Compounds E (mV)
HO , H / H2O 2310 RO , H /
ROH 1600 ROO , H / ROOH 1000 PUFA , H
/ PUFA 600 Catechol , H / Catechol 530 ?-
Tocopheroxyl , H / ?- Tocopherol 500 Ascorbate-
, H / Ascorbate 282

36
Characteristics of Hydrogen Donating Antioxidants

• The major hydrogen donating antioxidants are
  monohydroxy or polyhydroxy phenolic compounds
  with various ring substitutions.
• The antioxidant free radical does not initiate
  another free radical due to the stabilization of
  radical by delocalization.

37
Resonance of Antioxidant Radicals
O
H
C
(
C
H
)
3
3
O
C
H
3
RH , ROH , ROOH
R , RO , ROO



.
O
O
.
C
(
C
H
)
C
(
C
H
)
3
3
3
3
O
C
H
O
C
H
3
3
R , RO , ROO



O
O
C
(
C
H
)
.
C
(
C
H
)
3
3
3
3
.
O
C
H
O
C
H
3
3
38
Effectiveness of Antioxidants

• The difference of one-electron reduction
  potential
• between lipid radical and antioxidant radical.
• 2. The stability of antioxidant radical.
• The resonance delocalization
• Further oxidation of antioxidant radicals

39
Synthetic Antioxidants
40
Natural Antioxidants

• Benefits
• Health implication
• Limits
• Characteristic flavor
• Safety test required

41
Tocopherols
R
1
H
O
C
H
C
H
C
H
C
H
3
3
3
3
R
C
H
O
2
3
R
3
Trivial Name Chemical Name R1 R2 R3 ?-Tocopherol
5,7,8-Trimethyltocol CH3 CH3 CH3 ?-Tocopherol 5
,8-Dimethyltocol CH3 H CH3 ?-Tocopherol 7,8-Dimet
hyltocol H CH3 CH3 ?-Tocopherol 8-Methyltocol H
H CH3
42
Antioxidant Mechanism of Tocopherol

• Transfer of phenolic hydrogen
• Scavenging of singlet oxygen

43
Resonance of ?- Tocopherol Radicals
C
H
3
H
O
C
H
C
H
C
H
?-Tocopherol
C
H
3
3
3
3
H
C
O
3
C
H
3
R?, RO ?, or ROO ?
RH , ROH , ROOH
C
H
3
C
H
3
?
O
O
C
H
3
C
H
3
?
H
C
O
C
H
3
H
C
C
H
16
33
O
3
16
33
C
H
3
C
H
3
R?, RO ?, or ROO ?
C
H
C
H
3
3
O
?
O
C
H
C
H
?
3
3
H
C
C
H
C
H
O
C
H
3
O
3
16
33
16
33
C
H
C
H
3
3
44
Effects of Diet Tocopherol on the Content of
Tocopherol in Egg Yolk
45
Effects of Tocopherol on the Stability of Egg York
45
40
25?g Tocopherol / g yolk
35
45 ? g Tocopherol / g yolk
Control
30
50 ? g Tocopherol / g yolk
25
75 ? g Tocopherol / g yolk
20
Total Headspace Volatiles (? 1000)
15
10
5
0
0
2
4
6
8
Time (Days)
46
Ascorbic Acid

• Hydrogen donation to lipid radicals
• Quenching of singlet oxygen
• Removal of molecular oxygen
• Regenerate tocopherol radicals
• Prooxidant Reduce ferric iron to ferrous
  iron

47
Ascorbic Acid
C
H
O
H
C
H
O
H
2
2
H
H
C
C
O
H
O
H
O
O
O
O
- H
- H
H
H
R?, RO ?, ROO ?
R ?, RO ?, ROO ?

O
H
O
O
O
Dehydroascorbic acid
L-Ascorbic acid
48
Ascorbic Acid and Related Compounds
O
C
H
O
H
C
H
O
C
(
C
H
)
C
H
C
H
O
H
2
2
2
2
14
3
H
O
H
H
C
C
H
C
O
H
O
H
O
O
O
O
O
O
H
H
H
O
H
H
O
H
O
H
O
O
H
O
H
L-Ascorbic Acid
Erythorbic Acid
Ascorbic Palmitate
49
Synergistic Effectof Tocopherol Ascorbic Acid
50
Let us stand up and stretch
51
Singlet Oxygen Quencher
52
Singlet Oxygen Quenching Mechanism
ISC
A
3O2
hv
1Sen
1Sen
3Sen
1O2
AO2
Q
Kq
Kd
Q
Kox-Q
1Sen
1Sen
3O2
QO2
3O2
53
Carotenoids
C
H
O
b -
Apo - 8'- carotenal
Carotene
b -
O
Canthaxanthin
O
54
Effects of ?-Apo-8-Carotenal, ?-Carotene or
Canthaxanthin on the Soybean Oil Oxidative
Quality
Peroxide Value (meq/kg oil)
Storage Time (hr)
55
Singlet Oxygen Quenching Mechanism
ISC
A
3O2
hv
1Sen
1Sen
3Sen
1O2
AO2
Q
Kq
Kd
Q
Kox-Q
1Sen
1Sen
3O2
QO2
3O2
56
Quenching Mechanism of b-Carotene on Singlet
Oxygen Oxidation
1/ Peroxide (1/ M)
57
Singlet Oxygen Quenching Rates of Carotenoids
Carotenoids Number of Conjugated
Quenching Rate Double Bonds
Constants (M-1sec-1) ? -Apo-8-
carotenal 10
2.86 ? 109 ? - Carotene
11
4.60 ? 109 Canthaxanthin
13
1.12 ? 1010


58
Singlet Oxygen Quenching Rate of Carotenoids
Carotenoids Number of Conjugated
Rate Constants
Double Bonds (109
M-1sec-1) Astaxanthin 13
9.88 Isozeaxanthin
11
7.31 Zeaxanthin 11
7.03 Lycopene
11
6.89 Lutein 10
5.86
59
Singlet Oxygen Quenching Rates of Tocopherols
?-Tocopherol 2.70 ? 107 (M-1sec-1)
Singlet oxygen quenching ability ? gt ? gt ? gt ?
- Tocopherol
60
Singlet Oxygen Quenchers
Singlet Oxygen Quencher Quenching Rate
(M-1sec-1) ?-Carotene 4.60 ?
109 Ascorbic acid 1.08 ? 108 ?-Tocopherol
2.70 ? 107
61
Metal Chelators
62
Prooxidant Mechanisms of Metals

• Hydroperoxide decomposition to form
• peroxyl radical and alkoxyl radical.
• Fe3 ROOH Fe2 ROO H
• Fe2 ROOH Fe3 RO OH-

63
Prooxidant Mechanisms of Metals

• Formations of alkyl free radical by direct
  reaction
• Fe3 RH Fe2 R H
• Activation of oxygen for singlet oxygen
  formation
• Fe2 3O2 Fe3 O-2 1O2
• Formation of hydroxyl radical
• Fe2 H2O2 Fe3 OH- OH

64
Metal Chelators

• Phosphoric acid
• Citric acid
• Ascorbic acid
• Ethylene Diamine Tetra Acetate (EDTA)
• Amino acids and peptides
• Proteins such as transferrin, ovotransferrin

65
Mechanism of Metal Chelators

• Formation of complex ions or coordination
  compounds with metals
• Prevention of metal redox cycling
• Formation of insoluble metal complexes
• Steric hindrance of interactions between metals
  and
• lipid intermediates

66
Interaction of Chealator and Metal
O
C
O
C
H
O
2
C
C
H
2
N
O
C
H
2
M
C
H
2
O
N
C
H
C
C
H
2
2
O
O
C
O
Ethylene Diamine Tetra Acetate (EDTA)
67
Enzymatic Antioxidants
68
Glucose Oxidase/Catalase
Glucose Oxidase
2 Glucose 2O2 2H2O 2 Gluconic acid
2H2O2
Catalase
2H2O2 2H2O O2
Glucose Oxidase Catalase
2 Glucose O2 2 Gluconic acid
     


69
Superoxide Anion

• Superoxide anion participates in oxidative
  reactions
• Maintaining transition metals in their reduced
  active state
• Promoting the release of metals from proteins
• Producing singlet oxygen

Spontaneous Dismutation

-

2O
O

2H
1
H
O
2
2
2
2
70
Superoxide Dismutase

• Producing triplet oxygen from superoxide anion

-
Superoxide Dismutase


2O
O

2H
3
H
O
2
2
2
2
Catalase
2H
O
3

O
O
2H
2
2
2
2
71
Glutathione Peroxidase
Glutathione Peroxidase
H2O2 2GSH 2H2O GSSG
LOOH 2GSH
LOH H2O GSSG
Glutathione Peroxidase
GSH Reduced glutathione GSSH Oxidized
glutathione
72
Oxygen Scavengers
73
Oxygen Scavengers

• Ascorbic acid
• Ascorbic palmitate
• Erythorbic acid
• Sulfites

74
Oxygen Scavenger Mechanisms
C
H
O
H
2
H
C
O
H
O
O
½ O

H O

2
H
2
O
O
C
H
S
H
C
H
S
S
C
H
½ O
H O


2
2
3
3
3
O
O
O
O
H
H
O
S
2
H
O
S
O
H
O
75
Antioxidant Interactions

• Combination of metal chelator and free radical
• scavenging antioxidants
• Combination of different antioxidants like
• ?- tocopherol and ascorbic acid

76
Antioxidant Sources
77
Flavonoids
O
H
O
H
O
H
O
O
H
O
H
O
O
H
O
H
O
G
l
u
c
os
i
de
O
O
H
O
H
Quercetin Flavonols
Cyanidin-3-glucoside Anthocyanins
78
Flavonoids

• Secondary products of plant metabolism
• Metal chelating ability
• Superoxide anion scavengers
• Hydrogen donors
• Anthocyanines, catechins, flavones, flavonols,
  isoflavone, and proanthocyanidins

79
Vegetables
Cacao beans, Potato, Tomato, Spinach, Legumes,
Garlic, and Seaweed Polyphenolic compounds
80
Fruits

Wines Anthocyanin Polyphenolic compounds
81
Tea
O
H
O
H
O
H
O
H
O
O
O
H
H
O
O
H
O
H
O
H
O
H
O
H
Epigallocatechin
Epicatechin
82
Sesame Seed
O
O
O
O
O
O
O
O
H
O
H
O
C
H
3
Sesamol
Sesamolinol
83
Herb and Spice
Sage, Ginger, Green pepper, Lavender and Rosemary

O
H
C
H
3
H
O
O
C
H
3
C
O
C
H
H
C
3
3
Carnosoic Acid
Carnosol
O
H
H
O
O
C
O
H
O
O
H
O
Rosemarinic Acid
O
H
84
Reaction Rates of Carnosol and Carnosic Acidand
Peroxyl Radical
Carnosic acid

O
H
O
H
O
H
O
H
O
O
C
H
O
O
C


LOO
LOOH
3 ? 107 M-1s-1
H
H
Carnosol

O
H
O
H
O
H
O


O
O
LOO
LOOH
C
C
2 ? 106 M-1s-1
O
O
H
H
85
Soybean

• Chlorogenic acid, caffeic acid, ferulic acid -
• Metal chelation and singlet oxygen quenching
• Isoflavones
• Metal chelation and hydrogen donation

86
Soybean
C
O
O
H
H
O
O
H
O
R
O
2
O
H
O
H
O
H
Chlorogenic acid
1
Isoflavones R1 R2
Genistein OH OH Daidzein H OH
87
Korean Ginseng
88
Korean Ginseng
C
H
C
H
C
O
O
H
C
H
C
H
C
O
O
H
H
O
H
O
O
H
O
C
H
3
Caffeic acid
Ferulic acid
O
O
H
C
O
O
H
O
H
O
H
H
O
O
H
O
O
C
H
3
Vanillic acid
Kaempferol
89
Korean Ginseng

• Singlet oxygen quenchers Caffeic acidgt
  Kaempferol gtVanillic
• acid gt Salicylic acid gt Ferulic acid
• Linoleic acid in aqueous system under dark
  Kaempferol gt
• Maltol gt Vanillic acid gt Saponin gt Salicylic
  acid gt Ferulic acid
• Metal chelation activity Kaempferol gt Maltol gt
  Vanillic acid
• gt Ferulic acid gt Caffeic acid

90
Maillard Browning Reaction
Reducing Sugars and ?-amino acids
N-glycosylamine or N-fructosylamine
1-Amino-1-deoxy-2-ketose (Amadori intermediate)
Reductones and dehydroreductones
Strecker degradation
Amino Acids
Retroaldol condensation
H2S NH3
Furans Thiophenes Pyrroles
(Methional, NH3 H2S)
Hydroxyacetone Acetoin Acetylaldehyde
Glyoxal Pyruvaldehyde Glycerolaldehyde
Heterocyclizaion
Pyrazines, Pyridines,
Thiazoles, Pyrroles Oxazoles
91
Antioxidants from Maillard Browning
C
H
3
C
O
Nitrogeneous compounds
C
O
H
C
O
H
C
H
O
H
C
H
O
H
C
H
S
H
C
H
C
H
O
H
3
2
2
Ethyl thiol
Reductone
92
Polarity of Antioxidants

• Polar antioxidants are more active in bulk oil
• systems
• Hydrophobic antioxidants that are located on
• the interface of lipid/water can protect lipid
• better than hydrophilic antioxidants

93
Effects of Antioxidant Polarity in Food Systems
Oil
Water
Air
Water
Oil
Oil
Hydrophobic antioxidant
Hydrophilic antioxidant
94
Factors Affecting Partitioning Properties of
Antioxidants

• The chemical structure and polarity
• The types of lipid substrate
• The presence of surfactants
• The composition of the phases

95
Antioxidant Measuring Methods
96
Factors Affecting the Antioxidant Activity

• Substrates
• Conditions
• Analyses
• Concentrations
• Calculations

97
Substrates

• Substrates relevant to food systems including
• triacylglycerls and phospholipids
• Various bulk oil and emulsion system

98
Conditions

• Test under various oxidation conditions
• Different temperatures
• Metal catalysts
• Simulated real food systems

99
Analyses

• Initial products
• Peroxide value or conjugated dienes
• Secondary decomposition products
• Carbonyls or volatile compounds

100
Concentrations

• Compare antioxidants at the same molar
• concentration of active components using
• structurally related reference compounds.
• Consider the concentration ratio of
• antioxidants/substrates.

101
Calculations

• Quantify on the basis of
• Induction period increase percentage
• Inhibition percentage of peroxide value
• compared to the control sample
• Reduction percentage of volatile compounds

102
Consideration of Antioxidant Selection
103
Ideal Antioxidants

• No harmful physiological effects
• No objectionable flavor, odor, or color
• Effective in low concentration
• Fat-soluble
• Carry-through effect
• Readily-available
• Economical
• Not absorbable by the body

 
104
Possible Future Antioxidants
Antioxidant attached to packaging material
105
We are the world
106
(No Transcript)
107
Mechanism of Lipoxygenase in Linolenic Acid
H
H
H
H
H
H
cis
cis
cis
H
C
C
C
C
C
C
H
C
C
CH
H
(CH
)
(
C
H
)
C
O
O
H
2
4
3
.
2
6
H
- H
H
H
H
H
H
cis
H
cis
cis
H
C
C
C
C
C
C
H
C
.
C
CH
(CH
)
H
(
C
H
)
3
2
4
C
O
O
H
2
6
H
H
H
H
cis
cis
H
trans
H
C
C
C
C
H
C
C
C
H
(
C
H
)
.
C
O
O
H
(CH
)
CH
C
2
4
3
2
6
H
3

O
2
H
H
H
H
H
cis
cis
H
H
C
trans
C
C
C
C
C
C
H
(
C
H
)
C
O
O
H
2
6
CH
(CH
)
C
3
H
2
4
O
O
H
108
Formation of ?- Tocopherylquinone
C
H
C
H
3
3
?
O
O
C
H
C
H
3
3
ROO-

H
C
ROO ?
H
C
O
C
H
C
H
3
O
3
16
33
16
33
C
H
C
H
3
3
H2O
C
H
O
H
3
C
H
C
H
3
16
33
O
O
C
H
C
H
3
3
H
C
C
H
O
3
H
C
16
33
O
3
O
H
C
H
3
C
H
3
?-Tocopherylquinone
109
Antioxidant Effectiveness of Tocopherols
Hydrogen donating ability ? gt ? gt ? gt ? -
Tocopherol
110
Physical Quenching Mechanism of ?- Carotene on
Singlet Oxygen
1O2 1?-Carotene 3O2 3?-Carotene
3?-Carotene
1?-Carotene
Energy Transfer
Radiationless Transfer
111
Singlet Oxygen Quenching of Tocopherols
1O2 1Tocopherol 3O2 3Tocopherol
3Tocopherol 1Tocopherol
112
Reaction Rate of Ascorbic Acid with Singlet Oxygen
Reaction rate (M-1sec-1) 3.08 ? 108 at pH
4.0 1.86 ? 108 at pH 5.6 1.19 ? 108 at pH 7.0
113
Phospholipids
O
O
C
H
O
C
R
O
2
1
C
H
O
C
R
O
2
1
C
H
O
C
R
O
2
C
H
O
C
R
O
2
-
C
H
O
P
O
C
H
C
H
N
H
2
2
2
2
C
H
O
P
O
-
2
-
O
O
Phosphatidyl ethanolamine
Phosphatic acid
114
Reaction between Metal and Hydroperoxide

• Copper is 50 faster than ferrous in decomposing
  hydrogen peroxide
• Ferrous is 100 faster than ferric iron in
  decomposing hydrogen peroxide
• Ferrous is 1010 times more soluble than ferric
  iron

115
Amino Acid, Peptide and Protein

• Glycine, methionine, and lysine in emulsion
• system- antioxidant activity at low
  concentration
• and high pH.
• Carnosine inhibits the prooxidant activities of
  
• hemoglobin, lipoxygenase, iron, peroxyl, and
• hydroxyl radical.
• Ferritin and tranferritin proteins bind iron

116
Tocotrienols
R
1
H
O
C
H
C
H
C
H
C
H
3
3
3
3
R
O
2
R
3
Trivial Name Chemical Name R1 R2 R3 ?-Tocotrieno
l 5,7,8-Trimethyltocotrienol CH3 CH3 CH3 ?-Tocotr
ienol 5,8-Dimethyltocotrienol CH3 H CH3 ?-Tocotri
enol 7,8-Dimethyltocotrienol H CH3 CH3 ?-Tocotrie
nol 8-Methyltocotrienol H H CH3
117
Multifunctional Antioxidants

• Tocopherol
• Ascorbic acid

118
Long-Term Safety of Antioxidants
 

• Pathological effect
• Carcinogenic potential
• Interactions with enzymes
• Effects of reproduction
• The exact nature of the metabolism rate in man

119

• Lee, Shin. O. 011-82-31-913-7094 (H), 11-
  9496-7094
• Hong, Soon. J. 011-652-4576, 063-290-1462
• Chun, H. K. 031-299-0550, 02-2051-4050,
  016-339-0564(RDA)
• Kim, H. R (RDA) 02-503-2186, 031-299-0581,
  016-303-2186
• Chung, Young. J. 016-405-1023, 042-483-2369
• Min, M. S. 031-265-6786, Min, B. T. 43-221-9065,
  930-6149 (Pil)
• Kwon, Eun. S. 42-869-4516, Ha, Y. L.
  016-587-5471, 55-751-5471
• Yeo, W, K, 19-248-6408, 031-330-6007,
• Choi, Hyang, S, 018-315-0377,
• Kwon, Oh, N or Chugn Seong K. 011-313-6330,
  2-970-6330())
• Kim, H, Sook 431-261-2692, 02 6419-9842
• Yoon, Suk. H 02-6245-4958,
• Kim, J. goon011-459-2003, 02-549-2003,
  02-3408-3219, 3318,.734-827-2425(Sunghee)
  510-332-2262-Moon
• Martin 293-8039, Korea travel, 1-800-621-5131,
  Lotte, 422-4152, Yoon Beauty, 262-8999
• Lee, S00n. Y. 041-486-5427, Jang K. Ho, Moon Sil,
  Da Yeon, Seo Young, 205-402-9551
• Min, Stephen 547-5824, Kemp, 846-2066, Choe, E.
  O, 82-32-227-4701
• Kang, J. wha 011-82-11-707-6351,
  011-82-2-363-6351,
• Jung, M 82-63-904-1635 (H), 018-396-1635
• Kim, Gur W.33-250-8647 , 011-9466-8647