Transcript Antioxidant Synergy in foods

Dietary Antioxidant Synergy in foods
Nooshin Moradi
Food Chemistry 605
Antioxidant Activity
 Principle of antioxidant activity: based on the availability of
electrons to neutralize free radicals.
 Decrease the oxidative damage directly or indirectly
 In food application: lipid oxidation and prolong shelf life.
Antioxidant Synergy
 Mixture of two or more antioxidant including:
 Purified compounds
 Crude extracts
 Cooperative action: greater AOX effect than the sum of
individuals
 Regeneration Hypothesis
AOX Capacity in vitro
 Expressed by the terms such as ability, activity, capacity,
efficacy, parameter, potential, power, and reactivity.
 “Antioxidant Capacity” often means different things at
different occasions and to different people:
 Capacity of antioxidant compound for scavenging free
radicals
 Capacity of “antioxidation”
Methods for determination of AOX
capacity (AOC)
 2, 2-diphenyl-1-picrylhydrazyl (DPPH·)
 2, 2-azinobis (3-ethyl-benzothiazoline-6-sulphonic acid)
(ABTS·)
 Thiobarbituric acid reactive substances (TBARS)
 Ferric reducing ability of plasma (FRAP)
 Oxygen radical absorbance capacity (ORAC)
 Simplicity, instrumentation required, biological relevance,
mechanisms, endpoint, quantitation method, and potential
for both lipophilic and hydrophilic
AOX synergy in chemical and food
models
 Lipid peroxidation was effectively inhibited by the
combination of ascorbic acid and a-tocopherol
 Flavonols quercetin and quercetin-3-glucoside trigger a
noticeable increase in antioxidant activity when mixed in
solution with another flavonoid
 Antimicrobial effects of phenolic compounds against
Staphylococcus aureus (binary combination of BHA and
gallic acid)
AOX synergy in tissue culture and
clinical models
 Type of cells and type of antioxidant: different synergistic
effect in Human liver HepG2 cells, HT29 cancerous cells,
and rat H9c2 cells using raspberry and plant extract
 Rat and human study display some synergistic effect.
However, no optimal model has been yet established to
predict the AOX synergy of in vivo.
Synergistic or Antagonistic?
 Flavonoid interactions trigger antagonistic and synergistic effects
 Strong antagonistic reaction when quercetin-3-glucoside was
paired with five different anthocyanins (resulted in a considerable
loss of antioxidant activity)
 Antagonistic interaction when myricetin was paired with quercetin,
in a ratio 1:1. (The activity significantly lower than the sum of the
individual values)
 Antagonistic effect: BHA
Staphylococcus aureus
and carvacrol
or thymol
against
 Some antioxidants in combination act in a regenerating manner,
with either the stronger regenerating the weaker (antagonistic
effect) or the weaker regenerating the stronger (synergistic effect)
AOX potency of a compound
 Structural features:
 Ortho-dihydroxy structure in the B-ring
 3- and 5-OH
 Nature of the radical and its specific reaction mechanism
Factors affecting prediction of AOX
synergy in chemical models
 Analytical methods (consistency and standardization)
 Experimental condition (Concentration and volume ratio
of the individual AOX, AOX composition, solvent, test
medium, and solubility)
 Great variability in chemical tests and hardly relevant to
biological systems
Factors affecting AOX capacity in
vivo
 Bioavailability
 Biotransformation: Enzymatic conjugation
 Food matrices: bioavailability of anthocyanins varies
markedly depending on food matrices
 Partial pressures of oxygen: good radical-trapping
antioxidant behavior of beta-carotene (found in most
tissues under physiological conditions)
AOX synergy in chemical, biological,
and food systems
 Controversial and confusing on the nature and properties
of AOX mixtures because of their complexity found in
vivo and their different distribution patterns in human
tissues and cells.
 No simple relationship has been recognized to transfer
chemical models and food systems to in vivo situation
Capacity and efficacy of AOX in vivo
 Capacity and efficacy of antioxidants in vivo :
 Assessing the effect of antioxidant compounds and
materials on the level of oxidation in biological fluids and
tissues
 Reliable biomarkers: oxidation products of lipids, DNA,
strand breaks of DNA
References
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