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 and carvacrol or thymol against Staphylococcus aureus  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

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