Q2. What is the chemical that reduces the amount of free radicals?
Glutathione reductase reducesglutathione (antioxidant) from its oxidized to its reduced form, thus recycling it tocontinue neutralizing more free radicals.
Q3. What is the studied group of hydroxybenzoic acids?
One of the most studied and promising compounds in the hydroxybenzoic group is gallic acid which isalso the precursor of many tannins, while cinnamic acid is the precursor of all the hydroxycinnamic acids.
Q4. What is the role of vitamin E in scavenging the superoxide radical?
Ascorbic acid is effective in scavenging the superoxide radical anion, hydrogen peroxide, hydroxyl radical, singlet oxygen and reactive nitrogen oxide (Barros et al., 2011).
Q5. What is the mechanism of reaction between hydrogen peroxide and iron catalyst?
If hydrogen peroxide reacts with an iron catalyst like Fe2+, the Fenton reaction can take place (Fe2+ + H2O2 → Fe3+ + OH. + OH-) forming the hydroxyl radical HO· (Flora, 2009).
Q6. What are the new trends in antioxidant treatments?
The new trends in antioxidant treatments include compounds that behave like the enzyme SOD in order to alleviate acute and chronic pain related to inflammation and reperfusion.
Q7. What is the role of vitamin E in the regeneration of lipids?
Vitamin E is the only major lipid-soluble, chain breaking antioxidant found in plasma, red cells and tissues, allowing it to protect the integrity of lipid structures, mainly membranes (Burton and Traber, 1990).
Q8. What are the limitations of the research around antioxidants?
Another limitation regarding antioxidants research are cell cultures, which are altered with time, causing the antioxidants tested in vitro to often react with the medium or be neutralized very quickly; thus leading to erroneous results, that are usually overlooked by peer-review.
Q9. How do you get the absorption of flavonoids through the gut?
In order to yield satisfactory absorption through the gut they have to be hydrolyzed to anthocyanin aglycones or phenolic acids (Liang et al., 2012).
Q10. What is the mechanism of the reaction between thiols and hydrogen peroxide?
RSS derive, under oxidative conditions, from thiols to form a disulfide that with further oxidation can result in either disulfide-S-monoxide or disulfide-S-dioxide as an intermediate molecule.
Q11. What is the common chemical antioxidant?
Vitamin C is considered a potent antioxidant and intervenes in many physiological reactions, but it can also become a prooxidant.
Q12. What are the external factors that help to promote the production of free radicals?
External factors that help to promote the production of free radicals are smoking, environmental pollutants, radiation, drugs, pesticides, industrial solvents and ozone.
Q13. What is the mechanism of oxidative modification of proteins?
Regarding proteins, there are three distinct ways they can be oxidatively modified: 1) oxidative modification of a specific amino acid, 2) free radical-mediated peptide cleavage and 3) formation of protein cross-linkage due to reaction with lipid peroxidation products (Lobo et al., 2010).
Q14. What is the promising research area?
Another promising research area are genetics, which aim to breed genetically modified plants that can produce higher quantities of specific compounds, yielding higher quantities of antioxidants (Devasagayam et al., 2004).
Q15. How many times does a cell get targeted by the hydroxyl radical?
It is estimated that every day a human cell is targeted by the hydroxyl radical and other such species and average of 105 times inducing oxidative stress (Valko et al., 2004).
Q16. Why does the controversy around dietary antioxidants depend on different factors?
The controversy around dietary antioxidants is because the capacity to display antioxidant and prooxidant behaviour depends on various factors.
Q17. What is the main reason why the researchers concluded that flavonoids are not a direct antioxidant?
Lotito and Frei (2006), after reviewing the published research in flavonoid metabolism, related the high antioxidant activity of blood plasma with the intake of flavonoid-rich food and concluded that flavonoids, due to being highly metabolized, may not contribute themselves to this increase, but rather help increase uric acid levels, which could be considered an indirect antioxidant activity.
Q18. What is the effect of a free radical on linoleic acid?
When it reacts with a free radical it becomes a radical itself, and if there is not enough ascorbicacid for its regeneration it will remain in this highly reactive state and promote the autoxidation of linoleic acid (Cillard et al., 1980).
Q19. What is the average absorbance of the conjugated diene?
The absorbance of the conjugated diene is around 234 nm which is also the normal absorbance wavelength of biological and natural compounds, making this the major drawback of this assay (Moon and Shibamoto, 2009).
Q20. What is the common assay used to determine the antioxidant capacity of a compound?
This colorimetric assay uses the DPPH radical, which changes from purple to yellow in the presence of antioxidants, and is widely used as a preliminary study (Moon and Shibamoto, 2009).