How do phenols act as antioxidants?
Phenolics are able to act as antioxidants in a number of ways. The interaction of the hydroxyl groups of phenolics with the π-electrons of the benzene ring gives the molecules special properties, most notably the ability to generate free radicals where the radical is stabilized by delocalization.
What are the antioxidant mechanisms?
An antioxidant is a substance that at low concentrations delays or prevents oxidation of a substrate. Antioxidant compounds act through several chemical mechanisms: hydrogen atom transfer (HAT), single electron transfer (SET), and the ability to chelate transition metals.
What are phenolic antioxidants?
A phenolic compound is defined as an antioxidant when, present in low concentration relative to the substrate that will undergo oxidation, it delays, retards, or prevents autoxidation or free radical-mediated oxidation, the radical formed after scavenging being stable (Halliwell & Gutteridge, 2015).
How polyphenols work as antioxidants?
Polyphenols have been found to be strong antioxidants that can neutralize free radicals by donating an electron or hydrogen atom. The highly conjugated system and certain hydroxylation patterns such as the 3-hydroxy group in flavonols are considered important in the antioxidant activities.
Is phenol A stable antioxidant?
Phenolic compounds with bulky alkyl substituents near the hydroxyl group, such as BHA, BHT, TBHQ (Figure 9.1), are effective chain-breaking antioxidants because (a) they produce stable and relatively unreactive antioxidant radicals A·, by reactions (4) and (5), that are too unreactive to propagate the chain, and (b) …
Is phenolic compounds and antioxidant?
Phenolic compounds and flavonoids are known by their antioxidant properties and one of the most important sources for humans is the diet. These results suggest that these novel compounds may function to protect foods and medicines and to reduce oxidative stress in vivo.
What are the types of antioxidants?
Flavonoids, flavones, catechins, polyphenols, and phytoestrogens are all types of antioxidants and phytonutrients, and they are all found in plant-based foods….Examples of antioxidants that come from outside the body include:
- vitamin A.
- vitamin C.
- vitamin E.
- beta-carotene.
- lycopene.
- lutein.
- selenium.
- manganese.
Which of the following is a phenolic type antioxidant?
Why phenols are good antioxidants?
The antioxidant capabilities of phenols are strongly reduced by hydrogen-bond accepting solvents since the hydrogen-bonded molecules ArOH—S are virtually unreactive toward ROO* radicals. On the one hand, they act as hydrogen-bond accepting solvents and reduce the conventional rates of the ArOH + ROO* reaction.
What is the difference between polyphenol and antioxidant?
Antioxidants are molecules that protect our bodies from the damage caused by free radicals. Polyphenols are a type of antioxidant that is found in abundance in extra virgin olive oil. Many of the fruits and vegetables we consume contain a large number of compounds critical for life.
Are all polyphenols antioxidants?
Polyphenols are the most abundant antioxidants in the diet. Their total dietary intake could be as high as 1 g/d, which is much higher than that of all other classes of phytochemicals and known dietary antioxidants.
How are sterically hindered phenols used as antioxidants?
Some of the most widely used antioxidants are sterically hindered phenols. These compounds act as a primary antioxidants by converting peroxyl radicals to hydroperoxides. Thus, they inhibit autooxidation of organic polymers by reducing the amount of peroxyl radicals.
Which is the represenative of butylated hydroxytoluene?
Butylated hydroxytoluene (BHT) is only one among many sterically hindered phenols. Other represenatives include butylated hydroxyanisole (BHA), tertiary-butylhydroquinone (TBHQ) and gallates among many others which all undergo similar reactions.
Which is an example of a represenative phenol?
Butylated hydroxytoluene (BHT) is only one among many sterically hindered phenols. represenatives include butylated hydroxyanisole (BHA), tertiary-butylhydroquinone (TBHQ) and gallates among many others which all undergo similar reactions.