December 29, 2023 Longchang Chemical

What are the six main categories of natural antioxidants?

Antioxidants act as hydrogen donors and are used to scavenge free radicals generated during the chain initiation phase, thus inhibiting or reducing the oxidation of fats and oils. Therefore, the most common and effective way to slow down the oxidation of fats and oils and to prolong the shelf life of fats and oils is to add antioxidants to fats and oils.

The safety of synthetic antioxidants has been questioned due to the many safety concerns, such as teratogenicity, carcinogenicity, and chronic diseases associated with overuse.

Natural antioxidants are extracted from plants and animals and are characterized by high safety, strong antioxidant capacity, no side effects, and anticorrosion and freshness preservation.

Natural antioxidants can be categorized according to their mechanisms: free radical absorbers, metal ion chelators, oxygen scavengers, single-linear oxygen quenchers, hydroperoxide decomposers, ultraviolet absorbers, and enzyme antioxidants. Common natural antioxidants are mainly divided into the following categories:

I. Flavonoids
Flavonoids are a class of compounds that exist in nature, with 2-phenylchromone structure of low molecular natural plant components, the human body can not be synthesized, need to be ingested from the outside world. Their molecules have a ketone carbonyl, the first position of the oxygen atom with alkaline, can form salts with strong acids, and its hydroxyl derivatives have yellow color, so it is also known as xanthophylls or flavonoids.

There are two types of antioxidant mechanisms of flavonoids:

1, chelating metal ions, can form chelates with metal ions, reduce the catalytic activity of metal ions, impede the occurrence of oxidation reactions, and can be a good way to remove reactive oxygen species (ROS) and reactive nitrogen species.

2, scavenging free radicals, providing hydrogen atoms to hydrogen peroxide radicals, generating stable hydroperoxides, and the phenolic hydroxyl group in the molecule reacts with oxygen radicals to form conjugated stable semiquinone radicals, interrupting the chain reaction of free radicals.

Examples of flavonoid natural antioxidants:

1, peanut shell extract, with antioxidant active component 3,4,5,7-tetrahydroxyflavone, is an auto-oxidizing free radical inhibitor, its antioxidant activity is equivalent to butylated hydroxytoluene (BHT), higher than tocopherol.

2, Licorice extract, containing licorice chalcone A, licorice chalcone B and licorice isoflavones, with strong scavenging of free radicals and inhibition of enzymatic oxidation.

3, Proanthocyanidins, the inhibition of lipid oxidation is significant, lecithin and vitamin E have a good effect on the potentiation of proanthocyanidins. In the inhibition of fat oxidase activity, proanthocyanidins and tea polyphenols have the same effect.

4, others, galangal extract in galangal, rutin in acacia rice, apigenin in oregano grass, and quercetin in jindiro belong to flavonoids, and their antioxidant capacity on fats and oils are equivalent to butylated hydroxytoluene (BHT) or higher than butylated hydroxytoluene (BHT).

Polyphenolic compounds is a group of plants in the chemical substances collectively, because of the phenolic group and named. Can be divided into 2 categories, one is a polyphenol monomer, including chlorogenic acid, ellagic acid, as well as a number of glycoside-containing composite polyphenol compounds; the other is a polyphenol monomer polymerization of oligomer or polymer, collectively referred to as tannin-like substances.

Examples of polyphenols natural antioxidants:

1, tea polyphenols, its antioxidant activity is butylated hydroxyanisole (BHA) 2.6 times, is 3.6 times the vitamin E. Since tea polyphenol is water-soluble, it needs to be modified into oil-soluble type to play a better role in fats and oils.

2, resveratrol, mainly from peanuts , grapes (red wine), thuja, mulberries and other plants, resveratrol is a polyphenol compound, known for its effective activation of longevity proteins – deacetylase (sirtuins). sirtuin is an important factor in slowing down cellular senescence and prolonging life by regulating a variety of cellular processes. the inhibition of cellular senescence by sirtuin primarily Sirtuin’s inhibition of cellular senescence is mainly mediated by delaying age-related telomere loss, maintaining genome integrity and promoting DNA damage repair.

Natural pigments
Natural pigments contain a large number of phenolic hydroxyl groups, so they have efficient hydroxyl radical and peroxyl radical scavenging ability, and also have strong reducing properties, can burst single-linear oxygen, is a very promising natural oil antioxidant, and its antioxidant capacity is vitamins (e.g., vitamin C, vitamin E) several times. Common natural pigments include beta-carotene, lycopene, astaxanthin, etc. The disadvantage of natural pigment-based antioxidants is that they are poorly water-soluble, not easy to mix colors, and easy to change color.

Some scholars have studied the antioxidant properties of astaxanthin and other five natural antioxidants in two edible oil systems, and found that the antioxidant effect in canola oil is astaxanthin> lycopene> vitamin C> vitamin E> β-carotene> lutein, and the antioxidant effect in soybean oil is astaxanthin> lutein>vitamin C≈ vitamin E≈ β-carotene> lycopene.

Fourth, vitamins and their derivatives
Vitamins are indispensable to human life activities of a nutrient, most of which can not be synthesized in the body, or synthesized in small amounts, need to be taken from food, of which vitamin C, vitamin E, coenzyme Q has a strong antioxidant function.

1, vitamin E, also known as tocopherol, is an important class of physiologically active substances, some researchers believe that its antioxidant function is not only embodied in the removal of free radicals, but also remove the formation of lipid peroxides of potential sources, inhibit the oxidation of polyunsaturated fatty acids in the membrane of tissues around the cellular particles and erythrocytes within the membrane, and can react with peroxides will be transformed into harmless to the cells of the material to maintain the integrity of cell membranes of the long-chain polyunsaturated fatty acids, thus maintaining the cell membrane. Unsaturated fatty acids in the cell membrane to maintain the integrity of its biological activity.

2, vitamin C, also known as ascorbic acid, soluble in water, slightly soluble in acetone, its antioxidant activity is mainly realized through the scavenging of free radicals, through the supply of electrons step by step into semi-dehydrovitamin C, in order to achieve the purpose of scavenging free radicals such as OH-, ROO-.

3、Coenzyme Q10 is a quinone compound, widely found in animals, plants, microorganisms and other cells, usually in very low content, in the body there are oxidized and reduced 2 forms of existence, and can be transformed into each other, but only the reduced form can play an antioxidant role, mainly in the scavenging of free radicals, stabilize the cell membrane and anti-apoptosis.

Antioxidant peptide
Antioxidant peptides mainly come from animal and plant proteins and their hydrolysis products.

1, soy peptide, soy protein by enzymatic hydrolysis of a certain molecular weight peptide, has a strong ability to inhibit free radicals, but also inhibit the activity of lipoxygenase, inhibit the pathway: ① complex enzyme active site Fe3 +; ② and the substrate to compete for the enzyme’s active site; ③ and enzyme molecules interact with the enzyme or change the enzyme’s spatial structure, thus reducing the enzyme’s activity.

2, glutathione, composed of glutamic acid, cysteine and glycine, referred to as GSH, the molecule has a reduced state of sulfhydryl-SH, so it has antioxidant properties. Antioxidant pathway: ① block free radicals; ② binding H₂O₂; ③ scavenging ester peroxides.

Six, active polysaccharide
Polysaccharide is a kind of natural polymer, usually consists of more than 10 monosaccharides connected by straight chain or branched chain glycosidic bonds, with molecular weight of tens of thousands to millions (sodium hyaluronate is also considered a kind of polysaccharide).

Studies have shown that ginseng polysaccharides and bamboo plum polysaccharides have better scavenging effect on -OH, blueberry polysaccharides have stronger scavenging effect on -OH and DPPH radicals, and ginger polysaccharides have better scavenging effect on DPPH- than on -OH.


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