It is well known that phenolic compounds are mainly responsible for antioxidant activities and total antioxidant activity is a integrated parameter of antioxidants present in a complex. A correlation between these two activities could help in identifying the contributing factors for both the activities.
Hello. The relationship is not obvious, as depends on the sample. The pool of the phenolic compounds can be low, but due to the high content of e.g. ascorbate the total antioxidant status can be very high. The antioxidant properties also differ amongst the phenols.
The antioxidant activity can be attributed to plethora of substrates present in the matrix under investigation. In order to get clear picture, it is recommended that the compound of interest should be isolated/purified. This will give a better estimation and correlation of antioxidant activity with compound of interest under investigation.
I agree with other Renata (above), that the relationship is not clear. The total phenolics can be an indicator of antioxidant activity, but you can be sure, mailnly of types of phenolics.
Besides this, if you are looking for biological antixidants, they can be better or less absorved in the gut, and it is considereded too.
good look
Dear Aditya:
Antioxidant action is a chemical or molecular property of a compound. Total antioxidant activity is not simply reflective of total phenolic substances in a complex mixture unless the mixture preponderantly contains polyhydroxylated flavonoid moieties. Total antioxidant activity could be ascribed to a number of molecules possessing antioxidant property, for instance ascorbate, GSH, etc. Ascorbic acid, with its vicinal hydroxyl groups in the sugar alcohol ring structure form, is similar to a catechol ((catechol possesses two vicinal phenolic hydroxyls) form, and has potent radical scavenging activity. Many flavonoid structures contain polyhydroxylated groups, which contribute to their in vitro antioxidant activity. However, flavonoid glycoside structures are most common in nature; the exceptions are catechins and (condensed) proanthocyanidins (including dimers, tetramers and galloyl proanthocyanidins). A procyanidin dimer has 10 hydroxyl groups. Most studies that evaluate the in vitro antioxidant function of flavonoids use the parent forms of the flavonoids, which are not most common in plants. However, free flavonoids such catechin dimers, proanthocyanidins (including) anthocyanidins (which are free, non-glycosylated entities), occurring in complex plant material can have superior antioxidant activity.
Whether polyphenolic (phenylpropanoids with cinnamoyl linkages) compounds are mainly responsible for observed in vitro antioxidant activities in a mixture depends on the type of food or food matrix, .i.e., grape and cocoa extracts, grape or berry juice concentrates/ extracts, wine extracts (including dealcolized), citrus extracts, etc.
The phenolics comprise flavonoids, phenolic acids, simple phenols (such as pyrogallol, occurring freely and not as conjugates), stilbenes, coumarins, flavonoids, isoflavonoids, catechins, condensed tannins (known now as proanthocyanidins), hydrolyzable tannins (gallotannins, derivatives of gallic acid, and ellagitannins, derived from gallotannins via oxidative coupling), lignans, and so on. The levels of these constituents widely fluctuate in plants and plant parts during different seasons. The potential and presumptive antioxidant capacity of each of these components depends on the kind of test system employed to measure oxidant (including free radical) generation. In a particular scenario, free (not glycosides, conjugates of glucose/sugar moieties) phenolic acids may occur in increased quantities in plant parts such as leaves; concurrently the levels of free flavonoids could be lower. For instance, flavonoids occurring as diglycosides (para-coumaroyl glycosides) could have lower pharmacological activity. Several plant flavonoids (for instance, the dietary flavonoid, quercetin, belonging to the subclass, flavonols) are hydrogen donating, chain breaking antioxidants in vitro, in addition to their activities as reducing and metal binding agents. As answered previously, one may also note that the potential antioxidant activity of plant extracts could also be ascribed, in part, to the action of L-ascorbic acid (which is not a polyphenol), and diterpenes (formed by condensation of four isoprene units, which contain 20 carbon atoms).
The term “phenolics” perhaps needs to be simply modified and re-classified as flavonoids and non-flavonoids. It would turn out that about 8,150 individual discrete flavonoid molecules appear to have been recorded as of the year 2009. The total number of non-flavonoid polyphenols may be fewer than this. One would presume that this spectacular and mind boggling number (flavonoids) - like an army, a legion - may only be a fraction of the total number present in nature (tip of the icebeg). Prof. Edwin Haslam applied the term “polyphenols” to describe condensed molecules known as proanthocyanidins, which bore another name, vegetable tannins. The word “tannin” felt arcane, and subsequently, the term, polyphenols, came into vogue.
The term phenolics encompass the following. 1) SIMPLE PHENOLS --> A) SINGLE-RING AROMATIC compounds with one or more hydroxyl groups (-OH) such as salicylic acid, catechol, pyrogallol. B) STILBENES and PHENOLIC ACIDS with phenylpropanoid side chains (cinnamoyl esters - caffeic acid, chlorogenic acid, etc., dimers of esters such as curcumin). 2) PROGRESSIVELY COMPLEX PHENOLICS with additional aromatic/heterocyclic ring structures --> lignans/diphenols classified as phytoestrogens; coumarins (containing furans); flavonoids (aglycones) and anthocyanidins; isoflavonoids; isoflavonoid based pterocarpans (phytoalexins); proanthocyanidins (previously known as condensed tannins ); hydrolyzable tannins (gallotannins, derivatives of gallic acid and ellagitannins, derived from gallotannins via oxidative coupling), and so on. Flavonoid glycosides (conjugation with glucose, galactose, rhamnose, etc. -- O and C-glycosides) are generally found at positions (carbons) 3,5,7,8, etc. Other substitutions are acids, prenylation, farnesylation, acylation, methylation, etc.
Total phenolic activity represent chemical reaction based binding of a phenolic compound that contains free oxygen not a free radical, but total antioxidant activity displays presence and conversion of free radicals present in a biological sample. One is merely a pure chemical while antioxidant activity report biological changes due to oxidation of substances inside animal body.
The question, here, perhaps needs to be rephrased as "total phenolic content" because that is what one aims to measure. Total phenolic content represents all compounds in the sample possessing free (unsubstituted) hydroxyl (-OH) groups attached to a benzene ring. The estimation of total phenolic substances utilizes a number of methods. Folin–Ciocalteu (F–C) reagent, one of the reagents employed to measure total phenol containing substances in a sample, is not specific for compounds with phenolic hydroxyl groups; ascorbic acid reacts with Folin- Phenol (F–C) reagent, and interferes with the measurement.
Antioxidant action is a chemical property of an agent. A substance with antioxidant potential is capable of preventing, impairing or retarding the oxidation of other molecules. Assessment of total antioxidant activity generally employs in vitro chemical assays that utilize radical scavenging to measure reducing or hydrogen donating activity of nonenzymic antioxidants. L-Ascorbic acid as well as flavonoids are reducing agents. Test systems normally contain labile transition metals. Flavonoids are chain breaking antioxidants in vitro, in addition to their activities as metal binding agents; they complex (or chelate in the case of divalent metals) metal ions. Metal chelation potentially prevents the reaction with reactive oxygen species or maintains the metal in a redox state, resulting in its inability to reduce molecular oxygen.
Concerning total phenolic content of a sample mixture the levels of flavonoids and other plant phenolics, such as phenolic acids, stilbenes, lignans, etc. widely fluctuate during different stages of the life cycle of a plant; generally, most phenolic compounds are found at the flowering stage.
The antioxidant activity of four species of the Malvaceae family (Sidastrum micranthum (A. St.-Hil.) Fryxell, Wissadula periplocifolia (L.) C. Presl, Sida rhombifolia (L.) E. H. L and Herissantia crispa L. (Brizicky)) were studied using the total phenolic content, DPPH radical scavenging activity and Trolox equivalent antioxidant capacity (TEAC) assays. The antioxidant activity of the crude extract, phases and two isolated flavonoids, kaempferol 3,7-di-O-α-L-rhamnopyranoside (lespedin) and kaempferol 3-O-β-D-(6''-E-p-coumaroil) glucopyranoside (tiliroside) was determined. The results showed that there is a strong correlation between total polyphenol contents and antioxidant activity of the crude extract of Sidastrum micranthum and Wissadula periplocifolia; however, this was not observed between Sida rhombifolia and Herissantia crispa.
Further studies are needed to identify which phenolic compounds are responsible for the antioxidant activity of the species, and assess the way in which the phenolic substances contribute to this activity. Additional in vivo antioxidant assays are needed to confirm the potential use of these species in disease treatment.
The explanation about phenolic compounds by Chithan C Kandaswami ·is excellent, I agree. Not only the relationship between phenolics and antioxidant activity but also with anti-inflammation, anti-glycation as well.See more references in:http://www.ncbi.nlm.nih.gov/pubmed/22158590.
and http://www.ncbi.nlm.nih.gov/pubmed/19275712
generally we find a positive co-relation between phenolics and antioxidant activity. however, there can be a drift sometimes. this is because of the type of phenolics and amount of individual phenolic compound present in the sample.
I devote to polyphenols and their relation to antioxidant activity. I can claim that we measure a strong positive correlation in the samples of lesser known fruit species
I agree with the comments of Chithan Kandaswami. In plants, generally, when levels of total phenolics are higher, we get high antioxidant activity, but it depend upon the stress applied. Levels of flavonoids and other plant phenolics may fluctuate during different developmental stages of plants under the applied stress.
recent studyes has shown an association between the total phenolic content and the antioxidant capacity. antioxidants are mainly phenolic compounds, such as flavonoids.The protective effects of polyphenols and flavonoids in biological systems are attributed to their antioxidant capabilities, electron transfer, reducing hydrogen peroxide, activation of antioxidant enzymes, reducing Alpha-Tocopherol radicals and quenching superoxide and singlet oxygen.
Flavonoids are known to have pleiotropic actions. Many of their pharmacologic activities (in vitro, at pharmacological concentrations) in biological systems may also be owing to enzyme modulation, and modulatory actions on immune and infalmmatory cell functions, and cell surface signal transduction.
The Effects of Plant Flavonoids on Mammalian Cells:Implications for Inflammation, Heart Disease, and Cancer Pharmacol Rev, 2000 52:673-751.
http://pharmrev.aspetjournals.org/content/52/4/673.full.pdf+html
In in vitro studies, the reduction of radicals depends on the redox potential of the molecule in question. For instance, ascorbate can protect against the oxidation of quercetin, a pentahydroxy flavonoid known as flavonol; quercetin, in turn, can protect alpha-tocopherol. Ascorbate can also protect quercetin although not owing to its redox potential (of ascorbate). In some instances, one would not be able to ascertain if a flavonoid is functioning by expressing antioxidant (radical scavenging) activity in biological systems in vitro or simply inhibiting an enzyme (such as superoxide dismutatse).
Dear Aditya,
I work with phenolic compounds and antioxidant activity in fruits and their products. The classical analysis of total phenols is made by Folin and determines all phenols, but can react with some proteins which must be eliminated by precipitation prior to analysis. Other compounds such as ascorbic acid and SO2 can react with the reactive Folin and generate a false positive result. The best method to quantitate the phenolic compounds is by chromatography (HPLC or UPLC with or without expectro mass). The methods most commonly used antioxidant activity as FRAP and DPPH antioxidant assess the potential of these compounds, which consists of the capacity to release hydroxyls which neutralize free radicals. In fruits you can find classes and their compounds with low and / or high antioxidant activity. Normally the correlation between phenolics and antioxidant activity is high, it is interesting to analyze each class or compound and relate to the antioxidant activity.
PHENOLS and total phenols as most of the above mention ,but the antioxidant involved besides phenols ,some metals and organic acid or bioorganic as ascorbic acid ,The most strong metals as vanadium, selenium besides the charge molecules has -oh -hydroxly can play role in oxidation or reduction of compounds esp.in vivo.
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