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Polyphenols (/ ˌ p ɒ l i ˈ f iː n oʊ l,-n ɒ l /) are a large family of naturally occurring phenols. [1] They are abundant in plants and structurally diverse. [1] [2] [3] Polyphenols include phenolic acids, flavonoids, tannic acid, and ellagitannin, some of which have been used historically as dyes and for tanning garments.
The main source of polyphenols is dietary, since they are found in a wide array of phytochemical-bearing foods.For example, honey; most legumes; fruits such as apples, blackberries, blueberries, cantaloupe, pomegranate, cherries, cranberries, grapes, pears, plums, raspberries, aronia berries, and strawberries (berries in general have high polyphenol content [5]) and vegetables such as broccoli ...
The phenolic unit can be found dimerized or further polymerized, creating a new class of polyphenol. For example, ellagic acid is a dimer of gallic acid and forms the class of ellagitannins, or a catechin and a gallocatechin can combine to form the red compound theaflavin, a process that also results in the large class of brown thearubigins in tea.
The terms flavonoid and bioflavonoid have also been more loosely used to describe non-ketone polyhydroxy polyphenol compounds, which are more specifically termed flavanoids. The three cycles or heterocycles in the flavonoid backbone are generally called ring A, B, and C. [ 2 ] Ring A usually shows a phloroglucinol substitution pattern.
A bioactive compound is a compound that has an effect on a living organism, tissue or cell, usually demonstrated by basic research in vitro or in vivo in the laboratory. While dietary nutrients are essential to life, bioactive compounds have not been proved to be essential – as the body can function without them – or because their actions are obscured by nutrients fulfilling the function.
As part of their adaptation from marine life, terrestrial plants began producing non-marine antioxidants such as ascorbic acid (), polyphenols, and tocopherols.The evolution of angiosperm plants between 50 and 200 million years ago resulted in the development of many antioxidant pigments – particularly during the Jurassic period – as chemical defences against reactive oxygen species that ...
Others, such as some polyphenols and flavonoids, may be pro-oxidants in high ingested amounts. [23] Non-digestible dietary fibers from plant foods, often considered as a phytochemical, [24] are now generally regarded as a nutrient group having approved health claims for reducing the risk of some types of cancer [25] and coronary heart disease. [26]
The estimated daily intake of flavones is about 2 mg per day. [1] Following ingestion and metabolism, flavones, other polyphenols, and their metabolites are absorbed poorly in body organs and are rapidly excreted in the urine, indicating mechanisms influencing their presumed absence of metabolic roles in the body.