non-enzymatically acting antioxidant molecules, of which decreased glutathione (GSH), ubiquinol, dehydrolipoic acid, melatonin, ferritin, Antioxidants 2022, 11, 133. doi.org/10.3390/antiox11010133 mdpi/journal/antioxidants caeruloplasmin, and metallothioneins are endogenously synthesized [8], when -tocopherol, ascorbic acid, carotenoids and phenolics are acquired by way of dietary sources [9].with regard to jurisdictional claims inAntioxidants 2022, 11,two ofIn addition to this cooperative array of enzyme-based antioxidant defense mechanisms, cells contain numerous non-enzymatically acting antioxidant molecules, of which lowered glutathione (GSH), ubiquinol, dehydrolipoic acid, melatonin, ferritin, caeruloplasmin, and metallothioneins are endogenously synthesized [8], though -tocopherol, ascorbic acid, carotenoids and phenolics are acquired by means of dietary sources [9]. Amongst the latter molecules, academia and industry have paid an excellent deal of consideration to phenolics, especially flavonoids, as a result of their comparatively greater antioxidant capacity and ubiquitous presence in edible plants [10,11]. 2. Flavonoids as Antioxidants Flavonoids have attracted the focus of biomedical researchers because of their possible to induce an array of health-promoting biological actions [125]. Key help for the possible well being positive aspects of these compounds initially emerged from epidemiologic research performed inside the 1990s. At that point, inverse correlations among the intake of flavonoid-rich foods and the relative threat of building particular chronic noncommunicable ailments (NCDs) had been established [161]. Over the last two decades, on the other hand, the conclusions arising from these population-based research have gained assistance via numerous animal research, in vitro cell mechanistic investigations and human intervention studies [19,227]. Comprehensive testimonials on the overall health effects of dietary flavonoids have appeared in recent years [15,281]. Close to eight thousand flavonoids have already been described to date within the plant kingdom [11]. The systematic study of these of dietary origin has led towards the improvement of various reports and/or databases that inform on their contents in foods and dietary level of consumption, and their biotransformation and bioavailability [325]. From a chemical point of view, the term flavonoid comprises all these molecules whose structural backbone (a flavan nucleus, C6 3 6, Figure 1) consists of two benzene rings (A and B) that are linked via 3 carbon atoms that type a pyran heterocyclic ring (C). This structure allows multiple patterns and substitutions that give rise to numerous subclasses of flavonoids, amongst which flavonols, flavones, flavanones, FGFR manufacturer flavanols and anthocyanidins could be distinguished. Such categorization is determined by whether or not the flavan nucleus JNK1 drug includes a hydroxyl moiety in C3 (i.e., flavonols, flavanols and anthocyanidins), a keto group in C4 (i.e., flavonol, of 29 flavones Antioxidants 2022, 11, x FOR PEER Critique 3 and flavanones), a double bond in C2 3 (i.e., flavonols and flavones), a double bond in O1 2 and a further in C3 four (anthocyanidins).Figure 1. Flavan nucleus, 2-phenyl-3,4-dihydro-2H-1-benzopyran skeleton, prevalent to all flavoFigure 1. Flavan nucleus, 2-phenyl-3,4-dihydro-2H-1-benzopyran skeleton, prevalent to all flavonoids noids (C6 three six). (C6 3 six).In addition to flavonoids, you will discover isoflavonoids, primarily represented by the isoflavones, whose structure includes a double bond at C2 three in addition to a keto group at C4. Iso