Flavonoidi

Flavonoidi are a diverse class of polyphenolic compounds produced by plants. They share a common C6-C3-C6 skeleton and occur as aglycones or glycosides, contributing to plant coloration, flavor, and defense. They are abundant in many edible plants and account for a large portion of dietary polyphenols.

They are subdivided into several major groups: flavones, flavonols (such as quercetin and kaempferol), flavanones (hesperetin, naringenin), flavanols or catechins (catechin, epicatechin), isoflavones (daidzein, genistein), and anthocyanidins (e.g., cyanidin) that form pigments as anthocyanins when glycosylated. Chalcones are sometimes included; each group differs in hydroxylation patterns and glycosylation.

Sources include fruits and vegetables (citrus fruits, onions, berries, apples), tea, cocoa, wine, and legumes. In plants, flavonoids serve as pigments, UV protectants, and defense compounds against pathogens and herbivores; they also participate in signaling with pollinators and symbionts.

Biosynthesis proceeds mainly via the phenylpropanoid pathway, with chalcone synthase as a key enzyme, followed by modifications such as hydroxylation, methylation, glycosylation and acylation. In humans, flavonoids are absorbed as glycosides or aglycones, often metabolized to glucuronides or sulfates and transformed by gut microbiota.

Health relevance: substantial interest exists regarding antioxidant, anti-inflammatory, cardiometabolic, and anticancer potential, but effects depend on bioavailability, dose, food matrix, and individual variation. Flavonoids can interact with drug-metabolizing enzymes and nutrient transporters, and should be consumed as part of a balanced diet rather than as high-dose supplements.