Flavonoids and Derived Anthocyanin Pigments in Plants—Structure, Distribution, Function, and Methods for Quantification and Characterization

Flavonoids represent a large class of phenolic specialized metabolites and play crucial roles in plant–environment interactions, including responses to biotic and abiotic factors. While the core flavonoid biosynthesis pathway is well known in several plant species, enzymes involved in modifying core flavonoid structures, furnishing them with distinct biological activities, continue to be identified. Anthocyanins, a specific type of flavonoid pigment, serve various functions, including attracting pollinators and seed-dispersing organisms when accumulated in flowers and seeds. Anthocyanins also accumulate in vegetative tissues of many plants, especially under unfavorable conditions. In this review, we present an overview of the diverse structures, various distributions, and multiple functions of flavonoids in plants.