Flavonoids, the Role and the Importance in Modern Investigations

The flavonoids are aromatic secondary plant metabolites, which belong to the class of plant polyphenolics. Structurally they are heterocyclic π-electron systems built upon a C6H5(A)-C3-C6H5(B) flavone skeleton in which oxygen is the heteroatom. A group of flavonoids is differentiated in several classes according to the degrees of oxidation and unsaturation of the heterocyclic C ring. Because of the remarkable array of biological and pharmacological activities, physiolological effects, complexity of the biosynthesis and metabolism, possible industrial applications and constantly rising commercial interest and relevance in the processes involved in nutrition, flavours, and aromas flavonoids, especially anthocyanins and flavones, are receiving renewed attention of many researchers during the last decade. A considerable number of plants which contain flavonoids are reported to exert a wide range of positive health attributes, antimutagenic, antibacterial, anti-inflammatory, antiallergic, antiviral, anti-thrombotic, and vasodilatory actions, mainly arising from their antioxidant ability. Anthocyanidins and their glycosylated forms, anthocyanins, as the most widely spread class of the flavonoids, are the most intensively colored substances responsible for the existence of the most red, blue and purple colours in flowers and fruits. Increasing public concern about the safety of synthetic food colorants influenced the greater prominence of these molecules. Anthocyanins have a very long history as a part of a human diet resulting in appreciation of good food quality, flavour identification and taste thresholds influencing food preference and acceptability. The fact that these molecules are one of the thirteen pigment classes, derived from natural sources, permitted in Europe emphasise the importance of their study.