The Chemical Reactivity of Anthocyanins and Its Consequences in Food Science and Nutrition

Abstract

Owing to their specific pyrylium nucleus (C-ring), anthocyanins express a much richer chemical reactivity than the other flavonoid classes. For instance, anthocyanins are weak diacids, hard and soft electrophiles, nucleophiles, prone to developing π-stacking interactions, and bind hard metal ions. They also display the usual chemical properties of polyphenols, such as electron donation and affinity for proteins. In this review, these properties are revisited through a variety of examples and discussed in relation to their consequences in food and in nutrition with an emphasis on the transformations occurring upon storage or thermal treatment and on the catabolism of anthocyanins in humans, which is of critical importance for interpreting their effects on health.

Expanding the Chemical Palette of Industrial Microbes: Metabolic Engineering for Type III PKS‐Derived Polyketides

“…Flavonoids are an extremely broad class of plant metabolites that protect plants from pathogens, UV, and oxidative damage . Several chemicals in this group show potential as antioxidant protective agents and possess antitumor, antidiabetic, and neuroprotective activity . Flavonoid molecules are produced from a phenylpropanoid CoA ester by the type III PKS, chalcone synthase (CHS) that catalyzes the extension into a chalcone.…”

“…[83,84] Several chemicals in this group show potential as antioxidant protective agents and possess antitumor, antidiabetic, and neuroprotective activity. [85][86][87] Flavonoid molecules are produced from a phenylpropanoid CoA ester by the type III PKS, chalcone synthase (CHS) that catalyzes the extension into a chalcone. This starting flavonoid scaffold is then isomerized to produce a flavanone by chalcone isomerase (CHI) (Figure 4a).…”

Anthocyanin in the Vacuole of Red Onion Epidermal Cells Quenches Other Fluorescent Molecules

“…It was concluded, therefore, that vacuolar anthocyanin can statically quench other fluorescent molecules in vivo, an effect previously demonstrated for anthocyanin in vitro.2 of 15 pH-dependant, which means that anthocyanin colour, and the colour of the plant, will depend upon vacuolar pH. Anthocyanin colour may also vary because anthocyanins can interact with themselves, stacking to form super-molecular structures, and can interact with other flavonoid pigments, stabilising the coloured forms at acidic pHs, and also interact with metal ions [1][2][3][4].Like many flavonoids, anthocyanins can be weakly autofluorescent with in vitro excitation and emission peaks in the UV [4,5]. However, in vivo excitation of anthocyanins in both Arabidopsis thaliana and onion (Allium cepa) results in red fluorescence, and has allowed for direct visualisations of vacuole structure and dynamics [6][7][8].The flavonoid biosynthetic pathway, a complex series of reactions in which coumaroyl-CoA is sequentially modified to form various end-products, results in the formation of anthocyanins [9].…”

“…2 of 15 pH-dependant, which means that anthocyanin colour, and the colour of the plant, will depend upon vacuolar pH. Anthocyanin colour may also vary because anthocyanins can interact with themselves, stacking to form super-molecular structures, and can interact with other flavonoid pigments, stabilising the coloured forms at acidic pHs, and also interact with metal ions [1][2][3][4].…”

“…Like many flavonoids, anthocyanins can be weakly autofluorescent with in vitro excitation and emission peaks in the UV [4,5]. However, in vivo excitation of anthocyanins in both Arabidopsis thaliana and onion (Allium cepa) results in red fluorescence, and has allowed for direct visualisations of vacuole structure and dynamics [6][7][8].…”