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Did the Anthocyanin Colour System had Ancestors? What Physical Chemistry can Tell us

Fernando Pina

Anthocyanins are the basis of the angiosperms colour, 3-deoxyanthocyanins and sphagnorubin play the same role in mosses and ferns and auronidins are responsible for the colour in liverworts. The separation of the ancestors of each of these lineages occurred in different periods of land plant evolution, therefore, our thesis is that chemical evolution of the colour systems accompanied plant evolution. The colour system of cyanidin-3-O-glucoside (kuromanin) as a representative compound of simpler anthocyanins was here fully characterized by stopped flow. This type of anthocyanins cannot confer significant colour to plants without intra or intermolecular interactions, complexation with metals or supramolecular structures as in Commelina communis. The anthocyanin’s colour system was compared with the one of 3-deoxyanthocyanins and riccionidin A the aglycone of auronidins. The three systems follow the same sequence of chemical reactions, but the respective thermodynamic and kinetics is dramatically different.