New features of intramolecular copigmentation byacylated anthocyanins

Abstract

Three series of structurally related anthocyanins, extracted from the red–purpleflowers of Dendrobium Pramot, xLaeliocattleya cv. Mini Purple, Bletilla striata and Phalaenopsis all belonging to the Orchidaceae family and another series extracted from the pinkflowers of Senecio cruentus (Compositae) allowed the confirmation of the existence of strongintramolecular copigmentation effects. These interactions confer stability to the coloured formsof the molecules, in a wide range of slightly acidic to neutral aqueous media. Moreover, theexistence of structural relationships among the four series stressed the different influencesexerted by the diverse substituent groups. The existence of a malonylglucoside attached toposition 3 of all but three of the molecules put forward a new role for the malonyl residue, in thisparticular position.