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Chemical investigation of blackcurrant seed residue from oil extraction revealed the presence of an array of polyphenols which were dominated by four anthocyanins consisting of the rutinosides and glucosides of delphinidin and cyanidin. Also isolated were the glucosides and rutinosides of myricetin and quercetin, kaempferol-3-glucoside, dihydroquercetin and aureusidin, as well as the phenolic acids 1-cinnamoyl- and 1-p-coumaroyl-β-d-glucosides. This is the first report of aureusidin and 1-cinnamoyl-β-d-glucoside as blackcurrant constituents. [Copyright &y& Elsevier]

Four new pyranoanthocyanins, namely pyranocyanin C and D and pyranodelphinin C and D, possessing the pyrano[4,3,2-de]-1-benzopyrylium core structure were isolated from an extract of blackcurrant seeds. Their chemical structures were elucidated by spectral methods and confirmed by chemical synthesis involving blackcurrant anthocyanins and p-coumaric acid. It is postulated that this condensation reaction plays a significant part in the evolution of red wine colour. [Copyright &y& Elsevier]

Addition of anthocyanins with nucleophilic agents normally occurs at the C-4 centre and the isolation of C-2 adducts between acetone and cyanidin-3- and delphinidin-3-rutinosides is the first definitive demonstration of the reactivity of this carbon site. These C-2 addition products were isolated as diastereoisomers and their chemical structures elucidated by 1D and 2D NMR spectroscopy. [Copyright &y& Elsevier]