New pyranoanthocyanins from blackcurrant seeds

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.