Malonylated anthocyanins from bulbs of red onion, Allium cepa L.

Four cyanidin-based anthocyanins (1-4) were isolated from the red onion, Allium cepa L. Pigments 1 and 3 were identified as cyanidin 3-glucoside (Cy 3-Glc) and 3-malonylglucoside (Cy 3-MaGlc), respectively, by cochromatography with standard pigments. Anthocyanins 2 and 4 were respectively determined as cyanidin 3-laminaribioside (Cy 3-Lam) and 3-malonyllaminaribioside (Cy 3-MaLam), a new anthocyanin, mainly by NMR techniques. Malonylated anthocyanins 3 and 4 were found for the first time in red onions.