Structure of petanin, an acylated anthocyanin isolated from solanum tuberosum, using homo‐and hetero‐nuclear two‐dimensional nuclear magnetic resonance techniques

The anthocyanin, petanin, was isolated from the acidified methanolic extracts of blue tubers of the potato ( Solanum tuberosum ) by successive application of ion exchange chromatography, droplet counter‐current chromatography and gel filtration. The full structure, petunidin 3‐ O ‐[6‐ O ‐(4‐ O‐E‐p ‐coumaroyl‐α‐L‐rhamnopyranosyl)‐β‐D‐glucopyranoside]‐5‐ O ‐β‐D‐glucopyranoside, with both the glucopyranose rings assuming a 4 C 1 chair conformation and the rhamnopyranose ring assuming a 1 C 4 chair conformation, was elucidated by means of chemical degradation, chromatography and spectroscopy, especially homo‐ and hetero‐nuclear two‐dimensional nuclear magnetic resonance techniques.