13C-nmr data of three tetraoxygenated xanthones from centaurium pulchellum

Abstract EN

Three pigments tetra oxygenated xanthene's have been isolated from Centauries pulchellum (1, 8- dihydroxy 3, 5- dimethyl xanthine 1, 1, 8-dihydroxy 3,7-dimethoxy xanthine 2 and 1- hydroxyl -3, 7, 8 trimethoxy xanthine 3).

As the 13C NMR data of these three tetra oxygenated xanthene's have not been reported, they were measured and multiplicity assignments made using polarization transfer pulse sequences (DEPT) to distinguish between methyl, methylene, methane and quaternary carbons.