First C-13-NMR assignments of betaxanthins

Due to their inherent liability towards highly acidic conditions previously considered to be a prerequisite for data acquisition, betaxanthin structure dereplication by NMR spectroscopy has been scarcely reported and was, hitherto, exclusively based on H-1-NMR data interpretation. Applying only slightly acidic conditions, we herein report the first C-13-NMR data of two betaxanthins, i.e., indicaxanthin (1), isolated from yellow-orange cactus pear fruits (Opuntia ficus-indica [L.] MILL. CV. 'Gialla'), and of miraxanthin V (2) from yellow Swiss chard petioles (Beta vulgaris L. ssp. cicla [L] ALEF. CV. 'Bright Lights'), as derived by gHSQC- and gHMQC-NMR experiments and inverse detection.