Generation of decarboxylated and dehydrogenated gomphrenins during heating of Basella alba L. fruit juice containing high levels of betacyanin pigments was monitored by LC-DAD-ESI-MS/MS. The presence of principal decarboxylation products, 2-, 17-, and 2,17-decarboxy-gomphrenins, their diastereomers, as well as minor levels of their dehydrogenated derivatives are reported. In addition, determination of molecular masses of decarboxylated gomphrenins by high-resolution mass spectrometry (LCMS-IT-TOF) was performed. Enzymatic deglucosylation of decarboxylated and dehydrogenated gomphrenins resulted in the generation of betanidin diagnostic derivatives for further identification processes. In addition, experiments were conducted to prove that the position of glucosylation of the chromophoric part of betacyanins (betanidin part) has decisive influence on different chromatographic properties of their decarboxylated derivatives.
Keywords: Basella alba; Malabar spinach; betacyanins; betalains; betanidin; decarboxylated and dehydrogenated gomphrenins; plant pigments.