Profiles of betacyanins in epidermal layers of grafted and light-stressed cacti studied by LC-DAD-ESI-MS/MS.

Profiles of betacyanins present in light-stressed stems of different cactus species and nonstressed but genetically aberrated red pigmented cacti of Gymnocalycium mihanovichii cv. ;Hibotan' Britton & Rose, which are known as grafted cacti, were compared. The identities of all the pigments in the cacti were characterized for the first time. The identification of acylated and nonacylated betacyanins was performed by means of mass spectrometry and UV-vis diode array detection coupled to high-performance liquid chromatography. The most indicative pigments of the stressed cacti, 5''-O-E-feruloyl-2'-O-beta-apiosyl-betanin and 5''-O-E-sinapoyl-2'-O-beta-apiosyl-betanin, as well as their diasteromers, were the prevailing betacyanins in Hylocereus polyrhizus , Epiphyllum phyllanthus , and Rhipsalis rhombea . Stressed Rhipsalis regnellii stems contained the sinapoylated betacyanins accompanied only by traces of the feruloylated derivatives. In addition, high contents of 2'-O-apiosyl-betanin were frequently observed in the samples with the highest concentration found in stressed Schlumbergera x buckleyi (T. Moore) Tjaden. These pigments were also detected, but at low levels, in the Hibotan pink, red, and violet scions, which were not light-stressed. In the Hibotan scions, the most abundant were the polar betacyanins: betanidin 5-O-beta-sophoroside and betanin. In most of the stressed samples, betanin was present at relatively low levels.