Identification and Determination of Betacyanins in Fruit Extracts of Melocactus Species

Betacyanin pigments were studied in edible fruits of four Melocactus species, M. violaceus Pfeiff., M. bahiensis (Britton & Rose) Luetzelb, M. amoenus (Hoffm.) Pfeiff., and M. curvispinus Pfeiff., by means of chromatographic and mass spectrometric techniques. The main pigment constituent, melocactin, endogenously present in the Melocactus species, was identified as betanidin 5-O-β-sophoroside betacyanin, previously known as “bougainvillein-r-I”. The highest total concentration of betacyanins was found in fruits of M. amoenus (∼0.08 mg/g). Except for melocactin being the most abundant betacyanin (34.8–38.8%) in the analyzed species, a presence of its malonylated derivative, mammillarinin (15.2–19.9%), as well as more hydrophobic feruloyled and sinapoyled melocactins was confirmed by additional co-chromatographic experiments with authentic reference betacyanins. The acyl migration isomers of the malonylated betacyanins as well as a presence of 5′′-O-E-sinapoyl-2′-O-apiosyl-betanin (2.3–3.0%) found frequently in light-stressed cacti was also acknowledged.