Abstract: Radish anthocyanins (RA) were purified by ultrafiltration and XAD-4 macroporous adsorption resin. PA was identified to consist mainly of anthocyanin diglucoside by Fourier transform infrared spectroscopy (FT-IR) and mass spectrometry (MS), and its solubility in 4 ℃ cold water and 65% ethanol were 46.43% and 63.07%, respectively. Then RA was modified with glucosaccharase and the effect of pH, enzyme-to-substrate ratio and reaction temperature on the modification efficiency was optimized by orthogonal array design method. FT-IR and MS analyses indicated that the glycosidic bond of RA was specifically hydrolyzed by glucosaccharase into anthocyanin monoglycosides. The solubility of the modified anthocyanins in cold water and 65% ethanol was improved by 115.38% and 58.55%, respectively compared to the native counterpart. Furthermore, the hydroxyl radical scavenging activity of the modified anthocyanins, as determined using bromopyrogallol red oxidation assay, was significantly higher than that of native anthocyanins, but was slightly lower than that of procyanidine B2. Cytotoxicity evaluation suggested that the modified anthocyanins at concentrations from 5 to 40 μmol/L significantly inhibited the cancer cell growth of MHCC97L cells for 24 to 72 h in a concentration-dependent manner.

Key words: radish anthocyanins, purification, glucosaccharase modification, antioxidant capacity, cell growth inhibition