CHARACTERIZATION OF THE ANTIRADICAL ACTIVITY OF BETALAINS FROM BETA-VULGARIS L. ROOTS

Betalains (betacyanins and betaxanthins), the main pigments of red bee t (Beta vulgaris) roots, showed an antiradical effect when measured by the destruction of the 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphon ic acid (ABTS) free radical generated by the horse-radish peroxidase/h ydrogen peroxide-mediated oxidation of ABTS. The antiradical activity of betacyanins was greater than that of the betaxanthins and increased with the pH of the reaction medium. The different antiradical propert ies shown by both types of betalain is discussed in light of the respe ctive ease with which it is possible to withdraw one electron from the ir molecules and the stability of their corresponding radicals. (C) 19 98 John Wiley & Sons, Ltd.