Formation of betanidin, the aglycone of the red–violet betacyanins, has been demonstrated by a two-step model assay system. In the first step, dihydroxyphenylalanine (Dopa) was incubated with a Dopa dioxygenase preparation from Amanita muscaria, resulting in the formation of 4, 5-seco-Dopa that spontaneously recyclized to betalamic acid. In the second step, a tyrosinase preparation from Portulaca grandiflora was added to the Dopa ...
