Mass spectrometry, deuterium NMR and TLC radioactivity analysis of 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA) 8, recovered from maize shoots grown in the presence of indole-[2H6] and 2-[14C]indole show that indole is a precursor of DIMBOA.
