A HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY METHOD FOR QUANTIFICATION OFDIBOA, DIMBOA, AND MBOA FROM AQUEOUS EXTRACTS OF CORN AND WINTER CEREAL PLANTS

A new HPLC method is described for the quantification of aglycones der ived from cyclic hydroxamic acids: DIMBOA -dihydroxy-7-methoxy-2H-1,4- benzoxazin-3(4H)-one), its degradation product MBOA (6-methoxybenzoxaz olinone) and the demethoxy analogue DIBOA (2,4-dihydroxy-2H-1 ,4-benzo xazin-3(4H)-one) in crude aqueous solutions from homogenized cereal ti ssues. After hydrolysis of beta-glycosides to aglycones, extracts of c ereal samples were chromatographed on a PRP-1 column using a gradient of tris/citric acid and methanol/acetonitrile, and monitored at 288 nm . The three compounds were separated within 26 min. The minimum detect ion limit for all of them was 50 pmol. The recovery percentage was 100 % for DIBOA, 87% for DIMBOA and 96% for MBOA. The levels of aglycones were determined in aqueous extracts from corn and winter cereal seedli ngs (20-100 mg), ranging from 3.80 to 11.50 mg DIBOA/g dry weight and 4.75 to 100.43 mg DIMBOA/g dry weight.