Glucosides from MBOA and BOA Detoxification by Zea mays and Portulaca oleracea

Incubation of Zea mays cv. Nicco seedlings with 6-methoxybenzoxazolin-2(3H)-one (MBOA) led to a minor detoxification product hitherto only found in Poaceae. This new compound was identified as 1-(2-hydroxy-4-methoxyphenylamino)-1-deoxy-β-glucoside 1,2-carbamate (1) (methoxy glucoside carbamate) and represents an analogue to the previously described 1-(2-hydroxyphenylamino)-1-deoxy-β-glucoside 1,2-carbamate (glucoside carbamate) from benzoxazolin-2(3H)-one (BOA). In Portulaca oleracea var. sativa cv. Gelber treatment with BOA resulted in further unknown detoxification products, which were not synthesized in detectable amounts after BOA absorption in all other species tested. Compound 1 easily undergoes decay into BOA-5-O-glucoside (2). Z. mays seedlings, known to produce BOA-6-O-Glc on incubation with BOA, are able to transform BOA-5-OH into BOA-5-O-glucoside (2). Besides the known compounds, maize contained a formerly unseen product that accumulated during late stages of the detoxification process. It was isolated and identified as 1-(2-hydroxyphenylamino)-6-O-malonyl-1-deoxy-β-glucoside 1,2-carbamate (3) (malonyl glucoside carbamate).