Occurrence of 2-(2-Hydroxy-4,7-dimethoxy-2H-1,4-benzoxazin-3-one)- β-ᴅ-glucopyranoside in Triticum aestivum Leaves and Its Conversion into 6-Methoxy-benzoxazolinone

Abstract

Abstract Cyclic hydroxamic acids occurring in the Gramineae have been reported to be involved in the resistance of cereals to fungi and insects. Here we describe the occurrence, in wheat leaves, of 1,4- benzoxazinone derivatives and their glucosylated forms, a major representative of which was found to be 2-(2-hydroxy-4,7-dimethoxy-2H -1,4-benzoxazin-3-one)-β-ᴅ-glucopyranoside. Owing to its spontaneous conversion into 6-methoxy-benzoxazolinone the corresponding aglucone could not be isolated following enzymic cleavage. We propose a plausible mechanism for this reaction which also explains the higher stability of other members of the 1.4-benzoxazinone family.