Precursors of 6-Methoxybenzoxazolinone in Maize and Wheat Plants, their Isolation and Some of their Properties.

12,4-Dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H) (11) reported that a lyophilized water extract from corn was only slightly inhibitory to most isolates of ECZ; however, it was strongly inhibitory to most other soft rot bacteria. The observed effect was an extension of the duration of the lag phase of growth. No significant effect on growth rate was detected after the lag phase. It was suggested that the differential inhibitor(s) to soft rotting Erwinia species present in the extract could be involved in the resistance of corn to these bacteria.-'Research cooperative with the College of Agricultural and Life Sciences,

Section: Methodsmentioning

confidence: 99%

“…Several closely related cyclic hydroxamic acids have been isolated as glucosides from corn (12,20). The principal hydroxamic acid in aqueous extracts of corn is 2,4-dihydroxy-7-methoxy-2H-l,4-benzoxazin-3(4H)-one (DIMBOA), which decomposes to 6-methoxy-2-benzoxazolinone (MBOA) in aqueous solutions (19,23).…”

mentioning

confidence: 99%

2,4-Dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one, an Inhibitor from Zea mays with Differential Activity against Soft Rotting Erwinia Species

Corcuera¹,

Woodward²,

Helgeson³

et al. 1978

“…The nonenzymatic hydroxylation reaction was catalyzed by a cyclic hydroxamate isolated from corn and identified as benzoxazinone (10,11,19,28).…”

Section: Miaterials and Methodsmentioning

confidence: 99%

Glutathione Conjugation

Shimabukuro¹,

Frear²,

Swanson³

et al. 1971

167

The primary factor for atrazine selectivity in corn (Zea mays) is the activity of a soluble enzyme, glutathione Stransferase, which detoxifies atrazine by catalyzing the formation of an atrazine-glutathione conjugate (GSatrazine). The nonenzymatic, benzoxazinone-catalyzed hydrolysis of atrazine to hydroxyatrazine contributed to the total resistance of corn to atrazine, but the nonenzymatic detoxication pathway does not seem to be essential for resistance. All corn lines investigated, except for susceptible GT112, rapidly detoxified atrazine by glutathione conjugation. Only GT112 had low glutathione S-transferase activity. Hydroxyatrazine was found in significant quantities only when atrazine was introduced initially into the roots. The amount of hydroxyatrazine formed was nearly equal for susceptible GT112 and most of the resistant corn lines investigated. This investigation indicates that some plants protect themselves against toxic organic hialide compounds witlh a mechanism similar to that known to exist in animals. and the closely related metabolite 'y-glutamyl-S-(4-ethylamino-6-isopropylamino-2-s-triazino)cysteine from resistant sorghum indicated the presence of a third metabolic pathway for atrazine degradation (15). N-Dealkylation was previously identified as another atrazine degradation pathway in plants (23,24). The recovery of atrazine-inhibited photosynthesis in both sorghum and corn leaf discs was accompanied by a rapid conversion of atrazine to GS-atrazine rather than to hydroxyatrazine (24, 25). The two peptide-conjugated metabolites will be referred to collectively in this paper as GS-atrazine since both compounds chromatograph as a single spot (metabolite B) (24) upon separation by thin layer chromatography (15).The isolation and characterization of the enzyme, glutathione S-transferase, from corn, sorghum, and other resistant species, indicated an enzymatic reaction for the formation of GS-atrazine (6). The presence of this highly active enzymatic pathway in corn leaf tissue suggests that the formation of GS-atrazine is the key factor in the resistance of corn to atrazine (25). This investigation was undertaken to show that the principal factor for atrazine selectivity in corn was the enzymatic formation of GS-atrazine rather than the nonenzymatic hydrolysis of atrazine to hydroxyatrazine as reported (3,7,11,18). MIATERIALS AND METHODSThe substituted s-chlorotriazines, atrazinel and simazine, are two of the most widely used herbicides for the control of annual weeds in fields of corn and sorghum. Both of these herbicides are believed to be metabolized similarly in plants, and their mode of action is the same. These compounds are effective inhibitors of the Hill reaction in photosynthesis (5, 16) and are known to reduce the rate of CO2 fixation in plants (1,27,29).Resistance of corn to the 2-chloro-s-triazines has been attributed to the nonenzymatic detoxication of the herbicides to hydroxyatrazine and hydroxysimazine (3,7,11,18). The nonenzymatic hydroxylation reaction was catalyzed by a...

“…1, Ila) from rye (6) and DIMBOA-glucoside (IIc) from wheat and maize (20). These glucosides were enzymically hydrolyzed to yield DIBOA (Va) and DIMBOA (Vc), respectively (19,20).…”

Section: Introductionmentioning

confidence: 99%

“…1, Ila) from rye (6) and DIMBOA-glucoside (IIc) from wheat and maize (20). These glucosides were enzymically hydrolyzed to yield DIBOA (Va) and DIMBOA (Vc), respectively (19,20). The aglucones were unstable and could be converted to their corresponding benzoxazolinones, ' Research cooperative with the College of Agricultural and Life Sciences,…”

mentioning

confidence: 99%

Identification of 1,4-Benzoxazin-3-ones in Maize Extracts by Gas-Liquid Chromatography and Mass Spectrometry

Woodward¹,

Corcuera²,

Schnoes³

et al. 1979

Gas-liquid chromatography-mass spectrometry (GLC-MS) has been used for the separation, detection, and identification of 1,4-benzoxazin-3-ones (hydroxamic acids and lactams) and benzoxazolinones found in maize (Zea mays L.) extracts. Compounds of interest were partitioned into ethyl acetate from aqueous maize seedling extracts. For analysis by GLC-MS, trimethylsilyl derivatives were prepared, chromatographed on a column of 3% OV-1, and detected in the mass spectrometer. Mass spectra were obtained for all peaks present in extracts of four maize lnes. A data comparison system was developed for relating unidentified spectra to the spectra of the reference compounds. Based on spectral comparisons, three hydroxamic acids (2,4-dihydroxy-2H-1, 4-benzoxazin-3(4H)-one; 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one; and 2,4-dihydroxy-7,8-dimethoxy-2H-1,4-benzoxazin-3(4H)-one), three lactams (2-hydroxy-2H-1,4-benzoxazin-3(4H)-one; 2,7-ihydroxy-2H-I,4-benzoxazin-3(4H)-one; and 2-hydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one), one benzoxazolinone (6-methoxybenzoxazolinone), and two organic acids (malic and aconitic) were identified in the extracts. In addition, one other hydroxamic acid and one other related compound were tentatively identified based on mass spectral evidence.The existence of naturally occurring 1,4-benzoxazin-3-ones was first reported by Virtanen and his co-workers who identified two hydroxamic acids, DIBOA5-glucoside (Fig. 1, Ila) from rye (6) and DIMBOA-glucoside (IIc) from wheat and maize (20). These glucosides were enzymically hydrolyzed to yield DIBOA (Va) and DIMBOA (Vc), respectively (19,20). The aglucones were unstable and could be converted to their corresponding benzoxazolinones, ' Research cooperative with the College of Agricultural and Life Sciences,