2.4- dihydroxy-7-methoxy-1,4- -benzoxazin

Survival after 24 h and the number of aphids feeding were determined at 4 mM compound in the diet. Reproductive index (number of nymphs/ average number of adults) was determined at 0.15 mM compound in the diet. Values are the average of three samples of ten aphids each. For reproduction studies five samples were used. Standard errors were always less than 10%. DIMBOA 2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one. 

Oikawa, A., Ebisui, K., Sue, M., Ishihara, A., and Iwamura, H. 1999. Purification and characterization of a p-glucosidase specific for 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) glucoside in maize. Z. Naturforsch. C Biosci. 54, 181-185... 

Wu, H., Haig, T., Pratley, J., Lemerle, D., and An, M. 1999. Simultaneous determination of phenolic acids and 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one in wheat (Triticum aestivum L.) by gas chromatography-tandem mass spectrometry. J. Chromatogr. A 864, 315-321... 

DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) is a cyclic hydroxamic acid produced by members of the Gramineae as a defense against herbivores or microbial pathogens [60]. Maize CYP71C1 catalyzes the hydroxylation of indolin-2-one at the 3-position... 

DIMBOA (2,4-dihydroxy-7-methoxy-l/4-benzoxazin-3-one) and MBOA (6-methoxy-benzoxazolin-2-one) are showed as an example physicochemical descriptor like logP (partition coefficient between octanol and water) constitutional descriptors like the number of a specified atom or bond (number of carbons, hydrogens, oxygens, nitrogens, single and aromatic bonds, total number of atoms and bonds) and molecular weight quantum-mechanical descriptors like HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital). 

It is significant that oat plants, which are known to contain the Fe3+ complexor, 2,4-dihydroxy-7-methoxy-l,4-benzoxazin-3-one (128), do not show any significant accumulation of plutonium, or the other actinides. It is possible that this complexing agent is located within plant cells which do not come into contact with the cation transporting mechanisms. Although there is evidence of the existence of microbial hy-droxamates in soil and that hydroxamates do become concentrated in plants (129), there has been no evidence presented yet that hydroxamates are the agents responsible for plutonium uptake into plants. On the other hand there is evidence that EDTA and DTPA can stimulate actinide concentration in plants (See Table 6). 

Polarography has been used (86JOC3542) to determine very small concentrations of the open-chain tautomer of 2,4-dihydroxy-7-methoxy-l,4-benzoxazin-3-one (see 46A in Section II,B,l,b). 

Hydrolytic Dehalogenation Simazine was shown by Roth (1957) to degrade in the presence of com extracts, but was stable in the presence of extracts from a susceptible wheat crop. Castelfranco et al. (1961) described a similar nonenzyme constituent of expressed com sap that hydrolyzed simazine to hydroxysimazine [2,4-bis(ethylamino)-6-hydroxy-y-triazine]. Wahlroos and Virtanen (1959) and Hamilton (1964) have established that the catalytic conversion of simazine to hydroxysimazine in roots and shoots of resistant species is caused by 2,4-dihydroxy-7-methoxy-l,4-benzoxazin-3-one (benzoxazinone) or its 2-glucoside as follows ... 

Shimabukuro et al. (1966) identified 2-chloro-4-amino-6-isopropylamino-i-triazine (G-30033) as a major metabolite in shoots of mature pea plants. These results indicated that a second mechanism for tolerance to atrazine existed in some moderately susceptible plants. Later, Shimabukuro (1967a) was able to demonstrate that atrazine could be metabolized independently in both roots and shoots of young pea plants to 2-chloro-4-amino-6-isopropylamino-.t-triazine. This metabolite was much less phytotoxic than the parent compound. The metabolism of atrazine in resistant com and sorghum, in intermediately susceptible pea, and in highly susceptible wheat was reported by Shimabukuro (1967b). This study revealed two possible pathways for metabolism of atrazine in higher plants. All species studied were able to metabolize atrazine by TV-deal kyI ation of either of the two alkyl groups present. Com and wheat that contain the cyclic hydroxyamate (2,4-dihydroxy-7-methoxy-l,4-benzoxazine-3-one) also metabolized atrazine by conversion to hydroxy-atrazine (G-34048). Subsequent metabolism was postulated to be by conversion to more polar compounds. 

DIMBOA (2,4-dihydroxy-7-methoxy-l, 4-benzoxazin-3-one) play an important role in the chemical defense of cereals against insects, pathogenic fungi and bacteria (Niemeyer, 1988). Researches with maize indicate thatmycorrizal colonization induced accumulation of DIMBOA and increase in transcript levels of Bx9. Concentrations of DIMBOA in maize roots inoculated both G. mosseae and Rhizoctonia solani were significantly higher than those roots inoculated separately with G. mosseae or Rhizoctonia solani. 

Hartenstein, H., Lippmann, T. and Sicker, D. 1992. An efficient procedure for the isolation of pure 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA) from maize. Ind. J. Heterocycl. Chem. 2, 75-76... 

Smissman, E. E., Corbett, M. D., Jenny, N. A., and Kristiansen, O. 1972. Mechanism of transformation of 2,4-dihydroxy-1,4-benzoxazin-3-ones and 2-hydroxy-2-methyl-4-methoxy-1,4-benzoxazin-3-one to 2-benzoxazolinone. J. Org. Chem. 37, 1700-1704... 

Reimann, J. E. and R. U. Bjerrum Biosynthesis of 2,4-dihydroxy-7-methoxy-2H-l,4-benzoxazin-3-one. Tetrahedron Letters 211 (1964). 

APCI has become a popular ionization source for applications of coupled HPLC-MS. Figure 1.33 shows an example of an application of HPLC-APCI coupling [79]. It shows the analysis obtained from extracts of maize plants. Six compounds are identified by mass spectrometry. These compounds have been identified as glucoconjugated DIMBOA (2,4-dihydroxy-7-methoxy-l,4-benzoxazin-3-one) and similar molecules that differ by the number of methoxy groups in the benzene ring and/or by the N-O methylation of the hydroxamate function. This example clearly shows the influence of the analyte on the type of observed molecular species. Indeed, the presence of an acidic group in the compound from peak 1 allows mainly the detection of deprotonated molecular ions, whereas the compound from peak 4 does not contain an acid group and thus leads only to the formation of adduct ions. 

We have therefore been interested in the synthesis of the corresponding aglucone 5-acetyl-2,4-dihydroxy-2//-l,4-benzoxazin-3(4i/)-one (5-acetyl-DIBOA). However, when the appropriate precursor 5-acetyl-4-hydroxy-2-methoxy-2//-l,4-benzoxazin-3(4/7)-one was subjected to a boron trichloride ether cleavage followed by hydrolysis with silver carbonate/water according to a reported method [110], the expected aglucone was not obtained. Instead of, 4-ABOA was isolated [121]. In... 

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