DIMBOA

Melanson D, Chilton M D, Masters-Moore D, Chilton WS (1997), A deletion in an indole synthase gene is responsible for the DIMBOA-deficient phenotype of bxbx maize , Proc. Natl. Acad. Sci. USA, 94, 13345-13350. 

In Figure 2 an example is given the 2D structure of DIMBOA is converted in a optimized 3D structure where the torsion angles have the biggest impact on the energy of the molecule and dictate the overall 3D molecular shape. 

Table 1 Calculation of some molecular-based descriptors for BOA, DIMBOA and MBOA. Physicochemical descriptor like logP (partition coefficient between octanol and water) constitutional descriptors like the number of a specified atoms or bonds (number of carbons, hydrogens, oxygens, nitrogens, single and aromatic bonds, the total number of atoms and bonds) and molecular weight quantum-mechanical descriptors like HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital).

Examples of statistical analysis for QSAR developing using different techniques is given in Table 2 that shows the prediction of the Daphnia magna toxicity for allelochemicals (BOA, DIMBOA and MBOA) using QSARs models obtained with different statistical techniques (PLS, MLR, and Neural Networks). 

Triticum speltoides Fla Kslo. Wild oat (Avena spp.). Ts8, TslO, Ts22, Ts25 - higher amounts of DIMBOA Quader et al. 2001... 

Quader M, Daggard G, Barrow R, Walker S, Sutherland MW (2001) Allelopathy, DIMBOA production and genetic variability in accessions of Triticum speltoides. 3 Chem Ecol 27 747-760... 

Effects of Gramine, DIMBOA and DIMBOA-Glucoside on ScfUzaph-Ci gAxmcnum feeding on artificial diets... 

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. 

M. Czjzek, M. Cicek, V. Zamboni, D. R. Bevan, B. Henrissat, and A. Esim, The mechanism of substrate (aglycon) specificity in P-glucosidases is revealed by crystal structures of mutant maize p-glucosidase-DIMBOA, -DIMBOAGlc, and -dhurrin complexes, Proc. Natl. Acad. Sci. USA, 97 (2000)13555-13560. 

Ruiz, and P. Castanera. A high performance liquid chromatography method for quantification of diboa, dimboa and mboa from aqueous extracts of corn HV047 and winter cereal plants. J Liq Chro-matogr 1994 17(12) 2651-2665. 

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. 

DIMBOA-GIc OMe H Zea mays (Poaeceae)35 Triticum aestivum (Poaceae)81 Secale cereale (Poaceae)41 Coix lachryma jobi (Poaceae)54... 

The entire subject has been reviewed in detail several times.32,56,57,65 Recently, a new adsorptive method for the isolation of DIMBOA has been reported.49 The impact of benzoxazinoids on the western corn rootworm (Diabrotica virgifera LeConte) development has been studied.17 The allocation of a hydroxamic acid and biomass during vegetative development of rye has been investigated.27 Effects of benzoxazinoids from maize on survival and fecundity of aphids have been explored.13 DIMBOA concentrations have been measured in various isolines of wheat and corresponding plant introduction lines.55 The variation of the content of several benzoxazinoids in relation to the age and plant organ has been determined in maize plants.12... 

Two reviews cover the whole synthetic literature in the field until 1997.1,67 Suitable syntheses for the main aglucones DIBOA68 and DIMBOA64 74 have been reported, as well as a general diastereoselective glucosidation method to form DIBOA-GIc, DIMBOA-GIc and other benzoxazinone glucosides.46... 

Most likely, the two main pathways consist of reactions of the electrophilic ring-opened aldehyde form of the hemiacetal with bionucleophiles and of reactions of a unique multi-centered cationic nucleophile that can be generated from DIMBOA by N-O-fission.37 Recently, we reported a novel hypothesis for the mode of bioactivity based on the formation of 3-formyl-6-methoxybenzoxazolin-2(3H)-one (FMBOA) by formal dehydration of DIMBOA.40 FMBOA was proven to be a potent formyl donor towards typical nucleophiles occurring in biomolecules and could, if formed under natural conditions, also lead to biological effects by formylation of biomolecules. The mechanism of this new dehydration was elucidated with [2-13C]-DIMBOA.33... 

Adapted species may have developed, however, strategies which enable them to survive allelopathic attacks. One of those strategies certainly includes detoxification of absorbed allelochemicals by constitutive or inducible pathways. Metabolization and detoxification are known reactions in a number of crops upon application of diverse synthetic herbicides.38 Enhanced herbicide detoxification is an important factor in the development of nontarget-site cross-resistance and multiple resistance. It is reasonable to expect comparable strategies in plants that are relatively resistant to allelochemicals such as DIBOA, DIMBOA, and their derivatives. Especially in ecosystems where co-existing species have to be adapted to each other, detoxification of absorbed allelochemicals may play a crucial role under defined circumstances. 

Cambier, V., Hance, T. and de Hoffmann, E. 2000. Variation of DIMBOA and related compounds content in relation to the age and plant organ in maize. Phytochemistry 53, 223-229... 

Glawischnig, E., Eisenreich, W., Bacher, A., Frey, M., and Gierl, A. 1997. Biosynthetic origin of oxygen atoms in DIMBOA from maize NMR studies with 1802. Phytochemistry 45, 715-718... 

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... 

Larsen, E. and Christensen, L. P. 2000. Simple method for large scale isolation of the cyclic arylhydroxamic acid DIMBOA from maize (Zea mays L ). J. Agric. Food Chem. 48, 2556-2558... 

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