Gross degradation studies

Gross degradation studies in wheat show that after initial infection with F. graminearum, levels of deoxynivalenol increased until 6 weeks (9 5ppm) and then dropped by 73% (27). This degradation may be attributed to plant enzymes in the host (27) which structurally modify the trichothecene molecule. Using suspension cultures of the resistant cultivar Frontana, Miller showed that deoxynivalenol was converted into three products (21). One was and... 

Similar spectral and other degradation studies completely define the structures of two other alkaloids as (11 R = OH) and (11 R = H).9 As noted earlier, the compound (11 R = H) was found to be identical with an alkaloid isolated from another plant source. Another alkaloid was assigned the gross structure and stereochemistry of (11 R = H), except that ring d was shown to contain one methoxy-group rather than the methylenedioxy function. The location of the methoxy-function [either C(16) or C( 17)] remains to be assigned. 

Infrared spectroscopy continues to be one of the principal techniques for structural analysis of polymers and for identifying components of complex formulations. The distinctiveness of important vinyl, alkyl, and aryl chemical structures in the infrared such as ester, amide, nitrile, isocyanate, hydroxyls, amine, and sulfone makes it ideal for the first gross characterization of chemical types present and for following the reactions of these functional groups in curing or degradation studies. 

The most significant information in the gross analytical studies is the fact that lignin, even though altered, is the chemical constituent present in highest amounts in the most degraded woods. 

NMR studies reveal the gross chemical composition of OM, this technique cannot identify specihc compounds. However, the thermal degradative technique of analytical pyrolysis, especially when coupled with mass spectrometry, can provide information on the specihc compounds present in a sample. Bracewell et al. (1989), Saiz-Jimenez (1994), Kogel-Knabner (2000), and others have reviewed the application of pyrolysis techniques to OM studies. 

Aplin Barrett). Structure contains 34 amino acid residues, eight of which are rarely found in nature, including lanthi-onine (two alanines bonded to sulfur at the 6-carbons) and P -methyllanthionine. Structure E. Gross, J. L. Morrell, J. Am. Chem. Soc. 93, 4634 (1971). Confirmation of structure of nisin and its major degradation product M. Barber et ah, Experientia 44, 266 (1988). Partial synthesis K. Fukase er ah. Bull. Chem. Soc. Japan 59, 2505 (1986). Total synthesis K, Pukase et al, Tetrahedron Letters 29, 795 (1988), Biosynthetic study G. W. Buchman et ah, J. Biol. Chem, 263, 16260 (1988). Review A. Hurst, Adv. Appl. Microbiol. 27, 85-123 (1981). 

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