Chemistry and Phytotoxicity of Thaxtomin A Alkyl Ethers
| Autor: | Stuart B. Krasnoff, Donna M. Gibson, Michael J. Wach, Emil B. Lobkovsky, Rosemary Loria |
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| Rok vydání: | 2005 |
| Předmět: |
Models
Molecular Indoles Stereochemistry Ether Crystallography X-Ray Plant Roots Streptomyces Piperazines Structure-Activity Relationship chemistry.chemical_compound Moiety Alkyl Plant Diseases chemistry.chemical_classification biology Herbicides General Chemistry Phytotoxin Lettuce biology.organism_classification chemistry Seedlings Phytotoxicity Epimer Crystallization General Agricultural and Biological Sciences Isopropyl |
| Zdroj: | Journal of Agricultural and Food Chemistry. 53:9446-9451 |
| ISSN: | 1520-5118 0021-8561 |
| Popis: | The thaxtomin phytotoxins (1 and 2) from scab-producing Streptomyces pathogens of the potato are 2,5-dioxopiperazines consisting of modified l-tryptophanyl and l-phenylalanyl units. Thaxtomin A (1) is hydroxylated at C-14, the alpha carbon of the modified l-phenylalanyl moiety. Refluxing thaxtomin A in acidified MeOH, EtOH, and i-PrOH afforded C-14 thaxtomin A methyl- (3a and 3b), ethyl- (4a and 4b), and isopropyl- (5a and 5b) ethers, respectively, in both the 11S,14R (3a, 4a, and 5a) and 11S,14S (3b, 4b, and 5b) configurations. Crystal structures were determined for 3a and 4a. Extensive NMR as well as other spectroscopic data supported structural assignments for all of the derivatives. The 11S,14R-configured derivatives were slightly less potent than the natural products (1 and 2) as inhibitors of lettuce seedling root growth, whereas the activity of the 11S,14S epimers was much reduced, indicating that the configuration at C-14 found in the naturally occurring thaxtomins is essential for biological activity. Among the 11S,14R-configured compounds, potency decreased with an increasing size of the substituted alkoxy group. |
| Databáze: | OpenAIRE |
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