Metabolism of the Host-Selective Toxins Destruxin B and Homodestruxin B: Probing a Plant Disease Resistance Trait
摘要:
[GRAPHICS]Metabolism of the host-selective toxins destruxin B (1) and homodestruxin B (2) by plants resistant and susceptible to Alternaria blackspot (caused by the fungal pathogen Alternaria brassicae (Berk,) Sacc,) was established using synthetic radiolabeied compounds. The toxins are transformed into the less phytotoxic hydroxydestruxins 3 and 4. The rate of metabolic transformation was correlated with the plant's disease resistance, i.e., significantly faster rates were observed for plants resistant to the pathogen, Efficient syntheses of 1, 2, 3, and 4 are described.
Probing Host-Selective Phytotoxicity: Synthesis of Destruxin B and Several Natural Analogues
摘要:
The syntheses of the host-selective phytotoxin destruxin B [cyclo(beta Ala-Hmp-Pro-Ile-MeVal-MeAla), Hmp = (2R)-2-hydroxy-4-methylpentanoic acid], and the closely related natural analogues homodestruxin B (MeVal --> MeIle), desmethyldestruxin B (MeVal --> Val), hydroxydestruxin B (Hmp --> Dhmp, Dhmp = (2R)-2,4-dihydroxy-4-methylpentanoic acid), and hydroxyhomodestruxin B (MeVal --> MeIle, Hmp-Dhmp) are described. In each case, the MeAla-beta Ala linkage was formed by cyclization and the precursor linear hexadepsipeptides were formed by condensing two three-residue fragments. Radiolabeled samples of destruxin B, homodestruxin B, and hydroxydestruxin B were prepared by coupling [3-C-14]-beta -alanine to the appropriate pentadepsipeptide followed by cyclization. A noteworthy feature of the synthesis involves the novel use of a Boc-hydrazide protecting group on dipeptides with a C-terminal N-methylalanine residue to inhibit the otherwise facile dioxopiperazine formation during peptide coupling.
Metabolism of the Host-Selective Toxins Destruxin B and Homodestruxin B: Probing a Plant Disease Resistance Trait
作者:M. Soledade C. Pedras、Irina. L. Zaharia、Yuanzhu Gai、Kevin C. Smith、Dale E. Ward
DOI:10.1021/ol991042z
日期:1999.11.1
[GRAPHICS]Metabolism of the host-selective toxins destruxin B (1) and homodestruxin B (2) by plants resistant and susceptible to Alternaria blackspot (caused by the fungal pathogen Alternaria brassicae (Berk,) Sacc,) was established using synthetic radiolabeied compounds. The toxins are transformed into the less phytotoxic hydroxydestruxins 3 and 4. The rate of metabolic transformation was correlated with the plant's disease resistance, i.e., significantly faster rates were observed for plants resistant to the pathogen, Efficient syntheses of 1, 2, 3, and 4 are described.
Probing Host-Selective Phytotoxicity: Synthesis of Destruxin B and Several Natural Analogues
作者:Dale E. Ward、Yuanzhu Gai、Ryszard Lazny、M. Soledade C. Pedras
DOI:10.1021/jo015953+
日期:2001.11.1
The syntheses of the host-selective phytotoxin destruxin B [cyclo(beta Ala-Hmp-Pro-Ile-MeVal-MeAla), Hmp = (2R)-2-hydroxy-4-methylpentanoic acid], and the closely related natural analogues homodestruxin B (MeVal --> MeIle), desmethyldestruxin B (MeVal --> Val), hydroxydestruxin B (Hmp --> Dhmp, Dhmp = (2R)-2,4-dihydroxy-4-methylpentanoic acid), and hydroxyhomodestruxin B (MeVal --> MeIle, Hmp-Dhmp) are described. In each case, the MeAla-beta Ala linkage was formed by cyclization and the precursor linear hexadepsipeptides were formed by condensing two three-residue fragments. Radiolabeled samples of destruxin B, homodestruxin B, and hydroxydestruxin B were prepared by coupling [3-C-14]-beta -alanine to the appropriate pentadepsipeptide followed by cyclization. A noteworthy feature of the synthesis involves the novel use of a Boc-hydrazide protecting group on dipeptides with a C-terminal N-methylalanine residue to inhibit the otherwise facile dioxopiperazine formation during peptide coupling.