73 稲こうじからの細胞分裂毒USTILOXINおよび類縁ペプチドの構造・作用(ポスター発表の部)

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The false smutted balls growing parasitically on panicles of rice plant (in Japanese, Ina-kouji) are caused by a pathogen, Ustilaginoidea virens. Ingestion of such rice plant caused poisoning to domestic animals. Deep red pigments, ustilaginoidins, have been isolated from the ether extract of the balls but these compounds were not the causative principles as the phytotoxin or the mycotoxin. We report on the isolation, the structure and the bilogical activities of a toxin, ustiloxin (1), which was isolated from the water extract of the balls, as well as on the mode of action of a mycotoxin, phomopsin A (5), whose structure is closely related to that of 1. Absolute structure of 1 was determined to be a unique cyclic tetra peptide containing a 13-membered ring including an ether linkage, by combination of spectroscopic, amino acid and X-ray chrystallographic analyses. The compound induces an abnormal swelling of the seedling roots. Such a symptom is induced also by rhizoxin (2), a potent antimitotic agent. 1 strongly inhibits the polymerization of porcine brain tubulin and also shows potent cytotoxicity against broad range of tumor cells. Phomopsin A (5), structurally similar to 1, is also a potent antimitotic agent and inhibits tubulin polymerization. Its binding site on porcine brain tubulin was revealed to be identical with that of 2 and maytansine (3). It is interesting to note that 5 does not bind to fungal tubulin and shows no antifungal activity, whereas 2 and 3 are potent fungicides.
天然有機化合物討論会の論文
1992-09-10

73 稲こうじからの細胞分裂毒USTILOXINおよび類縁ペプチドの構造・作用(ポスター発表の部)

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