| Co-Investigator(Kenkyū-buntansha) |
YOSHIZAWA Yuko Hokkaido Bunkyo Jr.College, Associate Pro., 助教授 (20269202)
SATO Hiroji Hokkaido Univ., Fac.of Agr., Experiment Farms,, 農学部・付属農場, 助教授 (20002074)
TOSHIMA Hiroaki Hokkaido Univ., Fac.of Agr., Instructor, 農学部, 助手 (50237088)
OIKAWA Hideaki Hokkaido Univ., Fac.of Agr., Instructor, 農学部, 助手 (00185175)
YOSHIHARA Teruhiko Hokkaido Univ., Fac.of Agr., Associate Pro., 農学部, 助教授 (90002071)
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| Research Abstract |
In the project "Chemistry and New Development of Phytotoxin", three main themes were investigated for past three years from 1994 to 1997, and the results are summerized as follows.
1. Synthetic Studies of Bioactive Natural Products
Tautomycin has an antifungal activity against phytopathogenic fungus, Sclerotinia sclerotiorum and a potent inhibitory activity against protein phosphatase. Stereocontrolled total synthesis has been achieved through key aldol coupling of two large subunits, aright-hand ketone (C_1-C_<21>) and a left-hand aldehyde (left from C_<22>). The C_1-C_<10> segment was synthesized through aremote stereochemical control process using a spiroketal template. The first synthesis of oscillatoxin D,which has antileukemic activity, has been completed by intramolecular Michael-type addition as a key step based on a possible biomimetic pathway.
2. Bioorganic Chemistry and Bioactivity of Phytotoxins
Several phytotoxins were isolated from phytopathogenic microorganisms in order to n
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ot only elucidate its role in ecological chemistry but also discover useful plant growth regulators. Practical synthetic method of coronatine has been developed. Similarties of the biological activities of coronatine to those of jasmonic acid in four jasmonate-responsive assay systems, namely in assays for tuber-inducing activity, for cell expansion-inducing activity, for cell division-inhibiting activity and for senescence-promoting activity. In all these assays, coronatine activities exhibited 100 to 10000 times higher than those of jasmonic acid in terms of the threshold concentration for activity. Determination of the stereochemistry and the total synthesis of altemaric acid has been achieved. Three altemaric acid analogs have been isolated and plausible biosynthetic routes have been suggested. The structures and stereochemistries of new bioactive compounds, cepaciamide A,abscisterol A and AAL-toxin, have been elucidated by spectroscopic and synthetic methods.
3. Diels-Alderase in the Biosynthesis of Phytotoxins
The biological Diels-Alder (DA) reaction has been studied with several phytotoxins, betaenone B,chaetoglobosin A,solanapyrone A and macrophomic acid. In the biosynthesis of, partially purified enzyme is able to catalyze intramolecular DA reaction of arising from through oxidation to give optically pure solanapyrone A (99%ee). Further cell free system from Macrophoma commelinae catalyzed intermolecular DA reaction phosphoenolpyruvate derived from (2R)-2-phosphoglycerate and alpha-pyrone to give an intermediate which was converted to macrophomic acid through removal of phosphoric acid and carbon dioxide. These enzymes that catalyze preceding reaction of the cycloaddition also catalyze DA reaction, that is bifunctional enzymes. Less
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