Chemistry and New Development of Phytotoxin

本课题从1994年至1997年三年中，对植物毒素的化学及新进展进行了三个方面的研究，主要结果如下：1.植物毒素的化学及新进展。生物活性天然产物的合成研究他莫霉素具有抗植物病原真菌核盘菌的活性和对蛋白磷酸酶的抑制活性。通过两个大亚基--右旋酮（C_1-C_2）和左旋醛（C_2-C_3）的关键羟醛偶联实现了立体控制全合成<21><22>。以<10>螺缩酮为模板剂，通过立体化学控制合成了C_1-C_2链段。具有抗白血病活性的黄曲霉毒素D的首次合成是通过分子内Michael型加成作为关键步骤，基于一条可能的仿生途径完成的.植物毒素的生物有机化学与生物活性从植物病原微生物中分离出几种植物毒素， ...更多信息 不仅阐明了它在生态化学中的作用，而且发现了有用的植物生长调节剂。提出了一种实用的冠菌素合成方法。冠菌素与茉莉酸在四种茉莉酸响应测定系统中的生物活性的相似性，即在块茎诱导活性、细胞扩增诱导活性、细胞分裂抑制活性和衰老促进活性的测定中。在所有这些试验中，冠菌素的活动表现出100至10000倍高于茉莉酸的阈值浓度的活动。确定了顺丁烯二酸的立体化学结构，实现了顺丁烯二酸的全合成。三个altemaric酸类似物已被分离和合理的生物合成路线已被提出。通过光谱和合成方法确定了新的生物活性化合物：头孢酰胺A、脱落酸甾醇A和AAL-毒素的结构和立体化学.植物毒素生物合成中的Diels-Alderase（DA）反应研究了几种植物毒素（betaenone B，chaetoglobosin A，solanapyrone A和macrophomic acid）的生物Diels-Alder反应。在生物合成中，部分纯化的酶能够催化分子内DA反应，通过氧化产生光学纯的茄吡喃酮A（99%ee）。此外，来自鸭茅茎点霉的无细胞系统催化分子间DA反应，磷酸烯醇丙酮酸衍生自（2 R）-2-磷酸甘油酸和α-吡喃酮，得到中间体，其通过除去磷酸和二氧化碳转化为大茎点霉酸。这些催化环加成前反应的酶也催化DA反应，即双功能酶。少

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 ProductsTautomycin 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 PhytotoxinsSeveral phytotoxins were isolated from phytopathogenic microorganisms in order to n … More 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 PhytotoxinsThe 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