Biochemical Studies on Relationships between Plant Fungitoxins and Phytopathogens

对羽扇豆（Lupinus albus和L. luteus）的组成异黄酮进行了研究，发现其含有大量的简单和复杂的异黄酮和香豆素，其中许多具有真菌毒性。罗苹异黄酮的结构变化主要是由以下五个因素引起的：1)基本结构（4种简单的异黄酮）2)在6和/或3'(L上戊烯基（=3,3-二甲基烯丙基）取代。3)丙烯基侧链的修饰（水化、末端羟基化和转化为2-羟基-3-甲基-3-丁烯基）4)环的形成（二氢呋喃、二氢吡喃和吡喃融合的A-和/或b环）5- o-甲基化（L. luteus）人们早就认识到一些真菌具有代谢和解毒异黄酮的能力，在某些情况下，这一过程似乎与致病性密切相关。研究发现灰霉病菌可以将戊烯基化异黄酮转化为各种二氢呋喃异黄酮和二氢吡喃异黄酮以及乙二醇，这些异黄酮都可能通过在适当的底物中不饱和侧链的环氧化而产生。在非手性异黄酮转化为手性异黄酮的过程中，真菌代谢产生的极性化合物的底物特异性大大降低了真菌毒性和立体化学。进一步的实验证实了环氧化物作为一种代谢中间体的存在，从丙烯化异黄酮到环醚和乙二醇衍生物。结果表明，该环氧化合物以灰孢杆菌和5,2',4'-三羟基-7甲氧基-8-戊烯基异黄酮为底物，得到了预期的环氧化合物。对大鼠肝脏匀浆中5,7,2',4'-四羟基-6-戊烯异黄酮（叶黄酮）代谢的比较生物化学兴趣也进行了研究。

As the results of the present study on constitutive isoflavonoids in lupins (Lupinus albus and L. luteus) were found to contain numerous simple and complex isoflavones and coumaronochromones, many of which were fungitoxic. The structural variation in the lupin isoflavonoids are due to the following five factors:1) basic structure (4 kinds of simple isoflavonoids)2) prenyl (=3,3-dimethylallyl) substitution at 6 and/or 3'(L. albus) and at 6 or 8 (L. luteus)3) modification of the prenyl sidechain (hydration, terminal hydroxylation and transformation to 2-hydroxy-3-methyl-3-butenyl group)4) ring formation (dihydrofurano-, dihydropyrano- and pyrano-fused A- and/or B-ring5) 5-O-methylation (L. luteus)It has long been recognized that some fungi have the ability to metabolise and detoxify isoflavonoids, and in certain cases this process seems to be closely linked with pathogenicity. Botrytis cinerea was found to convert prenylated isoflavones into various dihydrofurano- and dihydropyrano-isoflavones, and glycols, all of which might arise via epoxidation of the unsaturated sidechain in the appropriate substrate. The substrate specificity of the fungal metabolism yielding those polar compounds with greatly decreased fungitoxicity and stereochemistry in the metabolism of an achiral isoflavone to a chiral one been elucidated.A further experiment was conducted to confirm the presence of an epoxide as a metabolic intermediate from a prenylated isoflavone to cyclic ether and glycol derivatives. The expected epoxide was successfully detected by using B. cinerea and 5,2',4'-trihydroxy-7 methoxy-8-prenylisoflavone as a substrate.The fate of 5,7,2',4'-tetrahydroxy-6-prenylisoflavone (luteone) in rat liver homogenates was also examined from the interest in comparative biochemistry of the prenylated isoflavone metabolism.