Pedras M S, Okanga F I
Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan S7N 5C9, Canada.
J Agric Food Chem. 1999 Mar;47(3):1196-202. doi: 10.1021/jf980854r.
The remarkable metabolism of the cruciferous phytoalexin cyclobrassinin by the phytopathogenic root rot (Rhizoctonia solani Kuhn) and blackleg [Phoma lingam (Tode ex Fr.) Desm., asexual stage of Leptosphaeria maculans (Desm.) Ces. et de Not.] fungi is reported. It was established that R. solani metabolized and detoxified cyclobrassinin via the phytoalexin brassicanal A, which was further transformed into nontoxic products. Detoxification of cyclobrassinin in P. lingam avirulent isolate Unity occurred via the phytoalexin brassilexin, whereas the detoxification in P. lingam virulent isolate BJ 125 occurred via the phytoalexin dioxibrassinin. The chemistry involved in the structure determination of the intermediates of these three apparently different pathways and their antifungal activities are described. In addition, efficient syntheses of both phytoalexins brassicanal A and brassilexin by mimicry of the fungal biotransformation route are reported. Implications of these unprecedented transformations are discussed.
据报道，植物致病根腐病菌（立枯丝核菌库恩）和黑胫病菌[十字花科黑斑病菌（托德原弗氏菌）德姆，大斑壳二孢菌（德姆）切斯和德诺特的无性阶段]对十字花科植物抗毒素环布西菌素具有显著的代谢作用。已确定立枯丝核菌通过植物抗毒素芸苔醛A代谢并解毒环布西菌素，芸苔醛A进一步转化为无毒产物。十字花科黑斑病菌无毒分离株“统一”对环布西菌素的解毒作用通过植物抗毒素油菜素发生，而十字花科黑斑病菌有毒分离株BJ 125对环布西菌素的解毒作用则通过植物抗毒素二氧芸苔素发生。描述了这三种明显不同途径的中间体结构测定所涉及的化学过程及其抗真菌活性。此外，还报道了通过模拟真菌生物转化途径高效合成植物抗毒素芸苔醛A和油菜素。讨论了这些前所未有的转化的意义。
