Graduate School of Agricultural Science, Kobe University, Nada, Kobe 657-8501, Japan.
Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Kagawa 761-0795, Japan.
Bioorg Med Chem. 2018 Aug 7;26(14):4225-4233. doi: 10.1016/j.bmc.2018.07.016. Epub 2018 Jul 10.
Reductive metabolism of strigolactones (SLs) in several plants was investigated. Analysis of aquaculture filtrates of cowpea and sorghum each fed with four stereoisomers of GR24, the most widely used synthetic SL, revealed stereospecific reduction of the double bond at C-3' and C-4' in the butenolide D-ring with preference for an unnatural 2'S configuration. The cowpea metabolite converted from 2'-epi-GR24 and the sorghum metabolite converted from ent-GR24 had the methyl group at C-4' in the trans configuration with the substituent at C-2', different from the cis configuration of the synthetic H-GR24 reduced with Pd/C catalyst. The plants also reduced the double bond in the D-ring of 5-deoxystrigol isomers with a similar preference. The metabolites and synthetic H-GR24 stereoisomers were much less active than were the GR24 stereoisomers in inducing seed germination of the root parasitic weeds Striga hermonthica, Orobanche crenata, and O. minor. These results provide additional evidence of the importance of the D-ring for bioactivity of SLs.
对几种植物中独脚金内酯（SLs）的还原代谢进行了研究。分析了分别用四种 GR24 立体异构体饲养的豇豆和高粱的养殖滤液，GR24 是最广泛使用的合成 SL，结果表明 D-环中 C-3'和 C-4'处的双键具有立体特异性还原，偏爱非天然的 2'S 构型。从 2'-表 GR24 转化而来的豇豆代谢物和从 ent-GR24 转化而来的高粱代谢物，C-4'上的甲基具有反式构型，与用 Pd/C 催化剂还原的合成 H-GR24 的顺式构型不同。这些植物还以类似的偏好还原了 5-去氧独脚金内酯异构体 D-环中的双键。代谢物和合成的 H-GR24 立体异构体的活性远低于 GR24 立体异构体，对根寄生杂草独脚金属、列当和欧氏列当的种子萌发的诱导作用较小。这些结果为 SLs 生物活性的 D-环的重要性提供了额外的证据。
