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 H₂-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 H₂-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.

研究了几种植物中草甘膦内酯（SLs）的还原代谢。对cow豆和高粱的水产养殖滤液分别添加了最广泛使用的合成SL GR24的四种立体异构体进行分析后，发现丁烯内酯D环的C-3'和C-4'处的双键立体定向还原，优先选择非自然的2 'S配置。豇豆代谢物从转换2'-外延-GR24和高粱代谢物从转换ENT -GR24'在有甲基基团在C-4反式构型的取代基的C-2'，从不同的顺式合成的结构高₂-GR24用Pd / C催化剂还原。植物也以类似的喜好还原了5-脱氧雌三醇异构体的D-环中的双键。代谢物和合成的H ₂ -GR24立体异构体在诱导根寄生杂草Striga hermonthica，Orobanche crenata和O. minor的种子萌发方面，比GR24立体异构体的活性低得多。这些结果提供了D环对于SL的生物活性的重要性的其他证据。