Key Laboratory of Chemistry of Northwestern Plant Resources, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, People's Republic of China.
J Agric Food Chem. 2013 Jul 3;61(26):6321-7. doi: 10.1021/jf401241e. Epub 2013 Jun 20.
Trifolium pratense, a widespread legume forage plant, is reported to exhibit phytotoxic activity on other plants, but the active metabolites have not been clarified so far. A bioassay-guided fractionation of the root extracts led to the isolation of five isoflavonoids, which were elucidated by spectroscopic analysis. All of the purified compounds observably showed phytotoxic activities against Arabidopsis thaliana . Moreover, the inhibitory effects were concentration-dependent. The furan ring linked at C-4 and C-2' positions by an oxygen atom and a 1,3-dioxolane at C-4' and C-5' positions are considered to be critical factors for the phytotoxic activity. The concentrations of (6aR,11aR)-maackiain and (6aR,11aR)-trifolirhizin, concluded to be allelochemicals from soil around plants of T. pratense, were determined by HPLC and LC-MS to be 4.12 and 2.37 μg/g, respectively. These allelochemicals, which showed remarkable activities against the weed Poa annua may play an important role in assisting the widespread occurrence of T. pratense in nature.
红车轴草是一种广泛分布的豆科牧草植物，据报道对其他植物具有植物毒性活性，但到目前为止还没有明确其活性代谢物。对根提取物进行生物测定指导的分段分离导致分离出五种异黄酮，通过光谱分析阐明了它们的结构。所有纯化的化合物对拟南芥都表现出明显的植物毒性活性。此外，抑制作用呈浓度依赖性。呋喃环通过氧原子在 C-4 和 C-2' 位连接，在 C-4' 和 C-5' 位连接 1,3-二恶烷，被认为是植物毒性活性的关键因素。通过 HPLC 和 LC-MS 确定，（6aR,11aR）-马卡辛和（6aR,11aR）-三叶豆紫檀苷的浓度分别为 4.12 和 2.37μg/g，它们被认为是来自红车轴草根周围土壤的化感物质。这些化感物质对杂草草地早熟禾表现出显著的活性，可能在协助红车轴草在自然界中的广泛存在中发挥重要作用。
