Search for biologically active substances of plants by using the electrophysiological method with excitatory plant cells of Mimosa pudica

尽管外界对含羞草叶片在刺激下的运动已经有了较多的研究，而刺激的快速传导机制在含羞草中仍存在争议，但我们发现含羞草对外界物质的处理非常敏感，这种刺激会产生电生理反应。实际上，在观察静息电位时，通过施用其他植物的甲醇提取物记录了强脉冲。然后，我们以苦楝为例搜索导致这种活性的物质。C-和h - nmr，FT-IR和质谱分析，以及火焰分析的碱金属鉴定表明，分离的活性化合物为谷氨酸钠。虽然商业的l -谷氨酸钠在同样的实验中显示出同样强烈的脉冲，但非天然的d -谷氨酸钠根本没有这种脉冲。这明确表明，氨基酸与植物组织的相互作用在分子水平上是严格的非对映选择性的。从合欢素中分离到两种活性成分，其中一种鉴定为5-羟基果酸，另一种结构尚待确定。这些研究首次表明，测量M.pudica产生的电脉冲可以作为一种筛选植物界重要生物化合物的方法。

Although much attention has been paid on the leaf movement of Mimosa pudica with irritation and the mechanism for the rapid conduction of stimulus is still controversial in the plant, we found that M.pudica L.was very sensitve to the administration of extraneous substnces and such stimulation afforded electrophysiological responses. Actually, during observation of resting potential strong pulses wre recorded by an admistration of methanol extract of other plants. We then searched for the substance responsible for the activity in Melia azedarach L.as an example. ^<13>C- and ^1H-NMR,FT-IR and mass spectrometric analyzes, as well as alkaline metal identification by a flame analysis demonstrated that the isolated active compound was sodium glutamate. Although commercial L-sodium glutamate showed the same strong pulses in the identical assay, unnatural sodium D-glutamate did not afford such pulse at all. This unambiguously suggests that the interaction of the amino acid with the plant tissue was strictly diastereoselective at the molecular level. From Albizzia julibrissin, two compounds were isolated as active principles, one of which was identified as 5-hydroxypipecolic acid and other's structure still remains to be determined. These studies provide the first example to suggest that measuring the electric pulses produced by M.pudica could be utilized as a method for screening biologically important compounds in plant kingdom.