第58届Intel ISEF中国参赛项目：夹竹桃叶提取物对菜青虫的杀虫成分分析及机理研究

卢湾高级中学  高三  杨立青

华师大二附中  高二  顾宇洲

上外浦东附中  高一 王肇欣

学科：植物学

    论文对夹竹桃（Nerium  indicum  Mill.）和白花夹竹桃（Nerium  indicum cv.Paihua ）叶的提取物对菜青虫的作用效果进行了初步研究。结果表明，夹竹桃叶的酒精提取物对菜青虫具有较强的触杀和拒食作用。
通过萃取，得到了含有杀虫成份的乙酸乙酯提取液，经过进一步浓缩干燥，获得了含有杀虫活性成分的褐色固体。用甲醇溶解此固体后，采用硅胶薄层层析法进行分离，确定杀虫活性成分的Rf值为0.75。
    通过HPLC分析发现其中14.311分出峰的组分具有杀虫活性。用安捷伦的LC/MS分析确定杀虫活性组分的分子量为598。
    论文对夹竹桃叶提取物的杀虫机理作初步的探讨。

Insecticidal Activity of Oleander Leaf Extract against Diamondback Moth and Identification of Its Active Constituent

Plant Sciences

Yang Liqing 18, Luwan Senior High School
Gu Yuzhou 17, No.2 Secondary School attached to East China Normal University
Wang Zhaoxin 16, Pudong Foreign Languages School, SISU

The study is to investigate a common plant in China, oleander, and its effect on diamondback moth (P. Xyloslella). Excessive chem-pesticides spraying leads to pests’ insecticide resistance and human’s health problems. Our study aims at identification, isolation and purification of insecticidal constituent of oleander biological activities of the two species of oleanders existed in Shanghai, Nerium indicum Mill (red flowers) and Nerium indicum cv. Paihua (white flowers), to isolate the active component. The insecticidal activity of ethanol extract from the 2 kinds of oleanders against the moth was tested. Our results indicated only Nerium indicum Mill leaf extract has potent repellent and contact-kill activity. Then, the ethanol extract was separated via various solvents. The active constituent was found dissolved in ethyl acetate. Thin-layer chromatography (silica gel TLC), via a comparison for the 2 species oleanders’ results, shown the component located at zone of Rf=0.75, which was fluorescent under UV. We utilized high performance liquid chromatography (HPLC) to further purify the active component. The LC combined mass spectrometry (LC-MS) determined constituent’s molecular weight is 576D. The nuclear magnetic resonance (NMR) demonstrated the molecular formula is C32H48O9. The mechanisms related to neurotoxic effect were also evaluated via polymerase chain reaction (PCR) of AchE. Finally the research institution evaluated its toxicity to mice, indicated it safe to vertebrate under the efficient pest-killing concentration of 94.2μg/10g. The result shows the active component of oleander leaves has a potential of becoming a novel class of bio-pesticides which is propitious to environmental protection. Future studies will focus on its long-term effect on eco-system, and its killing activity for other pests such as cabbage caterpillars.