【作者】 郇庆文；

【导师】 彭华松；

【作者基本信息】 上海交通大学 ， 生物化工， 2011， 硕士

【摘要】 新型生物农药申嗪霉素,其有效成分为吩嗪-1-羧酸(phenazine-1-carboxylic acid, PCA),对甜椒疫病和西瓜枯萎病等有较好的防治效果。该农药具有广谱、低毒、低残留、与环境相容性好的特点,具有广阔的应用前景。但在生物防治过程中发现,PCA在大田中易被降解,影响其防治效果和推广使用。因此研究PCA的降解机理,并寻求延长防治效果的有效方式,是十分必要的。本论文主要研究PCA的光降解原理,并探究延长PCA防治效果的方式。本文首次研究了溶剂、光源种类、光照强度、溶液pH以及溶液中氧化剂对PCA光照稳定性的影响。并对PCA在可见光条件下的降解过程作了定量数学分析,发现PCA在水相中的降解符合一级动力学模型。在甲醇、丙酮、乙酸乙酯、pH 5.0缓冲液中的PCA经过可见光光照后,均发生降解,并且不同溶剂中的降解产物不同。以水作为溶剂时,紫外、太阳光和可见光光照后均能促使PCA发生降解,且降解产物的色谱保留时间一致。并且水溶液pH值越低,PCA越不稳定,PCA在pH 6.8溶液中的降解半衰期为37.6天,而当pH为5.0时,PCA的降解半衰期缩短至2.2天。在避光和可见光光照条件下,双氧水浓度越高,降解速率越快,且光照能明显加速PCA的降解速率。通过氮气除去溶液中的一定量的氧气后,PCA的光降解半衰期从原来的2.22天延长至4.30天。因此,为了提高PCA的稳定性,PCA更宜保存在避光、中性或碱性的环境中,且避免接触氧化性物质。HPLC检测发现PCA光降解后有两种新的降解产物出现,LC-MS和MSMS结果显示分子量分别为240和196。通过与纯品1-羟基吩嗪的HPLC和LC-MS的对照,确认物质B为1-羟基吩嗪,而物质A在1H和物质B结构的基础上,推测为6-羟基PCA或9-羟基PCA。因此,PCA降解反应的第一步为吩嗪环上的氧化,形成羟基PCA,并随后发生较彻底的裂解反应形成小分子。在应用方法的研究方面,借鉴了应用于医药的纳米材料,以改良农药剂型本身为切入点,从农药缓释剂型角度出发,运用AMS和HOM法合成纳米介孔二氧化硅,并通过硝酸氧化改性了纳米活性炭。通过对各种纳米材料进行载药和缓释实验,最后发现改性纳米活性炭的载药量目前可达0.3g/g (PCA/活性炭),并且具有较好的持续缓释效果,经过9次连续洗脱后,PCA的缓释效率达到55.67%。该PCA-改性纳米活性炭制剂具有一定的抑菌效果,具备开发前景。本论文首次对新型农药PCA的光照稳定性进行了系统分析,初步推测出PCA在可见光下的两个降解产物,为提高PCA的生物防治效果打下了理论基础。并首次对PCA-改性纳米活性炭农药新剂型进行了探索,研究提高生物农药在田间应用效力的方式,为新型农药PCA的应用奠定良好基础。更多还原

【Abstract】 Shenqinmycin, which key component is pheazine-1-carboxylic acid (PCA), is a promising bio-pesticide. However, it was found that PCA would be degraded easily in field and its protection efficiency was reduced. So it’s essential to study the mechanism of PCA degradation, or find an effective way to prolonging its biological effects.No reports concern its photochemical properties. Here the photostability of PCA under different conditions of solutions, light sources, photon flux density, pH value and oxidants was investigated systematically and the degradation kinetic model was also established for the first time. Under irradiation of visible light, PCA can be degraded with different products in methanol, acetone, ethyl acetate and pH 5.0 PBS. In aqueous solution, PCA was degraded under the irradiation of UV, visible and sun light with same products, and the degradation exhibited light-dependent behavior. The degradation of PCA followed first-order reaction kinetic under visible light. The degradation rate constant (k) increased with the increased photo flux density and higher concentration of H~+. During pH 5.0-8.0 study, the half-life of PCA upon exposure to visible light was just 2.2 days at pH 5.0, But it jumped to 37.6 days at pH 6.8. The oxidants, H2O2 and dissolved O2, can also accelerate the photodegradation of PCA. When O2 was removed from its solution, the half-life of PCA increased to 4.30 days from 2.22 days. Moreover, two products (A and B) were detected and determined by HPLC, LC-MS, MSMS and NMR. Product B was 1-Hydroxyphenazine. Product A was deduced as 1-carboxylic acid-6-hydroxyphenazine or 1-carboxylic acid-9-hydroxyphenazine. So the first step of PCA degradation was deduced as the oxidation reaction, then product A was degraded into small molecules.For new applications, the‘slow-release formulation’was synthesized according to clinical research of drug and pesticide improvement. The nanophase material of silicon dioxide was synthesized by AMS and HOM methods, and the nano-active carbon was also modified by nitrate. The modified active carbon had good adsorption efficiency and release rate. The current loading-capacity was 0.3g/g (PCA/Active carbon), and release rate was 55.67%.This is the first report to study the PCA photo degradation and almost determined two new products. And this is also the first report to study the synthesis of slow release PCA- active carbon formulations.更多还原