The Photode Gradation And Slow-Release Formulation Of Phenazine-1-Carboxylic Acid

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.