Yang Yu-Zhang, Wei Qin-Ping, Zhou Jia, Li Min-Ji, Zhang Qiang, Li Xing-Liang, Zhou Bei-Bei, Zhang Jun-Ke
Institute of Forestry and Pomology, Beijing Academy of Agriculture and Forestry Sciences, Beijing, China.
Front Nutr. 2022 Apr 25;9:848857. doi: 10.3389/fnut.2022.848857. eCollection 2022.
The metallic complex is widely used in agricultural applications. Due to the oxidation of the metal and environmental unfriendliness of ligand, maintaining an efficient mineral supply for plants without causing environmental damage is difficult. Herein, an antioxidative trimetallic complex with high stability was synthesized by interacting Ca, Fe, and Zn with the biocompatible ligands from the Maillard reaction. The composite structure elucidation was carried out by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR). Thermal stability was measured by thermogravimetric (TG). Antioxidative activities were evaluated by ferric reducing antioxidant power and radical scavenging activity assays. The three metals were successfully fabricated on the Maillard reaction products (MRPs) with contents of Ca (9.01%), Fe (8.25%), and Zn (9.67%). Microscopy images revealed that the three metals were uniformly distributed on the MRPs with partial aggregation of <30 nm. FTIR and XPS results revealed that the metals were interacted with MRPs by metal-O and metal-N bonds. TG and antioxidative activity assays showed that the trimetallic complex meets the requirements of thermodynamics and oxidation resistance of horticultural applications. Additionally, the results of the exogenous spraying experiment showed that the trimetallic complex significantly increased the mineral contents of the "Fuji" apple. By treatment with the complex, the concentrations of Ca, Fe, and Zn were increased by 85.4, 532.5, and 931.1% in the leaf; 16.0, 225.2, and 468.6% in the peel; and 117.6, 217.9, and 19.5% in the flesh, respectively. The MRP-based complexes offered a higher growth rate of the mineral content in apples than ones based on sugars or amino acids. The results of the spraying experiment carried out in 2 years show that the method has high reproducibility. This study thus promotes the development of green metallic complexes and expands the scope of agrochemical strategy.
该金属配合物在农业应用中被广泛使用。由于金属的氧化以及配体对环境不友好，在不对环境造成破坏的情况下为植物维持高效的矿物质供应是困难的。在此，通过使钙、铁和锌与美拉德反应产生的生物相容性配体相互作用，合成了一种具有高稳定性的抗氧化三金属配合物。通过透射电子显微镜（TEM）、扫描电子显微镜（SEM）、X射线光电子能谱（XPS）和傅里叶变换红外光谱（FTIR）对复合结构进行了表征。通过热重分析（TG）测定热稳定性。通过铁还原抗氧化能力和自由基清除活性测定来评估抗氧化活性。三种金属成功地负载在美拉德反应产物（MRPs）上，钙（9.01%）、铁（8.25%）和锌（9.67%）的含量分别为这些值。显微镜图像显示，三种金属均匀分布在MRPs上，部分聚集体小于30纳米。FTIR和XPS结果表明，金属通过金属 - 氧键和金属 - 氮键与MRPs相互作用。TG和抗氧化活性测定表明，三金属配合物满足园艺应用的热力学和抗氧化性要求。此外，外源喷施实验结果表明，三金属配合物显著提高了“富士”苹果的矿物质含量。通过用该配合物处理，叶片中钙、铁和锌的浓度分别增加了85.4%、532.5%和931.1%；果皮中分别增加了16.0%、225.2%和468.6%；果肉中分别增加了117.6%、217.9%和19.5%。基于MRP的配合物使苹果中矿物质含量的增长率高于基于糖或氨基酸的配合物。在两年内进行的喷施实验结果表明该方法具有高重现性。因此，本研究促进了绿色金属配合物的发展，并扩大了农用化学品策略的范围。
