AUTHOR=Yang Yu-zhang , Wei Qin-ping , Zhou Jia , Li Min-ji , Zhang Qiang , Li Xing-liang , Zhou Bei-bei , Zhang Jun-ke 

TITLE=Nano-Sized Antioxidative Trimetallic Complex Based on Maillard Reaction Improves the Mineral Nutrients of Apple (Malus domestica Borkh.)

JOURNAL=Frontiers in Nutrition

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.848857

DOI=10.3389/fnut.2022.848857

ISSN=2296-861X

ABSTRACT=Metallic complex is widely used in agricultural applications. Because of the oxidation of 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 synthesised by interacting Ca2+, Fe2+, and Zn2+ with the biocompatible ligands from Maillard reaction. The composite structure elucidation was carried out by TEM, SEM, XPS, and FTIR. Thermal stability was measured by 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 the trimetallic complex meet the requirements of thermodynamics and oxidation resistance of horticultural applications. Additionally, the results of exogenous spraying experiment showed that the trimetallic complex significantly increased the mineral contents of ‘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 MRPs-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 two 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.