Synthesis And Antibacterial Activities Research Of N-o-Hydroxybenzyl-Substiturted Amino Acid Metal Conplexes

At present, infectious diseases occurre frequently in the world, and the demand of disinfection pharmaceutical surges. But the lack of efficient and safe microbicide seriously restricts the development of infectious disease control medicine. In order to seek efficient, stable and low-toxic antibacterial agents, early in our group, we combined the " halogenated o-hydroxy benzyl" to the amino acids and their esters with strong biological activity to synthesize various of N-(halogenated o-hydroxy benzyl) amino acids and their esters and tested their antibacterial effects. Study confirmed that these compounds had strong inhibition against bacteria and fungi.On this basis, the reaction conditions of pre-screening N-(5-chloro-2-hydroxy benzyl) amino acid ester schiff base which had good antimicrobial activity were optimized in this paper. And we synthesized 18 kinds of N-( halogenated o-hydroxybenzyl) amino acids / esters and their schiff bases as ligands, and selected human-essential metals such as copper, cobalt, iron and manganese, to design and synthesize 72 kinds of metal complexes and tested their antibacterial activity.Two N-(5-chloro-2-hydroxybenzyl) amino acid ester schiff bases were designed and synthesized with chlorinated salicylaldehyde and L-amino acid ester as raw materials by alkali-catalyzed condensation reaction of schiff base, and then were reduced by sodium borohydride. With 5-Br salicylaldehyde and L-amino acids / esters as raw materials by the method mentioned above, we synthesized 8 kinds of N-(5-bromo-2-hydroxybenzyl) amino acids / esters and their schiff bases. With 3,5-dibromo salicylaldehyde and L-amino acid / ester as raw materials, 4 kinds of N-(3,5-dibromo-2-hydroxy benzyl) amino acids / esters and their schiff bases were synthesized. Using 1H NMR, IR, the structures of the compounds were confirmed.Complexes were synthesized by step-by-step method with N-(halogenated o-hydroxy benzyl) amino acids / ester derivatives and four kinds of metal ions as materials, in alkaline solution of water and methanol mixed solvents at room temperature, and the molar ratio of ligand and metal ion was 1:1. The colors of the complexes were relavent to the metal ions. Single crystal X-ray diffraction showed that the phenol hydroxyl, carboxyl and amino of ligands were combined to metal iron. The antibacterial activity of such complexes showed that almost all the complexes had better antibacteria property than their ligands, especially to the Monilia albicans with 100% inhibitory ratio.And the fact that amion acid complexes had batter activity than the amion acid ester complexes told us that water-soluble played an important role in antibacteria property.