Complex Formation of 2,3-Dihydroxybenzoic Acid and N-Acetylcysteine with Divalent Metal Ions: Solution Equilibrium, Synthesis, Characterization and Biological Activity Studies

• Main Authors: Shella Permatasari Santoso, 黎美清
• Other Authors: Yi-Hsu Ju
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/15565797628335710536

博士 === 國立臺灣科技大學 === 化學工程系 === 104 === Solution equilibriums of 2,3-dihydroxybenzoic acid, N-acetylcysteine and divalent transition metal ions (Mn2+, Co2+, Ni2+, Zn2+, Cu2+) were investigated in this study. The equilibrium constant values of binary and ternary compounds were determined by using potentiometric method at conditions similar to that of human physiology (37°C, ionic strength = 0.15 mol•dm-3 NaCl). The refinement of potentiometric data were done by using the Hyperquad 2008 computer program. The determination of equilibrium constants was confirmed by spectrophotometric method with refinement using the HypSpec program. The binary complexes of 2,3-dihydroxybenzoic acid were found to be more stable than that of N-acetylcysteine complexes. While in ternary systems, the combination of the two ligands resulted in synergistic effect, thus producing more stable complexes. Furthermore, 2,3-dihydroxybenzoic acid binary and ternary complexes including N-acetylcysteine were synthesized and characterized by analyses such as UV-Vis and IR. The synthesized complexes were found to improve biological properties of the original ligand especially in antimicrobial activity against Staphylococcus aureus and Escherichia coli. In all complexes synthesized, binary and ternary complexes of Zn2+ gave the best antimicrobial activity and were characterized further by elemental analysis and 1H NMR. From the results structures of the synthesized binary complex and ternary complex of Zn2+ were suggested. The binary complex was formed through the binding of 2,3-dihydroxybenzoic acid hydroxyl (—O) groups while the ternary complex was formed through the binding of the same groups of 2,3-dihydroxybenzoic acid as in the binary complex and the N-acetylcysteine carboxylic group (—COO) and thiol group (—S).