Complexes of 2,6-dihydroxybenzoic acid with divalent metal ions: Synthesis, crystal structure, spectral studies, and biological activity enhancement

摘要

2,6-Dihydroxybenzoic acid or gamma-resorcylic acid (DHBA) is a phenolic compound which is known to have poor biological performance such as DPPH scavenging activity and microbial growth inhibition. Combining DHBA with divalent metal ion to form complex is expected to improve its biological properties. The complexes of DHBA with divalent Ni/Co were synthesized and characterized in this study. The complex structures were determined by Xray single crystal analysis and it was found that metal interacted with DHBA through H-bonds. The results on the biological properties indicate that the complexes have remarkable DPPH scavenging activities and microbial growth inhibition abilities. IC0.5 value of DPPH is 35.68 mg/L (231.51 mu M), 9.21 mg/L (18.09 mu M) and 25.63 mg/L (50.33 mu M) for DHBA, NiDHBA and CoDHBA respectively. The microbial growth inhibitory value (%) at a sample concentration of 400 mg/L is 2.9, 6.4 and 96.1 against Escherichia coli and 4.9, 16.8, 98.2 against Staphylococcus aureus, for DHBA, NiDHBA and CoDHBA, respectively. (C) 2016 Elsevier B.V. All rights reserved.