Antibacterial Properties of a Kind of Schiff Base and Its Neodymium(III) and Zn(II) Complex (ZnNdL) on Escherichia coli

Abstract

AbstractThe microcalorimetric and electronic microscopy methods were used to study the antibacterial activity of a Schiff base and its complex ZnNdL on Escherichia coli. The metabolic power‐time curves of the bacteria treated with the compounds were obtained, and the thermokinetic parameters were analyzed. The results show that the compounds (H2L, ZnNdL) have good activity on aerobic multiplying metabolism of E. coli, with the values of IC50 57.0 and 54.4 mg·L−1, respectively. In order to further investigate their mechanism on E. coli, transmission electronic microscopy and scanning electronic micrography were used to study the cell membrane change induced by the dibasic quadridentate Schiff base and its neodymium(III) complex. At a low concentration of the compound, the flagellum was inhibited and the cell did not show distinct changes. However, the flagella around the cell membrane were exfoliated, the morphology of E. coli was changed from a rod shape into a spherical shape or a short rod, and the flagella disappeared completely at a high concentration. The drug permeability into cell membrane was investigated by fluorescence quenching of probe dis‐C3‐(5), which suggested that H2L and ZnNdL could influence on the intra and extra cell membrane.