Synthesis and biothermokinetic study of a new Schiff base and its bismuth(III) complex on the growth metabolism of S. pombe and H. pylori cell lines

In this study, a new Schiff base ligand [2-{[4-amino-5-(3,4,5-trimethoxy-benzyl)-pyrimidin-2-ylimino]-methyl}-6-methoxy-phenol, C22H24N4O5] and its bismuth(III) complex [BiC22H22N4O5Cl] were synthesized using o-vanillin and trimethoprim in anhydrous solvents. Chemical analysis, elemental analysis, spectrum analysis and TG–DSC analysis were employed to characterize the compositions and structures of the two new compounds. In particular, the metabolic thermogenic curves of Schizosaccharomyces pombe (S. pombe) and Helicobacter pylori (H. pylori) cells treated by the two new compounds at different concentrations were monitored by an isothermal microcalorimeter at 32.00 and 37.00 °C, respectively. On the basis of the metabolic thermogenic curves, some important biothermokinetic parameters such as the microbial growth rate constant (k), inhibition ratio (I) and half inhibition concentration (IC50) were estimated. The experimental results indicated that both the Schiff base ligand and its bismuth(III) complex could inhibit the growth metabolism of S. pombe and H. pylori, but the inhibitory abilities of the two compounds were as follows: the Schiff base ligand > the complex for S. pombe and the Schiff base ligand < the complex for H. pylori, respectively. More importantly, the results also found that the Schiff base bismuth(III) complex exhibited bidirectional biological effect and hormesis effect on H. pylori cell line, i.e., the complex can stimulate the growth metabolism of H. pylori at low concentration, while inhibiting its growth at high concentration.