Microcalorimetric Study of Tetrahymena Growth Affected by Copper(II) Complexes

By means of microcalorimetry, the effect of four copper(II) complexes on Tetrahymena growth was investigated. The extent and duration of the inhibitory effect on the metabolism, judged by the rate constant, k, and the half inhibition concentration, IC50, varied with the different complexes. The results showed that the half inhibition concentrations IC50 of CuCl2, (C9H6NO)2Cu and [Cu(phen)2]Cl2⋅6H2O were 9.9 × 10−4, 2.0 × 10−4, and 2.6 × 10−4 mol/L, respectively. The sequence of antibiotic activity of these three complexes was: (C9H6NO)2Cu > [Cu(phen)2]Cl2⋅6H2O > CuCl2. The growth rate constants of [Cu(phen)3]Cl2⋅6H2O did not change obviously with the increase of concentrations, but [Cu(phen)3]Cl2⋅6H2O also can prolong the time of Tetrahymena growth.