The biothermochemical characteristics of the actions of Y , TMP and their cationic monoporphyrinate complex |[Y(TMP)(H2O)3]Cl, TMP= 5,10, 15,20-tetrakis(4'-methoxyphenyl)porphyrin| on growth metabolism of Staphylococcus aureus were studied by means of a LKB-2277 Bioactivity Monitor at 37.00 ℃. The growth rate constants k_1, k_2 inhibiting ratio I( %), the total heat effect (Q_(total)) and half inhibition of concentration IC50 (mg· L~(-1)), respectively were obtained. Experimental results show that Y~(3+) and [Y(TMP) (H_2O)_3]C1 have the duplex biological effection: they stimulate the growth of the Staphylococcus aureus at lower concentration but inhibit the growth at high concentration. Inhibitory effection of Y~(3+) , TMP and [Y(TMP) (H_2O)_3]Cl is [Y(TMP)(H_2O)_3]C1> TMP>Y~(3+).

Key words: YTTRIUM COMPOUNDS, PORPHYRIN, STAPHYLOCOCCUS ARUEUS, THERMODYNAMICS, DEPRESSING