Comparison of the antitumour effects and nephrotoxicity-inducing activities of two new platinum complexes, (-)-(R)-2-aminomethylpyrrolidine(1,1-cyclobutanedicarboxylato+ ++)-platinum (II) monohydrate, and its enantiomeric isomer

Abstract

New platinum complexes, (-)-(R)-2-aminomethylpyrrolidine(1,1- cyclobutanedicarboxylato)platinum(II) monohydrate (DWA2114R) and its enantiomeric isomer, (+)-(S)-2-aminomethylpyrrolidine(1,1- cyclobutanedicarboxylato)platinum(II) monohydrate (DWA2114S), were compared in their antitumour effects and nephrotoxicity-inducing activities. Both compounds were effective against the murine tumours L1210 and Colon 26 by i.p. injection of 20-100 mg kg-1. While DWA2114S showed marked increases in blood urea nitrogen (BUN) and urinary protein and sugar in BDF1 mice treated i.p. at the maximum tolerated dose, DWA2114R showed no increases in these parameters. To clarify the difference of nephrotoxicity between the isomers, tissue distribution was examined. Renal Pt concentration in DWA2114S-treated mice was more than 5-fold higher compared with that in DWA2114R-treated mice 2h after i.p. injection of 80 mg kg-1. However, there were no such marked differences in the lung, liver, heart, spleen and plasma. The low content of Pt in the kidneys of DWA2114R-treated mice could explain its lower nephrotoxicity. The in vitro experiments for uptake of the drugs into the cultured normal rat kidney cells and fresh splenocytes revealed that the Pt amount in the cells treated with DWA2114S, especially in the kidney cells, was much higher than DWA2114R.