Tumorhemmende Cyclopentadienylmetall-Komplexe: experimentelle Untersuchungen zur Überprüfung der Cyclopentadien-Hypothese

Abstract

Bis(cyclopentadienyl)metal(IV) diacido complexes (η 5-C 5H 5) 2MX 2 represent a recently developed group of cytostatic non-platinum-group metal complexes. Their cancerostatic activity clearly depends on the central atom M and, to a lesser extent, on the acido ligands X. Chemical modification of the cyclopentadienyl rings as well as the exchange of one of the C 5H 5 ligands result in a distinct reduction of antiproliferative activity. In the present study, the antitumor activity of aintraperitoneally applied cyclopentadiene C 5H 6 and dicyclopentadiene C 10H 12 was tested against fluid Ehrlich ascites tumor, proliferating in the peritoneal cavity, and against solid Ehrlich ascites tumor, growing subcutaneously in the nuchal region of mice. This was done to evaluate the conclusiveness of the “cyclopentadiene hypothesis” which ascribes the antitumor effectivity of metallocene complexes exclusively to cyclopentadiene released by hydrolytic cleavage of titanocene complexes. Whereas C 5H 6 and C 10H 12, administered locally into the fluid tumor, unfoled unspecific cytotoxic activity, they did not influence the growth of solid tumors. Thus, neither compound displays systemic tumor-inhibiting properties. So C 5H 6 and C 10H 12 cannot be assumed to be the intrinsically active species of cytostatic cyclopentadienylmetal complexes.