Polarographische Untersuchung cytostatischer Chinonderivate

Zusammenfassung

Bayer E 39 zeigt ein ungewöhnliches Polarogramm insofern, als es durch eine reversible Stufe (π_1/2=−0,23 V gegen NCE bei Ph 7) und eine besonders ausgesprochene katalytische Welle (π∼−1 V) charakterisiert ist. Das cytostatisch inaktive Produkt einer Hydrolyse von E 39 wird in einem Zwei-Elektronenschritt bei π_1/2=−0,45 V bei Ph 7 reduziert.

Summary

2,5-Bis-(ethyleneimino)-3,6-bis-(n-propoxy)-benzoquinone-(1,4) (Bayer E 39), a particularly remarkable member in the series of quinone derivatives exhibiting a cytostatic action, has been characterized polarographically. Its unusual polarogram is formed by a reversible step (π_1/2=−0,23 V against NCE at Ph 7) and a particularly distinct catalytic wave (π∼−1 V).

The two-electronic step which is likewise reversible yet not followed by a catalytic wave of the product of its hydrolysis 2,5-bis-(β-chloroethyleneamino)-3,6-bis-(n-propoxy)-benzoquinone-(1,4) (?) irreversibly formed in acid solution and which has lost the remarkable cytostatic activity of the initial substance, lies more negative by Δπ_1/2=−0,22 V at π_1/2=−0,45 V (Ph 7) which corresponds to a shifting of the absorption band of long wave length by Δ λ=60 mμ.

It is further to be noticed that, according to the electrophoretic and chromatographic studies of Ch. Scholtissek, the Ph-dependent reaction of Bayer E 39 (and A 139) with nucleic acids makes obvious that an interaction between the substrate and the cytostatically active quinones takes place in an acid medium only.