Synthesis, in vitro antiplasmodial and antiproliferative activities of a series of quinoline–ferrocene hybrids

Abstract

Series of quinoline–ferrocene hybrids containing various linkers were synthesized and evaluated for antimalarial and anticancer activities as well as cytotoxicity. The hybrids with rigid linkers were found to be inactive, while those with flexible spacers showed activity against both the D10 and Dd2 strains of Plasmodium falciparum, and demonstrated a good selectivity towards these parasitic cells in comparison with emetine. The hybrid 16, featuring 3-aminopropyl methylamine linker, was the most antimalarial active compound, exhibiting a significantly better potency than chloroquine against the Dd2 strain (IC50 = 0.008 vs. 0.148 μM; 19-fold), and was also found to be significantly more active than the equimolar chloroquine–ferrocene combination (IC50 = 3.7 vs. 41 ng/ml, tenfold) against the Dd2 strain. Anticancer activity screening showed that all the antimalarial active hybrids also exhibited potent cytostatic (GI50 = 0.6–3.3 μM) and had good cytotoxic effects (LC50 = 6–8 μM) against all three cancer cell lines. The hybrid 11 possessing 1,4-butanediamine linker was distinctively the most antiproliferative of all. It was found to be more cytostatic (GI50: 0.7 vs. 5.9 μM, eightfold) and (LC50: 6.4 vs. 92.6 μM, 14-fold) more cytotoxic than etoposide against the TK10 (renal) cell line.