New Fe(iii) and Co(ii) salen complexes with pendant distamycins: selective targeting of cancer cells by DNA damage and mitochondrial pathways.

Minor groove binding distamycin like moieties were conjugated with core salens and the corresponding Fe(iii) and Co(ii) complexes were synthesized. Herein, we have shown efficient DNA minor groove binding specificities along with excellent DNA cleavage capacities with metallosalen conjugates. The metal complexes showed toxicity toward various cancer cells over normal cells with high specificity. Interestingly, the Co(ii) complexes exhibited greater activity than the Fe(iii) complexes in accordance with the stronger affinity of the former in the biophysical studies. Active DNA damage, and prominent nuclear condensation along with the release of cytochrome-c from the mitochondria unanimously showed that the metal complexes followed apoptotic pathways to induce cell death.