Interaction of cholinesterase modulators with DNA and their cytotoxic activity

This research was focused on a study of the binding properties of a series of cholinesterase reactivators compounds K075 (1), K027 (2) and inhibitors compounds K524, K009 and 7-MEOTA (3–5) with calf thymus DNA. The nature of the interactions between compounds 1–5 and DNA were studied using spectroscopic techniques (UV–vis, fluorescence spectroscopy and circular dichroism). The binding constants for complexes of cholinesterase modulators with DNA were determined from UV–vis spectroscopic titrations (K = 0.5 × 104–8.9 × 105 M−1). The ability of the prepared analogues to relax topoisomerase I was studied with electrophoretic techniques and it was proved that ligands 4 and 5 inhibited this enzyme at a concentration of 30 μM. The biological activity of the novel compounds was assessed through an examination of changes in cell cycle distribution, mitochondrial membrane potential and cellular viability. Inhibitors 3–5 exhibited a cytotoxic effect on HL-60 (human acute promyelocytic leukaemia) cell culture, demonstrated a tendency to affect mitochondrial physiology and viability, and also forced cells to accumulate in the G1/G0-phase of the cell cycle. The cholinesterase reactivators 1 and 2 were found relatively save from the point of view of DNA binding, whereas cholinesterase inhibitors 3–5 resulted as strong DNA binding agents that limit their plausible use.