Effect of verapamil on <em>Enterococcus faecalis</em>, <em>Escherichia coli </em>and on DNA damage induced by copper and iron

Abstract

Verapamil is commonly used oral drug for treatment of high blood pressure and heart diseases worldwide. Here, we investigated the effect of verapamil on two of human intestinal flora bacterial strains Enterococcus faecalis and Escherichia coli using the broth medium dilution method and agar disc diffusion method. In addition, DNA was treated with verapamil, verapamil plus H2O2, verapamil plus ascorbic acid, verapamil plus iron and verapamil plus copper and analyzed by agarose gel electrophoresis. The interaction of verapamil with DNA was investigated by UV-Vis spectrophotometer and in silico methods. Verapamil inhibited the growth of both E. faecalis and E. coli up to 90% at concentrations of 9, 18 and 25 mM. The concentration of 9 mM (480 mg dose) of the drug was found as both MIC and MBC value for the two bacterial strains. The drug did not show any breaking or protective effect on the supercoiled plasmid DNA. In the UV-Vis spectrophotometer analysis, verapamil did not show any interaction with the DNA. In contrast, in silico analysis showed the drug to bind to a minor groove of double helix DNA by hydrogen bonds and hydrophobic interactions with the binding energy of 7.3 kcal/mol and binding constant (Kb) value of 2.3×105 M-1.