Study of antibacterial effects of dexamethasone drug, in vitro and in silico analysis of its binding to DNA

Dexamethasone (Dex), a drug with anti-inflammatory effects, is widely used worldwide. Therefore this study aimed to investigate the effect of the drug on DNA and some flora bacterial strains. Effect of Dex on DNA breakages was analyzed by treating of supercoiled plasmid DNA with Dex and then analysis on agarose gel electrophoresis. The analysis was repeated at the presence of iron, hydrogen peroxide, ascorbic acid, iron plus hydrogen peroxide, copper and copper plus ascorbic acid. In addition, the drug-DNA interactions were studied using UV-Vis spectrophotometer and in-silico methods. Effect of the drug on some flora bacterial strains was investigated by disc diffusion and broth dilution methods. In this in-vitro study, the drug did not break the supercoiled DNA at any concentrations even at higher concentrations (1700, 170, 17, 1,7 and 0,42 µM) than those found in human plasma. The effect of Dex on DNA did not change in the presence of Asc, H2O2, iron and copper. Binding constant of the drug with DNA was obtained as 7256 1/M. In-silico analysis showed bonding of the drug on a minor groove of double helix DNA by the binding energy of almost -5.84, making 3 hydrogen bonds and hydrophobic bonds. 2264 µM of the drug increased colony forming units (CFU) of E. cloacae, E. coli, E. faecalis and P. mirabilis by 10 %, 23 %, 42 % and 10 % respectively. Also, 1132 µM of the drug cause to increase CFU of E. coli and E. faecalis by 30 % and 19 % respectively. In conclusion, dexamethasone causes an increase in some of the flora bacteria while it does not show any effect on DNA in in-vitro condition