DNA minor groove binding of a well known anti-mycobacterial drug dapsone: A spectroscopic, viscometric and molecular docking study

Dapsone is a sulfone drug mainly used as anti-microbial and anti-inflammatory agent for the treatment of various diseases including leprosy. Recently, its interaction with protein (bovine serum albumin) is evidenced. But, the binding propensity of this anti-mycobacterial drug towards DNA is still unknown. Also, the mode of dapsone-DNA interaction (if any) is still an unknown quantity. In this study, we have taken a thorough attempt to understand these two unknown aspects using various biophysical and in silico molecular docking techniques. Both UV–visible and fluorescence titrimetric studies indicated that dapsone binds to CT-DNA with a binding constant in order of 104 M−1. Circular dichroism, thermal denaturation and viscosity experiments revealed that dapsone binds to the grooves of CT-DNA. Competitive DNA binding studies clearly indicated the minor groove binding property of this anti-mycobacterial drug. Molecular docking provided detailed information about the formation of hydrogen bonding in the dapsone-DNA complex. This in silico study further revealed that dapsone binds to the AT-rich region of the minor groove of DNA having a relative binding energy of −6.22 kcal mol−1. Overall, all these findings evolved from this study can be used for better understanding the medicinal importance of dapsone. •Dapsone binds to CT-DNA with a binding constant in order of 104 M−1.•Marginal change in Tm of CT-DNA in presence of dapsone hinted groove binding.•Viscometric and CD measurements also supported groove binding of dapsone to CT-DNA.•Competitive binding studies confirmed dapsone binds to the minor groove of CT-DNA.•Docking studies revealed the sites of DNA to which dapsone interacts.