Interaction of calf thymus DNA with the antiviral drug Lamivudine.

One approach to accelerate the availability of new cancer drugs is to test drugs approved for other conditions as anticancer agents. In recent years, some researchers have shown that antiviral drugs, such as ritonavir, saquinavir, and nelfinavir, inhibit the growth of over 60 cancer cell lines derived from nine different tumor types. This article studied the anticancer potential of an antiviral drug, lamivudine (LA). The interaction of LA and calf thymus DNA (CT-DNA) was studied using emission, absorption, circular dichroism (CD), and viscosity techniques. The binding constants evaluated from fluorescence data at different temperatures revealed that fluorescence enhancement is a static process that involves complex-DNA formation in the ground state. Further, the enthalpy and entropy of the reaction between the drug and CT-DNA showed ΔH<0 (-126.38±0.61 kJ mol(-1)) and ΔS<0 (-352.17±2.1 J mol(-1) K(-1)); therefore, van der Waals interactions or hydrogen bonds are the main forces in the binding of LA to CT-DNA. The values of K(f) clearly underscore the high affinity of LA to DNA. In addition, detectable changes in the CD spectrum of CT-DNA in the presence of LA indicated conformational changes. All these results showed that groove binding is the binding mode of this drug and CT-DNA.