Interactions of lamotrigine with single- and double-stranded DNA under physiological conditions

This study presents evaluation of the possible mechanisms of interaction between the antiepileptic drug lamotrigine (LMT) and single- and double-stranded DNA (ssDNA and dsDNA, respectively). These interactions were studied in phosphate-buffered saline (PBS) at physiological pH 7.4 by cyclic voltammetry (CV) and square wave voltammetry (SWV) using a glassy carbon electrode (GCE) in a bulk incubated solution. The addition of both types of DNA to LMT solution decreased peak currents and led to a negative shift in peak potentials, thus indicating the dominance of electrostatic interactions. UV-Vis absorption spectroscopy was also used to assess the interaction between ds/ssDNA and LMT. The data obtained from spectroscopic analysis confirmed that electrostatic interaction is the predominant interaction between LMT and both types of DNA. The calculated binding constants for LMT-dsDNA and LMT-ssDNA complexes as determined by SWV were 6.46 × 10⁵ and 1.81 × 10⁶, respectively, while the values obtained from UV-Vis spectroscopy were 6.93 × 10⁵ and 1.19 × 10⁶, respectively. The obtained results indicated a higher affinity of LMT for ssDNA than for dsDNA.