Intercalation of 2-butyl-4-methylphenol to G–C rich region of DNA and the role of hydroxypropyl-β-cyclodextrin

The characteristics of binding of 2-tert-butyl-4-methylphenol (TBMP), a synthetic phenolic antioxidant with hydroxypropyl-β-cyclodextrin (Hp-βCD) and calf thymus DNA (ctDNA) were investigated by multi-spectroscopic techniques and molecular simulation. The results indicated that TBMP preferred to form a 1:1 inclusion complex with Hp-βCD, with an inclusion constant of determined to be 7.15   ×   10 3   L   mol −1 . The intercalative mode of TBMP to ctDNA was supported by ctDNA melting temperature and relative viscosity studies, salt quenching effect, competitive binding with methylene blue and molecular modeling. The changes in Fourier transformed infrared (FT-IR) and circular dichroism (CD) spectra suggested that TBMP mainly bound to the G–C rich region with inducing a significant perturbation in B-like DNA structure. It was also found that Hp-βCD decreased the binding ability of TBMP with ctDNA, but did not affect the interactive mode between TBMP and ctDNA, and the formed inclusion complex of TBMP–Hp-βCD decomposed in the presence of ctDNA. This study may provide insights into the mechanism of binding of TBMP with ctDNA and the role of Hp-βCD in the TBMP–ctDNA interaction.