Characterizing the binding of tert-butylhydroquinone and its oxidation product tert-butylquinone with calf thymus DNA in vitro

Abstract The binding characteristics of food antioxidant tert-butylhydroquinone (TBHQ) and its oxidation product tert-butylquinone (TBQ) with calf thymus DNA (ctDNA) in vitro were investigated using multispectroscopy, chemometrics, viscosity measurements, gel electrophoresis assays and molecular docking. Analysis of fluorescence spectra found that TBHQ and TBQ bound with ctDNA to form 1:1 complexes with the binding constant in the order of 104 L mol−1. The concentration profiles and the pure spectra for the components (TBHQ, TBQ, ctDNA and TBHQ– or TBQ–ctDNA complex) were obtained through analyzing the expanded ultraviolet-visible absorption data matrix by multivariate curve resolution–alternating least squares algorithm, which successfully monitored the binding process of TBHQ/TBQ with ctDNA. Fluorescence displacement, viscosity and molecular docking experiments showed that TBHQ bound to ctDNA through intercalation binding, while TBQ bound to the minor groove of ctDNA. The binding of TBHQ to ctDNA induced the conversion of DNA conformation from B-form to A-form, while TBQ caused a minor perturbation on the DNA conformation. Gel electrophoresis results indicated that the combination of TBHQ and Cu(II) could induce DNA damage. This study may contribute to understanding the binding mechanisms of TBHQ and TBQ with ctDNA and further evaluate the potential toxicological effects of TBHQ as a food additive.