Astaxanthin binding affinity to DNA: Studied by fluorescence, surface plasmon resonance and molecular docking methods

Abstract

Abstract Astaxanthin (Ax), as a novel food supplement, a pink-red pigment, belongs to the carotenoid family. The study of DNA interactions with various drugs is very important for estimating the mechanism of interaction and developing new drugs. The purpose of this study is to investigate the binding affinity of Ax to double strand (ds) DNA evaluated by using a fluorescence spectroscopy, surface plasmon resonance (SPR) and docking approaches. The fluorescence results shown that Ax can quench the intensity amount of DNA fluorescence via a static quenching way. In the SPR method, DNA molecules were attached on a gold sensor surface. Using different amounts of ds DNA, the kinetic values KD, KA, and Ka were calculated. The obtained finding confirm that the binding of Ax to DNA has an exothermic and spontaneous mechanism. Also, thermodynamic studies were carried out using fluorescence analysis at four different temperatures, and the resulted negative data for ΔH and ΔS displayed that the main binding strength in the interaction of Ax to DNA was hydrogen bonding. Molecular docking results confirmed that the side chains of Ax interact specifically with base pairs and the DNA backbone.