Spectroscopic Studies on the Interaction of Aloe-Emodin and DNA

Abstract

In this paper, DNA intercalation theory is introduced to study the interaction and the binding mode of aloe-emodin and DNA by fluorescence and resonance light scattering spectroscopy. Meanwhile, from the perspective of DNA intercalator we investigate pharmacological action of aloe-emodin and the effect of DNA and aloe-emodin on different conditions by spectrum methods. The work shows that the interactions of aloe-emodin and DNA result in the endogenous fluorescence quenching of aloe-emodin,which belongs to a static quenching mechanism. The binding constant and the binding site constant of the static quenching were calculated as 5.765 × 10² L mol and 0.7127. The result also indicates that four enhanced resonance light-scattering peaks appear at 240, 308, 468 and 557 nm, respectively. The resonance light-scattering peaks at 557 nm, which intensity enhances with the addition of DNA, was selected as investigation. This phenomenon were similar to ethidium bromide (EB) interaction of DNA, therefore aloe-emodin combines with DNA by intercalation. The interaction of aloe-emodin and DNA was influenced by different solution conditions. Resonance light-scattering intensity enhances on low pH value, sodium chloride, glucose and polar amino acids. Contrarily, nonpolar amino acids decrease the resonance light-scattering intensity. The alteration in environmental factors has a significant change in fluorescence intensity of aloe-emodin-DNA system. Therefore, the changing environmental factors can affect the interaction between aloe-emodin and DNA, so as to achieve the purposes of attenuation and synergistic effect.