Gel electrophoresis and DNA interaction studies of the food colorant quinoline yellow

The interaction of native calf thymus DNA with the dye quinoline yellow (Sodium 2-(1,3-dioxoindan-2-yl) quinoline disulfonate) quinoline yellow (QY) has been investigated by absorption, emission, circular dichroism and viscosity and gel electrophoresis studies. Spectrophotometric studies of the interaction of QY with CT-DNA have shown that it can binds to CT-DNA and the CT-DNA binding constant (Kb = 6.2 ± 0.2 × 104 M−1) is comparable to groove binding dyes. Competitive fluorimetric studies with Hoechst 33258 have shown that QY exhibit the ability to displace the CT-DNA-bound Hoechst 33258 indicating that it binds to CT-DNA in strong competition with Hoechst 33258 for the groove binding. Furthermore, the QY induces detectable changes in the CD spectrum of CT-DNA as well as changes in its viscosity. Finally, all of the experimental results prove that the minor groove binding must be predominant. Gel electrophoresis study suggests that CT-DNA incubated with either QY did not show any significant CT-DNA cleavage.

► The use of synthetic colorants has been extensively increasing in the past two decades.
► There is evidence of conformation changes of DNA induced by its interaction with dye and drugs.
► We conclude that, the QY binds to DNA with a high affinity through a static mode.