A multi-spectroscopic approach to investigate the interaction of prodigiosin with ct-DNA

• PG intercalated into the DNA helix.
• The binding of PG and ct-DNA are partial intercalation mode.
• Van der Waals forces are mainly between PG and ct-DNA in the present of EB.
• The interaction follows the static quenching mechanism.

The interaction between prodigiosin (PG) and calf thymus DNA (ct-DNA) was investigated firstly by using UV–Visible (UV–Vis), fluorescence, Fourier transform infrared (FT-IR), circular dichroism (CD) spectroscopies and viscosity measurement in Tris–HCl buffer solution (pH 6.8). The experimental results indicated that PG intercalated into the DNA helix. Upon addition of ct-DNA, PG showed hypochromic effect and slight redshift in the absorption spectra, and the melting temperature of ct-DNA was increased by from 58 to 64 °C. Furthermore, FT-IR spectrum and CD spectra also suggested that the partial bases of ct-DNA react with prodigiosin. The fluorescence quenching mechanism was studied using ethidium bromide as a DNA probe, The binding constants of PG with ct-DNA in the presence of EB are 4.46 × 104 and 2.32 × 104 M−1 at 298 and 310 K, respectively, and the corresponding thermodynamic parameters ΔG, ΔH, ΔS at various temperatures were obtained.

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