Interaction of sulforaphane with DNA and RNA.

Sulforaphane (SFN) is an isothiocyanate found in cruciferous vegetables with anti-inflammatory, anti-oxidant and anti-cancer activities. However, the antioxidant and anticancer mechanism of sulforaphane is not well understood. In the present research, we reported binding modes, binding constants and stability of SFN-DNA and -RNA complexes by Fourier transform infrared (FTIR) and UV-Visible spectroscopic methods. Spectroscopic evidence showed DNA intercalation with some degree of groove binding. SFN binds minor and major grooves of DNA and backbone phosphate (PO2), while RNA binding is through G, U, A bases with some degree of SFN-phosphate (PO2) interaction. Overall binding constants were estimated to be K(SFN-DNA)=3.01 (± 0.035)×10(4) M(-1) and K(SFN-RNA)= 6.63 (±0.042)×10(3) M(-1). At high SFN concentration (SFN/RNA = 1/1), DNA conformation changed from B to A occurred, while RNA remained in A-family structure

Intensity ratio variations for several DNA and RNA in-plane vibrations as a function of SFN concentration.

<p>(A) Intensity ratios for DNA bands at 1714 (G, T), 1665 (T, G, A, C), 1610 (A), 1490 (C,G) and 1226 (PO2 asymmetric) referenced to the DNA band at 966 cm^-1. (B) Intensity ratios for the RNA bands at 1697 (G, U), 1650 (U, G, A, C), 1610 (A), 1488 (C,G) and 1241 (PO2 asymmetric) referenced to the RNA band at 969 cm^-1.</p

Docking structure between (PDB 3CZW) and SFN.

<p>(A) Surface representation of (PDB 3CZW) complexes with SFN (Display side). (A') Close up view of (PDB 3CZW) complexes with SFN. (B) Surface representation of (PDB 3CZW) complexes with SFN (Display top).</p

FTIR spectra in the region of 1800–800 cm^-1 for sulforaphane (SFN), calf thymus DNA (A) and yeast RNA adducts (B) in aqueous solution at pH = 7.

<p>DNA or RNA and two complexes spectra were obtained at various SFN/DNA and-RNA (phosphate) molar ratios (three two spectra); sulforaphane and two difference spectra (bottom three spectra).</p

Docking structure between (PDB 2R22) and SFN.

<p>(A) Surface representation of (PDB 2R22) complexes with SFN (Display side). (A') Close up view of (PDB 2R22) complexes with SFN. (B) Surface representation of (PDB 2R22) complexes with SFN (Display top).</p

Docking structure between d(CGCGAATTCGCG) (PDB 1BNA-DNA) and SFN.

<p>(A) Surface representation of d(CGCGAATTCGCG) complexes with SFN (Display side). (A') Close up view of d(CGCGAATTCGCG) complexes with SFN. (B) Surface representation of d(CGCGAATTCGCG) complexes with SFN (Display top).</p

Chemical structure of sulforaphane (SFN).

<p>Chemical structure of sulforaphane (SFN).</p

Ultraviolet–visible results of SFN and calf thymus DNA and its Complexes (A), and yeast RNA and its complex (B): (1) SFN–DNA and SFN–RNA complexes; (2) free DNA or free RNA (0.5 mM); (3) free SFN (0.5 mM).

<p>Plot of 1/(A-A₀) versus (1/drug concentration) for SFN and calf thymus DNA complexes (A^'), and plot of 1/(A-A₀) versus (1/drug concentration) for SFN and yeast RNA complexes (B^'), where A₀ is the initial absorbance of DNA (259 nm) or RNA at (258 nm) and A is the recorded absorbance at different SFN concentrations (5×10^–6–1×10^–4 M) with constant DNA or RNA concentrations of 0.5 mM at pH 7.</p