Fig. 8. Displacement of DNA-bound Hoechst 33258 (H) by 5a (A), 5c (B), 5f (C), and 5m (D). Emission spectra (λex = 350 nm) of H (2.8 × 10–5 M) bound to CT-DNA (1 × 10–4 M, top line) and quenching of H–CT-DNA system by the compounds at increasing concentrations (0–2.2 × 10–5 M, curves from top to bottom). Insets: Fluorescence curves of EB bound to CT-DNA at λmax = 444 nm by 1,3,4-thiadiazole–chalcone compounds; r = [compound]/[CT-DNA]. The arrow shows that fluorescence intensity decreased with increasing concentration of the complex; representative fluorescence assay curves are shown. Triplicate assays were applied to all compounds and control CT-DNA.
