Synthesis of p-hydroxycinnamic acid derivatives and investigation of fluorescence binding with bovine serum albumin

Four novel p-hydroxycinnamic acid amides, (E)-4-(3-oxo-3-((4-(N-(pyrimidin-2-yl)sulfamoyl)phenyl)amino)prop-1-en-1-yl)phenyl-acetate (SPPA), (E)-3-(4-hydroxyphenyl)–N-(4-(N-(pyrimidin-2-yl)sulfamoyl)phenyl)acrylamide (SPAA), (E)-4-(3-((4-(N-(4,6-dimethylpyrimidin-2-yl)sulfamoyl)phenyl)amino)-3-oxoprop-1-en-1-yl)phenyl acetate (SPOA), and (E)-N-(4-(N-(4,6-dimethylpyrimidin-2-yl)sulfamoyl)phenyl)-3-(4-hydroxyphenyl)acrylamide (SPHA), were synthesized. The chemical structures of these compounds were confirmed using 1H-NMR, ESI-MS, and elemental analyses. SPPA and SPOA were determined using single-crystal X-ray diffraction analysis. The interactions of these four compounds with bovine serum albumin (BSA) were investigated through fluorescence and UV–vis spectral studies. The thermodynamic parameters (i.e., ΔH, ΔG, and ΔS) and the quenching constants were calculated. The binding constants and the number of binding sites, n, were investigated. The distances between BSA and its derivatives were obtained based on fluorescence resonance energy transfer, and the conformational changes in BSA were observed from synchronous fluorescence spectra.