Specific interaction of chalcone‐protein: Cardamonin binding site II on the human serum albumin molecule

Abstract

Cardamonin (2',4'-dihydroxy-6'-methoxychalcone), one of the main constituents from the seeds of Alpinia katsumadai Hayata, belongs to chalcone with its antibacterial, antiinflammatory and other important therapeutic activities of significant potency and low systemic toxicity. In this article, the interaction of cardamonin to human serum albumin (HSA) has been studied for the first time by spectroscopic methods including Fourier transform infrared (FTIR) spectroscopy, circular dichroism (CD), and UV-absorption spectroscopy in combination with fluorescence quenching under physiological conditions with drug concentrations of 0.67-4.0 microM. The results of the spectroscopic measurements and the thermodynamic parameters obtained (the enthalpy change DeltaH(0) and the entropy change DeltaS(0) were calculated to be -25.312 and 7.040 J.mol(-1).K(-1) according to the van't Hoff equation) suggest that hydrophobic interaction is the predominant intermolecular forces stabilizing the complex, which is also in good agreement with the results of the molecule modeling study. The alterations of protein secondary structure in the presence of cardamonin in aqueous solution were quantitatively calculated by the evidence from CD and FTIR spectroscopes with reductions of alpha-helices of about 20%, decreases of beta-sheet structures of about 14%, and increases of beta-turn structures of about 15%. The quenching mechanism and the number of binding sites (n approximately 1) were obtained by fluorescence titration data. Fluorescent displacement measurements confirmed that cardamonin binds HSA on site II. In addition, the effects of common ions on the constants of the cardamonin-HSA complex were also discussed.

Molecular interaction of human serum albumin with paracetamol: Spectroscopic and molecular modeling studies

“…6 shows the CD spectra of HSA without and with paracetamol. The CD spectra of HSA exhibited two distinct negative minima at 208 and 220 nm, which are the typical signals of the helix structure [32]. The addition of paracetamol into HSA solution resulted in a decrease in the ellipticity indicating that the binding of paracetamol to HSA induced the conformational changes in the protein, which is consistent with the fluorescence results.…”

Interaction Between 2′,4-Dihydroxychalcone and the N, F, E Conformers of Bovine Serum Albumin: Influence of Temperature and Ionic Strength

“…The obtained binding constants fell in the range of 1.954 9 10 5 -3.192 9 10 7 , exhibiting similar values to those obtained for the BSA complexation with warfarin and flavonoids [9], indicating an intermediate affinity [17].…”

Comparison of the characterization on binding of alpinetin and cardamonin to lysozyme by spectroscopic methods

“…Medicinally, plants of this family are reputed to have values as antihepatotoxic, anti-inflammatory, and stomachic properties [10]. In previous works [11,12], we reported optical spectroscopic studies to characterize the interaction of active components in Chinese herbs with human serum albumin (HSA), yet the investigation on binding interaction of alpinetin and cardamonin to LYSO have not been reported. A new enzymatic assays and analyses are presented in the paper.…”