title: Interactions between antimalarial indolone-N-oxide derivatives and human serum albumin.
abstract: The binding affinity of human serum albumin (HSA) to three antimalarial indolone-N-oxide derivatives, INODs, was investigated under simulated physiological conditions using fluorescence spectroscopy in combination with UV-vis absorption and circular dichroism (CD) spectroscopy. Analysis of fluorescence quenching data of HSA by these compounds at different temperatures using Stern-Volmer and Lineweaver-Burk methods revealed the formation of a ground state indolone-HSA complex with binding affinities of the order 10(4) M(-1). The thermodynamic parameters ΔG, ΔH, and ΔS, calculated at different temperatures, indicated that the binding reaction was endothermic and hydrophobic interactions play a major role in this association. The conformational changes of HSA were investigated qualitatively using synchronous fluorescence and quantitatively using CD. Site marker competitive experiments showed that the binding process took place primarily at site I (subdomain IIA) of HSA. The number of binding sites and the apparent binding constants were also studied in the presence of different ions.
authors.affiliation: Université de Toulouse 3, UPS, UMR 152 (Laboratoire de pharmacochimie des substances naturelles et pharmacophores redox), F-31062 Toulouse cedex 9, France.
authors.forename: Nehal
authors.initials: N
authors.lastname: Ibrahim
authors.forename: Hany
authors.initials: H
authors.lastname: Ibrahim
authors.forename: Sothea
authors.initials: S
authors.lastname: Kim
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Nallet
authors.forename: Françoise
authors.initials: F
authors.lastname: Nepveu
mesh_terms: D000962:Antimalarials / Q000737:chemistry*; D001665:Binding Sites; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007211:Indoles / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D012709:Serum Albumin / Q000737:chemistry*; D013057:Spectrum Analysis; D013816:Thermodynamics
chemical_list: D000962:Antimalarials; D007211:Indoles; D012709:Serum Albumin