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Issue 4, 2007
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Binding and photochemistry of enantiomeric 2-(3-benzoylphenyl)propionic acid (ketoprofen) in the human serum albumin environment

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Abstract

Global analysis of circular dichroism multiwavelength data and time resolved fluorescence was applied to investigate the interaction of R(–)- and S(+)-ketoprofen (KP) with human serum albumin (HSA) in buffer solution at neutral pH. The most stable drug:protein adducts of 1 : 1 and 2 : 1 stoichiometry were characterized as regards the stability constants and the absolute circular dichroism spectra. The spectra of the diastereomeric 1 : 1 conjugates are negative with minima at ca. 350 nm for R(–)-KP and 330 nm for S(+)-KP, those of the 2 : 1 complexes are both negative with minimum at 340 nm and quite similar in shape to each other, thereby showing that the protein loses chiral recognition capability upon multiple binding. HSA intrinsic time resolved fluorescence data obtained exciting at 295 nm point to Trp 214 being located in the secondary binding site for both KPenantiomers. The photodegradation of the S(+)- and R(–)-KP:HSA complexes was studied by steady state photolysis using λirr > 320 nm. No decrease of the photodegradationquantum yields was observed in 1 : 1 complexes. An induction time for the photodegradation course in 2 : 1 complexes was observed. Transient absorption spectroscopy at λexc = 355 nm showed that triplet KP species were formed with stereo-differentiated lifetimes and high quantum yields (0.7–0.9). Secondary transients were consistent with the occurrence of photodecarboxylation and/or photoreduction within the protein matrix.

Graphical abstract: Binding and photochemistry of enantiomeric 2-(3-benzoylphenyl)propionic acid (ketoprofen) in the human serum albumin environment

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Article information


Submitted
29 Sep 2006
Accepted
15 Nov 2006
First published
12 Dec 2006

Photochem. Photobiol. Sci., 2007,6, 462-470
Article type
Paper

Binding and photochemistry of enantiomeric 2-(3-benzoylphenyl)propionic acid (ketoprofen) in the human serum albumin environment

S. Monti, I. Manet, F. Manoli and S. Sortino, Photochem. Photobiol. Sci., 2007, 6, 462
DOI: 10.1039/B614163C

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