Spectrometric and voltammetric studies of the interaction between quercetin and bovine serum albumin using warfarin as site marker with the aid of chemometrics.
The interaction of quercetin, which is a bioflavonoid, with bovine serum albumin (BSA) was investigated under pseudo-physiological conditions by the application of UV-vis spectrometry, spectrofluorimetry and cyclic voltammetry (CV). These studies indicated a cooperative interaction between the quercetin-BSA complex and warfarin, which produced a ternary complex, quercetin-BSA-warfarin. It was found that both quercetin and warfarin were located in site I. However, the spectra of these three components overlapped and the chemometrics method - multivariate curve resolution-alternating least squares (MCR-ALS) was applied to resolve the spectra. The resolved spectra of quercetin-BSA and warfarin agreed well with their measured spectra, and importantly, the spectrum of the quercetin-BSA-warfarin complex was extracted. These results allowed the rationalization of the behaviour of the overlapping spectra. At lower concentrations ([warfarin]<1x10(-5) mol L(-1)), most of the site marker reacted with the quercetin-BSA, but free warfarin was present at higher concentrations. Interestingly, the ratio between quercetin-BSA and warfarin was found to be 1:2, suggesting a quercetin-BSA-(warfarin)(2) complex, and the estimated equilibrium constant was 1.4x10(11)M(-2). The results suggest that at low concentrations, warfarin binds at the high-affinity sites (HAS), while low-affinity binding sites (LAS) are occupied at higher concentrations.
Ni
Yongnian
Y
State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, Jiangxi 330047, China. ynni@ncu.edu.cn
Zhang
Xia
X
Kokot
Serge
S
D001665:Binding Sites / Q000187:drug effects; D015415:Biomarkers / Q000378:metabolism; D004347:Drug Interactions; D004563:Electrochemistry / Q000379:methods; D008954:Models, Biological; D008956:Models, Chemical; D009994:Osmolar Concentration; D011108:Polymers / Q000737:chemistry / Q000378:metabolism; D011794:Quercetin / Q000737:chemistry* / Q000378:metabolism; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D014859:Warfarin / Q000494:pharmacology*
D015415:Biomarkers; D011108:Polymers; D012710:Serum Albumin, Bovine; D014859:Warfarin; D011794:Quercetin