Abstract
Purpose:
Flavonoids are the most common polyphenolic compounds in fruits and vegetables. These pigments may have important pharmacological relevance in prevention of eye disease. It has been reported that flavonoids such as resveratrol could inhibit vascular endothelial growth factor (VEGF) secretion and prevent neovascularization, a major complication in age-related macular degeneration (AMD). Flavonoids also have possible anti-cancer, anti-inflammatory, and anti-oxidant properties. Though polar compounds, these relatively hydrophobic molecules are poorly soluble in water, suggesting the role of a blood transport protein in their delivery to the target tissues.
Methods:
In this study, we assess the binding interactions of flavonoids with human serum albumin (HSA), the most abundant protein in the blood, and with glutathione S transferase pi isoform-1 (GSTP-1), an enzyme with well characterized hydrophobic binding sites that plays an important role in detoxification of xenobiotics with reduced glutathione, using a novel Taylor dispersion surface plasmon resonance (SPR) technique.
Results:
For the first time, HSA sites revealed a high-affinity binding site for flavonoid interactions. Out of the four flavonoids that we examined, quercetin and kaempferol showed the strongest equilibrium binding affinities (KD) of 63 ± 0.03 nM and 37 ± 0.07 nM, respectively. GSTP1 showed lower affinities in the micromolar range towards all of the flavonoids tested.
Conclusions:
The interactions of flavonoids with HSA and GSTP1 were studied successfully using the new SPR assay method. The new method proved to be an efficient technique to explore the full analyte dose-response in biomolecular interactions using a single injection. It could increase sample throughput and data content and at the same time decrease sample preparation time. Binding parameter estimation is important in understanding the associated biological pathways of these flavonoids.