Quercetin solubilisation in bile salts: A comparison with sodium dodecyl sulphate

Abstract

To understand the bioaccessibility of the flavonoid quercetin we studied its interaction with bile salt micelles. The environmental sensitivity of quercetin's UV-visible absorption spectrum gave information about quercetin partitioning. Two quercetin absorption peaks gave complementary information: Peak A (240-280nm) on the intermicellar phase and Peak B (340-440nm) on the micellar phase. Thus, by altering pH, we showed that only non-ionised quercetin partitions into micelles. We validated our interpretation by studying quercetin's interaction with SDS micelles. Pyrene fluorescence and the quercetin UV-visible spectra show that the adsorption site for pyrene and quercetin in bile salt micelles is more hydrophobic than that for SDS micelles. Also, both quercetin and pyrene reported a higher critical micelle concentration for bile salts than for SDS. Our method of using a flavonoid as an intrinsic probe, is generally applicable to other lipophilic bioactives, whenever they have observable environmental dependent properties.

Keywords: Bioavailability; Micelles; Pyrene (PubChem CID: 104853); Pyrene fluorescence; Quercetin (PubChem CID: 5280804); Quercetin’s pK(a1); Sodium dodecyl sulphate (PubChem CID: 3423265); Sodium glycodeoxycholate (PubChem CID: 3035026); Sodium taurocholate (PubChem CID: 3035026); UV–visible spectra.