Interactions of the baicalin and baicalein with bilayer lipid membranes investigated by cyclic voltammetry and UV-Vis spectroscopy

The baicalin and baicalein are the major flavonoids found in Radix Scutellariae, an essential herb in traditional Chinese medicine for thousands of years. The interactions of the baicalin and baicalein with lipid bilayer membranes were studied using cyclic voltammetry and UV-Vis spectroscopy. The thickness d of supported bilayer lipid membranes was calculated as d = 4.59(+/- 036) nm using AC impedance spectroscopy. The baicalein interacted with egg PC bilayer membranes in a dose-dependent manner. The responses of K3Fe(CN)(6) on lipid bilayer membrane modified Pt electrode linearly increased in a concentration range of baicalein from 6.25 mu M to 25 mu M with a detection limit of 0.1 mu M and current-concentration sensitivity of 0.11(+/- 0.01) mu A/mu M, and then reached a plateau from 25 mu M to 50 mu M. However the baicalin showed much weaker interactions with egg PC bilayer membranes. UV-Vis spectroscopy also confirmed that the baicalein could interact with egg PC membranes noticeably, but the interaction of baicalin with membranes was hard to be detected. The results provide useful information on understanding the mechanism of action of Radix Scutellariae in vivo. (C) 2013 Elsevier B.V. All rights reserved.