Influence of glycyrrhizin on permeability and elasticity of cell membrane: perspectives for drugs delivery

Glycyrrhizin or glycyrrhizic acid (GA) - triterpene glycoside extracted from licorice root - has been intensively studied over the past decade and is considered to be a potential drug delivery system. Glycyrrhizin was found to enhance the therapeutic effect of various drugs; however the detailed mechanism of these effects is still unknown and attracts the attention of researchers. In this work, we have made an attempt to clarify the mechanism of Glycyrrhizin activity on molecular and cellular level. The influence of GA on the functional properties of biomembranes was investigated via NMR spectroscopy and atomic force microscopy (AFM) using human erythrocytes as a model system. GA was shown to increase the permeability (about 60%) and to decrease elasticity modulus of cell membranes (by an order of magnitude) even in micromolar concentrations. Changes on the erythrocyte surface were also detected by AFM. These results could provide a new insight on the mechanism of bioavailability enhancement of some drugs in the presence of glycyrrhizin, as well as the mechanism of its own biological activity. The role of cholesterol-glycyrrhizin binding in the observed effects is also discussed.