Inhibition of the Specific Binding of 12-O-Tetradecanoylphorbol-13-Acetate to Mouse Epidermal Membrane Fractions by Glycyrrhetic Acid

Abstract

Glycyrrhetic acid inhibited the specific binding of 12–O–tetradecanoylphorbol-13-acetate (TPA) to mouse epidermal membrane fractions in a dose- and time-dependent manner. Glycyrrhizic acid, a glycoside of glycyrrhetic acid, has no inhibitory effect on TPA binding. The results of kinetic analysis suggested that glycyrrhetic acid directly binds to the TPA receptor, resulting in the competitive inhibition of the binding of TPA to its receptor without affecting the number of binding sites (Ki = 2.2 x 10^-4M). The inhibitory effect of glycyrrhetic acid on TPA binding to the membrane receptor may play a role in its antitumor-promoting activity in vivo.