Previous work in our laboratory investigated the ability of ammonium glycyrrhizinate (GLA) and two related compounds (carbenoxolone and glycyrrhetinic acid) to inhibit the DNA-binding properties HMGB1 in an in vitro screening system based on a quantitative capillary electrophoresis mobility shift assay (CEMSA). Our results demonstrated that GLA and GAK inhibited the DNA-binding of HMGB1 at concentrations above the critical micelle concentration. Thus, the inhibitory effects were observed only under conditions where the triterpenes formed aggregates and not when the compounds were in solution. Literature evidence suggests that compounds capable of forming aggregates inhibit or activate unrelated proteins including chymotrypsin, b-lactamse, b-galactosidase and alkaline phosphatase. The present work investigates the possible promiscuous nature of the inhibition of HMGB1/DNA interactions observed for GLA derivatives. The model proteins used in the study were glutathione Stransferase (GST) and alkaline phosphatase. Our results indicate that the GLA derivatives tested do not inhibit enzyme activity in the enzymes tested. On the contrary, GLA activated GST while GAK activated alkaline phosphatase. Taken together with our previous results, the present data suggest that GLA and GAK could be utilized in the inhibition of macromolecular interactions with minimal effects on cellular enzymes.
