Synthesis and Anti-Inflammatory and Antiulcer Activity of a Glycyrrhizic Acid Conjugate with L-Phenylalanine Methyl Ester

A conjugate of glycyrrhizic acid (GA) with L-phenylalanine methyl ester was synthesized using N-hydroxysuccinimide and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. Chemical modification of GA via addition of L-phenylalanine methyl ester moieties in the carbohydrate part of the glycoside was shown to form a marginally toxic compound with high anti-inflammatory activity in carrageenan- and formalin-induced mouse inflammation models and with pronounced antiulcer activity in rats. This was a significant advantage of this compound over known anti-inflammatory drugs.