Synthesis of Glycyrrhizic Acid Conjugates with Amino-Acid Methyl Esters and their Ability to Stimulate Antibody Genesis in Mice

Conjugates of glycyrrhizic acid (GA) with methyl esters of L-amino acids (valine, methionine, and glutamic acid) containing the amino-acid residues in the carbohydrate moiety of the glycoside were synthesized using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. The resulting GA conjugates at a dose of 2 mg/kg stimulated a primary immune response (production of antibody-forming cells, AFCs) in outbred mice by 1.6 - 3 times as compared with the control. The conjugate of GA with Glu(OMe)₂ stimulated antibody genesis in outbred mice 1.7 times more efficiently than N-acetylmuramyl dipeptide and showed a stimulating effect on AFC production in the spleen of CBA mice.