Self-Association of Glycyrrhizic Acid. NMR Study

Abstract The use of various NMR techniques allows to demonstrate the aggregation processes of β-glycyrrhizic acid (GA) in water/methanol (4:1, v:v) mixture with solution pH≤5. The micelle formation was monitored by measuring T 2 relaxation and diffusion of GA. The model of gelation from micelles was suggested. It was shown that NMR chemical shifts of the protons of GA glucuronic moiety are sensitive to solution pH and not sensitive to GA concentration changes. At the same time the protons of triterpene moiety are sensitive to the nearest environment during the GA aggregation, and micelles are formed by hydrophobic interaction between the triterpene moieties of GA.