Abstract
Background: Glycyrrhizic Acid (GA) is the major triterpene saponin of licorice roots. The
most important derivative of GA is its monoammonium salt (glycyram, GC). Some pharmacological
properties of triterpene saponins explain their molecular complexation with Cholesterol (Chol). However,
the molecular complexation of GC with Chol has not been proven. The functional groups of GA
and GC involved in the interactions with Chol were not identified.
Methods: The complexation has been investigated by the method of isomolar series in the spectrophotometric
version, IR, and 13C NMR spectroscopy. The constant is calculated on the basis of isomolar
curves.
Results: The molecular complex of GC with Chol has been prepared for the first time. It has been
shown that GC forms a 1 : 1 complex with Chol having a stability constant Ks of (3.3 ± 0.2)×105
(mol/L)-1 (in 70% aqueous EtOH at 18 °С).
Conclusion: Intermolecular interaction in the complex is carried out by hydrogen bond formation between
C=O group of GC (in carboxyl group of the terminal residue of glucuronic acid in the carbohydrate
part) and 3β-hydroxyl group of Chol: -С=О⋅⋅⋅Н-О-. Hydrophobic contacts of the aglycone part of
GC with a lipophilic Chol molecule are possible.
Keywords:
Molecular complex, glycyrrhizic acid, monoammonium glycyrrhizinate, cholesterol, licorice, saponins.
Graphical Abstract
[2]
Tolstikov, G.A.; Baltina, L.A.; Grankina, V.P.; Kondratenko, R.M.; Tolstikova, T.G. Licorice: Biodiversity, chemistry, and application in medicine In: Geo: Novosibirsk; , 2007.
[13]
Yakovishin, L.A.; Grishkovets, V.I. Ivy and Licorice Triterpene Glycosides: Promising Molecular Containers for Some Drugs and Biomolecules. Studies in Natural Products Chemistry; Atta-ur-Rahman; Elsevier, B.V., Ed.; Amsterdam, 2018, Vol. 55, pp. 351-383.
[19]
Yakovishin, L.A.; Grishkovets, V.I. Molecular complexes of ivy triterpene glycosides with cholesterol. Khimiya Rastitel’nogo Syr’ya, 2018, 4, 133-140.
[29]
Moghimipour, E.; Kooshapour, H.; Rezaee, S.; Khalili, S.; Handali, S. In vitro cholesterol binding affinity of total saponin extracted from Glycyrrhiza glabra. Asian J. Pharm. Clin. Res., 2014, 7(1), 170-173.
[31]
Polyakov, N.E.; Leshina, T.V. NMR relaxation study of cholesterol binding with plant metabolites. Appl. Magn. Reson., 2011, 41(2), 283-294.
[32]
Gluschenko, O.Yu.; Polyakov, N.E.; Leshina, T.V. NMR study of cholesterol complexes with glycyrrhizic acid. Magn. Reson. Solids, 2011, 13(2), 5-9.
[35]
Babko, A.K. Physico-chemical analysis of complex compounds in the solutions; Izd-vo AN USSR: Kiev, 1955.
[39]
Hobza, P.; Zagradnik, R. Intermolecular complexes; Academia: Prague, 1989.
[40]
Kalinin, V.I.; Levin, V.S.; Stonik, V.A. The chemical morphology: triterpene glycosides of sea cucumbers (Holothurioidea, Echinodermata); Dalnauka: Vladivostok, 1994.