A comparative study of glycyrrhizin and glycyrrhetinic acid complexes interactions with DNA and RNA

Spectroscopic evidence showed that glycyrrhizin and glycyrrhetinic acid bind DNA and RNA via major and minor grooves as well as the backbone Glycyrrhetinic acid (GA), the main metabolic product of glycyrrhizin (GL) is an aqueous extract from licorice root. These compounds are well known for their anti-inflammatory, hepatocarcinogenesis, anti-viral and interferon (IFN)-inducing activity. This study is the first attempt to investigate the binding of glycyrrhizin and glycyrrhetinic acid with DNA and RNA. The effect of the ligand complexation on DNA and RNA aggregation and condensation was investigated in aqueous solution at physiological conditions, using constant DNA and RNA concentration (6.25 mM) and various ligands /polynucleotide (phosphate) ratios of 1/240, 1/120, 1/80, 1/40, 1/20, 1/10, 1/5, 1/2 and 1/1. Fourier transform infrared (FTIR) and UV–visible spectroscopic methods were used to determine the phosphate group with overall binding constants of KGL–DNA=5.7x103 M-1, KGA–DNA=5.1x103 M-1, KGL–RNA=3.03×103 M-1 and KGA–RNA=2.71×103 M-1. The affinity of ligands-DNA and -RNA binding is in the order of glycyrrhizin > glycyrrhetinic acid. DNA remains in the B-family and RNA remains in the A-family structures, while biopolymer aggregation occurred at high triterpenoid concentrations.