Chemicals Constituents of the Algerian Glycyrrhiza glabra L. Root Extracts and their Antioxidant, Antibacterial and Anticholinesterase Activities

Abstract

Background: Glycyrrhiza glabra L. is an important medicinal plant endowed with various pharmacological virtues. This study aimed to investigate the antioxidant, antibacterial, and anticholinesterase activities of the Algerian Glycyrrhiza glabra L. roots extracts. Methods: The chemical composition of both chloroformic (LCh) and ethyl acetate (LAE) extracts were analyzed by RP-HPLC-PDA and 1H NMR spectroscopy. The antioxidant activity was evaluated using hydrogen atoms transfer methods (DPPH) and single electron transfer (ABTS and CUPRAC assays). The antibacterial activity was realized against different strains via the Minimal Inhibitory Concentration (MIC), when the anticholinesterase activity was performed through the acetylcholinesterase and butyrylcholinesterase enzymes inhibition. Results: The chemical analysis revealed the presence of phenolic acids (gallic acid, p-coumaric acid) and a hydroxycinnamic compound (ferulic acid). However, flavonoids were represented by quercetin, rutin (flavonol), and glabridin (isoflavane). The 1H NMR of the L4 fraction from LCh extract allowed to characterize the structure of glabridin. The antioxidant assays revealed that LCh extract is the best among other extracts with IC50 DPPH of 33.94 μg/mL, IC50 ABTS of 3.45 μg/mL and CUPRAC A0.5 of 21.78 μg/mL. The LCh extract displayed an effective antibacterial activity with MIC’s of 19.5 μg/mL against seven gram positive and negative bacteria strains. The same extract showed a potent butyrylcholinesterase inhibitory activity with IC50= 4.72 ± 0.72 μg/mL, which is too strong than the standard drug. Conclusion: The study demonstrated that G. glabra root extracts had a high antibacterial, and free radical scavenging. It was also able to inhibit cholinesterase enzymes, which confirm the effectiveness of phytoconstituents present in the plant, especially flavonoids.