Investigation of the biological activities of licorice root (Glycyrrhiza glabra) and its bioactive component Glycirizine

Glycyrrhiza glabra (G. glabra, Licorice), belonging to the Fabaceae family, is one of the worldwide known medicinal plants due to its various biological and pharmacological properties. Its important bioactive component, glycyrrhizin, is widely used in herbal medicine and food industry. For this reason, it was aimed to determine the antimicrobial and cytotoxic activity of the root extract of G. glabra and its bioactive component, glycyrrhizin. For this purpose, firstly, the G. glabra sample obtained from Hatay Province was extracted with ethanol for 8 hours by using a soxhlet apparatus. Secondly, the chemical composition of the obtained extract was determined using Gas Chromatography Mass Spectroscopy (GC-MS). Third, the antimicrobial activity of G. glabra extract and its bioactive component, glycyrrhizin, were tested against Gram-positive (Streptococcus mutans ATCC®35668, Staphylococcus aureus ATCC®25923, Bacillus cereus ATCC®7064, Bacillus subtilis ATCC®6633, Listeria monocytogenes ATCC®7677), Gram-negative (Klebsiella pneumoniae ATCC®700603, Escherichia coli ATCC®25922, Salmonella Enteritidis ATCC®13076, Citrobacter freundii ATCC®43864, Pseudomonas aeruginosa ATCC®27853) bacteria and yeast (Candida albicans ATCC®10231) using well diffusion and microdilution methods. Finally, the cytotoxic activity of G. glabra extract and glycyrrhizin was determined by MTT method. According to the GC-MS results, 28 components were identified in the chemical content of the G. glabra plant. The pharmacologically important components with the highest % area was determined as 2,8-Dimethyl-7,8-dihydro-6H-cyclohepta (18.59) and Thiophene (16.58). According to the antimicrobial activity results, it was determined that the G. glabra extract had a significant antimicrobial activity on Gram-positive bacteria L. monocytogens (20,66 ±1,15) and S. mutans (19.66±1.52, 125 µg/mL). S. Enteritidis (16.66 ± 0.57, 500 µg/mL) was found to be the most effective among Gram-negative bacteria. According to MTT results, G. glabra extract showed cytotoxic effect on human liver carcinoma (Hep G2) cell line, and its IC50 value was 250 µg/mL and glycyrrhizin was 50 µM. The results of this study showed that G. glabra may have the potential to be used for alternative purposes, supported by In vivo studies.