β-Glycyrrhetinic acid inhibits the bacterial growth and biofilm formation by supragingival plaque commensals

A review of typical biological activities of glycyrrhetinic acid and its derivatives

Glycyrrhetinic acid, a triterpenoid compound primarily sourced from licorice root, exhibits noteworthy biological attributes, including anti-inflammatory, anti-tumor, antibacterial, antiviral, and antioxidant effects. Despite these commendable effects, its further advancement and application, especially in clinical use, have been hindered by its limited druggability, including challenges such as low solubility and bioavailability. To enhance its biological activity and pharmaceutical efficacy, numerous research studies focus on the structural modification, associated biological activity data, and underlying mechanisms of glycyrrhetinic acid and its derivatives. This review endeavors to systematically compile and organize glycyrrhetinic acid derivatives that have demonstrated outstanding biological activities over the preceding decade, delineating their molecular structures, biological effects, underlying mechanisms, and future prospects for assisting researchers in finding and designing novel glycyrrhetinic acid derivatives, foster the exploration of structure-activity relationships, and aid in the screening of potential candidate compounds.

Pharmacological Features of 18β-Glycyrrhetinic Acid: A Pentacyclic Triterpenoid of Therapeutic Potential

Glycyrrhiza glabra L. (belonging to the family Leguminosae), commonly known as Licorice, is a popular medicinal plant that has been used in traditional medicine worldwide for its ethnopharmacological efficacy in treating several ailments. Natural herbal substances with strong biological activity have recently received much attention. The main metabolite of glycyrrhizic acid is 18β-glycyrrhetinic acid (18βGA), a pentacyclic triterpene. A major active plant component derived from licorice root, 18βGA has sparked a lot of attention due to its pharmacological properties. The current review thoroughly examines the literature on 18βGA, a major active plant component obtained from Glycyrrhiza glabra L. The current work provides insight into the pharmacological activities of 18βGA and the potential mechanisms of action involved. The plant contains a variety of phytoconstituents such as 18βGA, which has a variety of biological effects including antiasthmatic, hepatoprotective, anticancer, nephroprotective, antidiabetic, antileishmanial, antiviral, antibacterial, antipsoriasis, antiosteoporosis, antiepileptic, antiarrhythmic, and anti-inflammatory, and is also useful in the management of pulmonary arterial hypertension, antipsychotic-induced hyperprolactinemia, and cerebral ischemia. This review examines research on the pharmacological characteristics of 18βGA throughout recent decades to demonstrate its therapeutic potential and any gaps that may exist, presenting possibilities for future drug research and development.

Synergistic inhibitory activity of Glycyrrhizae Radix and Rubi Fructus extracts on biofilm formation of Streptococcus mutans

BACKGROUND

Streptococcus mutans is a bacterium that causes oral diseases. Plaque, a biofilm produced by S. mutans and other bacteria, makes it difficult to remove cariogenic oral microorganisms, including biofilm producers. Glucan synthesis by glucosyltransferase is one of the mechanisms underlying plaque formation. This study demonstrates the effectiveness of inhibiting biofilm formation by interfering with the glucosyltransferase activity of S. mutans using edible herbal medicines.

METHODS

This study investigated the inhibitory activity of Glycyrrhizae Radix extract, Rubi Fructus extract, glycyrrhizin from Glycyrrhizae Radix, and ellagic acid from Rubi Fructus against glucosyltransferase activity of S. mutans. Enzyme kinetic analysis identified the mechanism by which glycyrrhizin and ellagic acid inhibit enzyme activity.

RESULTS

The conditions for synergistically inhibiting biofilm formation by combining Glycyrrhizae Radix and Rubi Fructus extracts were identified. Biofilm formation was also synergistically inhibited by mixing their respective active constituents, glycyrrhizin and ellagic acid. Glycyrrhizin and ellagic acid inhibited glucosyltransferase via noncompetitive and uncompetitive mechanisms, respectively, indicating that they inhibit it via distinct mechanisms.

CONCLUSIONS

This study presents an effective oral hygiene method using the synergistic activity of two natural plant extracts to inhibit biofilm formation through different inhibitory mechanisms against glucosyltransferase of S. mutans.

Antibacterial activity of 18β-glycyrrhetinic acid against Neisseria gonorrhoeae in vitro

Gonorrhea is the second most common sexually transmitted diseases worldwide. Chronic infection of Neisseria gonorrhoeae (N. gonorrhoeae) can lead to severe complications. Presently, N. gonorrhoeae has developed resistance to almost all antibiotics used for the treatment of gonorrhea. Thus, it's urgent to explore new approaches to treat gonorrhea. Presently, nontraditional treatment method as an alternative to antibiotic use is getting more and more attention. Here we demonstrated that 18β-glycyrrhetinic acid (GRA) exhibited robust antimicrobial activity against N. gonorrhoeae in vitro. GRA led to a significant decline in viable N. gonorrhoeae in a dose dependent manner compared with DMSO treatment (P < 0.001). Addition of GRA resulted in a significant reduction in viable bacteria within 2 h post-inoculation (P < 0.001). Minimum inhibitory concentrations (MICs) to GRA ranged from 3.9 to 62.5 μg/ml overall, with MIC50 and MIC90 values of 31.25 μg/ml and 62.5 μg/ml, respectively. There was no significant difference of MIC 50 and MIC90 between multi-drug resistant (MDR) strains and non-MDR strains. Minimum bactericidal concentration (MBC) ranges were 3.9-125 μg/ml, basically consistent with MIC values. GRA inhibited biofilm formation and diminished pre-formed biofilm. These data suggested that GRA could be a candidate for gonorrhea treatment.