The licorice pentacyclic triterpenoid component 18β-glycyrrhetinic acid enhances the activity of antibiotics against strains of methicillin-resistant Staphylococcus aureus

Study on the correlation between Flavobacterium columnare infection and gill injury in Largemouth bass (Micropterus salmoides) and the protective effect of Enoxolone

Columnaris disease, caused by Flavobacterium columnare, has a broad host range and can afflict multiple families and genera of freshwater fish. In addition, our prior research found that Enoxolone emerged as the most promising candidate with a low minimum inhibitory concentration and good cost-effectiveness. However, the therapeutic effect of Enoxolone on Micropterus salmoides infected with F. columnare remains unclear, and its antibacterial efficiency in vivo has yet to be investigated. In this study, we found that the cumulative mortality rate of M. salmoides reached 70 % within 96 h post-infection with 1 × 108 CFU/mL F. columnare, and the gills exhibited clinical signs such as paleness and ischemia, accompanied by characteristic "Clavate Gill" pathological changes. Meanwhile, both the severity of these lesions and the bacterial load showed a significantly upward trend over time. In addition, following Enoxolone treatment, the mortality rate of M. salmoides infected by F. columnare was reduced by 40 %, with alleviated general pathological changes and a significantly lower number of apoptotic positive cells compared to the infected but untreated group. The relative expression of apoptosis and inflammation-related genes showed that the expression levels of Caspase-9, IL-18, TNF-α and NF-κB were significantly upregulated after F. columnare infection. However, the relative expression of Bcl-2 and IL-10 was significantly upregulated after treatment with Enoxolone. In conclusion, there was a positive correlation between the F. columnare load and gill damage in M. salmoides. In addition, Enoxolone has potential therapeutic and protective effects against gill tissue damage caused by F. columnare. Presumably, this efficacy may stem from the drug's ability to inhibit bacteria, thereby reducing gill cell apoptosis and inflammation. These findings provide new perspectives for future research and establish a groundwork for devising preventive and curative strategies against F. columnare infections.

Identification of TonB-dependent siderophore receptor inhibitors against Flavobacterium columnare using a structure-based high-throughput virtual screening method

TonB-dependent siderophore receptors play a critical transport role for Flavobacterium columnare virulence formation and growth, and have become valuable targets for the development of novel antimicrobial agents. Traditional Chinese medicine has demonstrated notable efficacy in the treatment of fish diseases and includes potential antibacterial agents. Herein, we performed molecular docking-based virtual screening to discover novel TonB-dependent siderophore receptor inhibitors from traditional Chinese medicine and provide information for developing novel antibacterial agents. Firstly, we efficiently obtained 11 potential inhibitors with desirable drug-like characteristics from thousands of compounds in the TCM library based on virtual screening and property prediction. The antibacterial activity of Enoxolone, along with its interaction characteristics, were determined via an MIC assay and molecular dynamic simulation. Transcriptional profiling, along with validation experiments, subsequently revealed that an insufficient uptake of iron ions by bacteria upon binding to the TonB-dependent siderophore receptors is the antibacterial mechanism of Enoxolone. Finally, Enoxolone's acceptable toxicity was illustrated through immersion experiments. In summary, we have used virtual screening techniques for the first time in the development of antimicrobial agents in aquaculture. Through this process, we have identified Enoxolone as a promising compound targeting the TonB-dependent siderophore receptor of F. columnare. In addition, our findings will provide new ideas for the advancement of innovative antimicrobial medications in aquaculture.

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.

Herbal Products and Their Active Constituents Used Alone and in Combination with Antibiotics against Multidrug-Resistant Bacteria

The purpose of this review is to summarize the current knowledge acquired on herbal products and their active constituents with antimicrobial activity used alone and in combination with antibiotics against multidrug-resistant bacteria. The most promising herbal products and active constituents used alone against multidrug-resistant bacteria are Piper betle (methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, extended-spectrum beta-lactamase, Acinetobacter baumannii, Pseudomonas aeruginosa), Glycyrrhiza glabra (methicillin-resistant S. aureus, vancomycin-resistant Enterococcus, P. aeruginosa), and berberine (methicillin-resistant S. aureus, A. baumannii, P. aeruginosa), respectively. The synergistic effect of the combination of herbal products and their active constituents with antibiotics against multidrug-resistant bacteria are also described. These natural antibacterial agents can be promising sources of inhibitors, which can modulate antibiotic activity against multidrug-resistant bacteria, especially as efflux pump inhibitors. Other possible mechanisms of action of herbal therapy against multidrug-resistant bacteria including modification of the bacterial cell wall and/or membrane, inhibition of the cell division protein filamenting temperature sensitive Z-ring, and inhibition of protein synthesis and gene expression, all of which will also be discussed. Our review suggests that combination herbal therapy and antibiotics can be effectively used to expand the spectrum of their antimicrobial action. Therefore, combination therapy against multidrug-resistant bacteria may enable new choices for the treatment of infectious diseases and represents a potential area for future research.

Analysis of the network pharmacology and the structure-activity relationship of glycyrrhizic acid and glycyrrhetinic acid

Licorice, a herbal product derived from the root of Glycyrrhiza species, has been used as a sweetening agent and traditional herbal medicine for hundreds of years. Glycyrrhizic acid (GL) and glycyrrhetinic acid (GA) are the most important active ingredients in licorice. Both GL and GA have pharmacological effects against tumors, inflammation, viral infection, liver diseases, neurological diseases, and metabolic diseases. However, they also exhibit differences. KEGG analysis indicated that licorice is involved in neuroactive ligand‒receptor interactions, while 18β-GA is mostly involved in arrhythmogenic right ventricular cardiomyopathy. In this article, we comprehensively review the therapeutic potential of GL and GA by focusing on their pharmacological effects and working mechanisms. We systemically examine the structure-activity relationship of GL, GA and their isomers. Based on the various pharmacological activities of GL, GA and their isomers, we propose further development of structural derivatives of GA after chemical structure modification, with less cytotoxicity but higher targeting specificity. More research is needed on the clinical applications of licorice and its active ingredients.

Antimicrobial potentials of natural products against multidrug resistance pathogens: a comprehensive review

Antibiotic resistance is one of the critical issues, describing a significant social health complication globally. Hence, the discovery of novel antibiotics has acquired an increased attention particularly against drug-resistant pathogens. Natural products have served as potent therapeutics against pathogenic bacteria since the glorious age of antibiotics of the mid 20th century. This review outlines the various mechanistic candidates for dealing with multi-drug resistant pathogens and explores the terrestrial phytochemicals isolated from plants, lichens, insects, animals, fungi, bacteria, mushrooms, and minerals with reported antimicrobial activity, either alone or in combination with conventional antibiotics. Moreover, newly established tools are presented, including prebiotics, probiotics, synbiotics, bacteriophages, nanoparticles, and bacteriocins, supporting the progress of effective antibiotics to address the emergence of antibiotic-resistant infectious bacteria. Therefore, the current article may uncover promising drug candidates that can be used in drug discovery in the future.

Synthesis, Antiviral, and Antibacterial Activity of the Glycyrrhizic Acid and Glycyrrhetinic Acid Derivatives

Glycyrrhizic acid and its primary metabolite glycyrrhetinic acid, are the main active ingredients in the licorice roots (glycyrrhiza species), which are widely used in several countries of the world, especially in east asian countries (China, Japan). These ingredients and their derivatives play an important role in treating many diseases, especially infectious diseases such as COVID-19 and hepatic infections. This review aims to summarize the different ways of synthesising the amide derivatives of glycyrrhizic acid and the main ways to synthesize the glycyrrhitinic acid derivatives. Also, to determine the main biological and pharmacological activity for these compounds from the previous studies to provide essential data to researchers for future studies.

Supplementary Information

The online version contains supplementary material available at 10.1134/S1068162022050132.

18β-Glycyrrhetinic Acid Induces Metabolic Changes and Reduces Staphylococcus aureus Bacterial Cell-to-Cell Interactions

The rise in bacterial resistance to common antibiotics has raised an increased need for alternative treatment strategies. The natural antibacterial product, 18β-glycyrrhetinic acid (GRA) has shown efficacy against community-associated methicillin-resistant Staphylococcus aureus (MRSA), although its interactions against planktonic and biofilm modes of growth remain poorly understood. This investigation utilized biochemical and metabolic approaches to further elucidate the effects of GRA on MRSA. Prolonged exposure of planktonic MRSA cell cultures to GRA resulted in increased production of staphyloxanthin, a pigment known to exhibit antioxidant and membrane-stabilizing functions. Then, 1D ¹H NMR analyses of intracellular metabolite extracts from MRSA treated with GRA revealed significant changes in intracellular polar metabolite profiles, including increased levels of succinate and citrate, and significant reductions in several amino acids, including branch chain amino acids. These changes reflect the MRSA response to GRA exposure, including potentially altering its membrane composition, which consumes branched chain amino acids and leads to significant energy expenditure. Although GRA itself had no significant effect of biofilm viability, it seems to be an effective biofilm disruptor. This may be related to interference with cell–cell aggregation, as treatment of planktonic MRSA cultures with GRA leads to a significant reduction in micro-aggregation. The dispersive nature of GRA on MRSA biofilms may prove valuable for treatment of such infections and could be used to increase susceptibility to complementary antibiotic therapeutics.

The potential of glycyrrhizin and licorice extract in combating COVID-19 and associated conditions

BACKGROUND

Several recent studies have stated that glycyrrhizin and licorice extract are present in most traditional Chinese medicine formulas used against SARS-CoV-2 in China. Significant data are showing that glycyrrhizin and licorice extract have multiple beneficial activities in combating most features of SARS-CoV-2.

PURPOSE

The aim of current review was to highlight recent progresses in research that showed the evidence of the potential use of glycyrrhizin and licorice extract against COVID-19.

METHODOLOGY

We have reviewed the information published from 1979 to October 2020. These studies demonstrated the effects , use and safety of glycyrrhizin and icorice extract against viral infections,bacterial infections, inflammatory disorders of lung ( in vitro and in vivo).  These studies were collated through online electronic databases research (Academic libraries as PubMed, Scopus, Web of Science and Egyptian Knowledge Bank).

RESULTS

Pooled effect size of articles provides information about the rationale for using glycyrrhizin and licorice extract to treat COVID-19. Fifty studies demonstrate antiviral activity of glycyrrhizin and licorice extract. The most frequent mechanism of the antiviral activity is due to disrupting viral uptake into the host cells and disrupting the interaction between receptor- binding domain (RBD) of SARS-COV2 and ACE2 in recent articles. Fifty studies indicate that glycyrrhizin and licorice extract have significant antioxidant, anti-inflammatory and immunomodulatory effects. Twenty five studies provide evidence for the protective effect of glycyrrhizin and licorice extract against inflammation-induced acute lung injury and cardiovascular disorders.

CONCLUSION

The current study showed several evidence regarding the beneficial effects of glycyrrhizin and licorice extract in combating COVID-19. More randomized clinical trials are needed to obtain a precise conclusion.

Development of sodium carboxymethyl cellulose based polymeric microparticles for in situ hydrogel wound dressing formation

18β-glycyrrhetinic acid (Gly), a natural compound obtained from licorice, is known both for the anti-inflammatory and antioxidant activities and for this reason useful for wound treatment. Due to its poor solubility, Gly is not suitable for formulations used in conventional topical products such as gels, foams and creams. Polymeric bioadhesive microparticles (MP), loaded with Gly, were developed to be introduced in the wound bed and swell, once in contact with the exudate, to form a hydrogel in situ able to close the wound. The MP were prepared by spray drying method from the polymeric solution of polysaccharide sodium carboxymethyl cellulose (CMC) and copolymer Soluplus® (SL). Soluplus® introduction in MP composition, using a 3:1 ratio (CMC/SL wt./wt.), allowed to stabilize Gly in non-crystalline form, favoring the improvement of water solubility, and to obtain a spherical with rugged surface MP morphology. Ex vivo studies showed these MP maintain high swelling capability and are able to form in situ a hydrogel for wound repair. The controlled release of Gly from the hydrogel stimulates keratinocyte growth, potentially supporting the physiological healing processes.

Antibacterial and synergistic activity of 6β-hydroxy-3-oxolup-20(29)-en-28-oic acid (6β-hydroxy betunolic acid) isolated from Schumacheria castaneifolia vahl

Multi- drug resistant microbial pathogens are a serious global health problem and thus new antibacterial agents, which are effective both alone and in combination with traditional antibiotics, are urgently needed. Hence, the objective of the present study was to investigate the antibacterial activity of 6β-hydroxy-3-oxolup-20(29)-en-28-oic acid (6β-hydroxy betunolic acid) isolated from the bark of Schumacheria castaneifolia and its effect when combined with oxacillin. Antibacterial potential of 6β-hydroxy betunolic acid alone was performed using broth micro dilution assay against sixteen bacterial strains which included eight standard strains [Staphylococcus aureus (ATCC 29213 and ATCC 25923), Enterococcus faecalis (ATCC 29212), Escherichia coli (ATCC 35218 and ATCC 25922), carbapenemase producing Kebsiella pneumonia (ATCC BAA 1705), carbapenemase non-producing K. pneumonia (ATCC BAA 1706) and Pseudomonas aeruginosa (ATCC 27853)] and four strains each of clinically isolated meropenem resistant Acinetobactor sp. and methicillin resistant S. aureus (MRSA) which were included in the urgent threat list and serious threat list, respectively in 2019 by the Centers for Disease Control and Prevention in the United States. Its effect when combined with oxacillin was tested against S. aureus (ATCC 29213) and MRSAs using a checkerboard dilution method. The results indicated that 6β-hydroxy betunolic acid had antibacterial activity against the tested Gram positive organisms with MICs ranging from 16 to 32 mg L^-1 (MIC of oxacillin and meropenem ranged from 0.25-16 and 0.03-128 mg L^-1 respectively). The high MIC values (>1024 mg L^-1) of 6β-hydroxy betunolic acid against Gram negative strains indicated a likely lack of activity. Further, 6β-hydroxy betunolic acid exhibited synergistic effect with oxacillin against Staphylococcus aureus (0.49) and showed an additive effect against all the tested MRSAs. The present study suggested that the antibacterial activity of the 6β-hydroxy betunolic acid is restricted to Staphylococcus isolates and possibly Enterococcus faecalis. Further testing on different types of Gram positives and identification of the exact mechanism of action would be of importance.

Identifying the Chinese Herbal Medicine Network and Core Formula for Allergic Rhinitis on a Real-World Database

MATERIALS AND METHODS

Patients with a primary diagnosis of AR (ICD-9-CM code: 477.9) in 2010 were included, and the National Health Insurance Research Database in Taiwan was used as the data source. Association rule mining and social network analysis were used to establish and explore the CHM network. Possible molecular pathways of the CHM network were summarized and compared with commonly used western medicine (WM) by conducting overrepresentation analysis in the Reactome pathway database. The potential proteins acted by CHMs were obtained from the CHM ingredient-protein databases, including STITCH, TCMSP, TCMID, and TCM@Taiwan.

RESULTS

There were 89,148 AR subjects found in 2010, and a total of 33,507 patients ever used CHM. On an average, 5.6 types of CHMs were utilized per prescription. Xin-Yi-Qing-Fei-Tang was used most frequently (25.5% of 222,279 prescriptions), while Xiao-Qing-Long-Tang with Xin-Yi-San was the most commonly prescribed CHM-CHM combination. Up to six distinctive clusters could be found among the CHM network, and core CHMs could be found for AR, such as Xiao-Qing-Long-Tang and Xin-Yi-Qing-Fei-Tang. A total of 140 molecular pathways were covered by the CHM network (2,432 ingredients from 31 kinds of CHMs), while 39 WMs covered 55 pathways. Among pathways responding to the immune system, WM mainly acted on cytokine signaling-related pathways, while CHM mostly acted on neutrophil/macrophage-related innate pathways and dendritic cell-related adaptive immunity pathways.

CONCLUSION

Our study demonstrated and analyzed the CHM network for AR. Core CHM for AR and possible molecular pathways were presented as well, and this information is crucial for researchers to select candidates for CHM-related studies.

The Revaluation of Plant-Derived Terpenes to Fight Antibiotic-Resistant Infections

The discovery of antibiotics has revolutionized the medicine and treatment of microbial infections. However, the current scenario has highlighted the difficulties in marketing new antibiotics and an exponential increase in the appearance of resistant strains. On the other hand, research in the field of drug-discovery has revaluated the potential of natural products as a unique source for new biologically active molecules and scaffolds for the medicinal chemistry. In this review, we first contextualized the worldwide problem of antibiotic resistance and the importance that natural products of plant origin acquire as a source of new lead compounds. We then focused on terpenes and their potential development as antimicrobials, highlighting those studies that showed an activity against conventional antibiotic-resistant strains.

The Revaluation of Plant-Derived Terpenes to Fight Antibiotic-Resistant Infections

The discovery of antibiotics has revolutionized the medicine and treatment of microbial infections. However, the current scenario has highlighted the difficulties in marketing new antibiotics and an exponential increase in the appearance of resistant strains. On the other hand, research in the field of drug-discovery has revaluated the potential of natural products as a unique source for new biologically active molecules and scaffolds for the medicinal chemistry. In this review, we first contextualized the worldwide problem of antibiotic resistance and the importance that natural products of plant origin acquire as a source of new lead compounds. We then focused on terpenes and their potential development as antimicrobials, highlighting those studies that showed an activity against conventional antibiotic-resistant strains.

The Revaluation of Plant-Derived Terpenes to Fight Antibiotic-Resistant Infections

The discovery of antibiotics has revolutionized the medicine and treatment of microbial infections. However, the current scenario has highlighted the difficulties in marketing new antibiotics and an exponential increase in the appearance of resistant strains. On the other hand, research in the field of drug-discovery has revaluated the potential of natural products as a unique source for new biologically active molecules and scaffolds for the medicinal chemistry. In this review, we first contextualized the worldwide problem of antibiotic resistance and the importance that natural products of plant origin acquire as a source of new lead compounds. We then focused on terpenes and their potential development as antimicrobials, highlighting those studies that showed an activity against conventional antibiotic-resistant strains.

New Technological Approach for Glycyrrethic Acid Oral and Topical Administration

Background:

18β- glycyrrhetinic acid (Gly) is the major bioactive component of licorice roots and rhizomes of the Glycyrrhiza glabra species. It shows many activities such as antiviral, anti-inflammatory, antioxidant, antimicrobial, and antifungal, however, its use in the health field is very limited due to the low water solubility.

Methods:

This paper deals with the development of a new technological approach for Gly dissolution rate enhancement. It consists of Gly intercalation (guest) in the interlamellar spaces between the inorganic spaces (host) of the anionic clays “hydrotalcites” (HTlc) to obtain hybrids MgAl-HTlc-Gly and ZnAl-HTlc-Gly. Gly can find applications in both systemic and local therapies, thus advantages of the use of the hybrids in these two fields were investigated.

Results:

Gly dissolution rate from hybrids in the intestinal environment, site in which it is preferentially absorbed, resulted enhanced (ZnAl-HTlc-Gly > MgAl-HTlc-Gly) compared to the crystalline form, thereby, making them suitable for oral administration as dry powder in hard capsules.

:

For a local therapy, bioadhesive, vaginal emulgels loaded with the hybrids were developed. These showed suitable mucoadhesive property to the vaginal mucosa, necessary to prolong the residence time in the application site. The emulgel containing ZnAl-HTlc-Gly showed a faster and higher release profile than that containing MgAl- HTlc-Gly.

Conclusions:

The obtained results suggest that Gly intercalation into HTlc, especially in ZnAl-HTlc, allows to enhance Gly dissolution when the hybrids are formulated both as oral or topical products.

The Effect of SBA-15 Surface Modification on the Process of 18β-Glycyrrhetinic Acid Adsorption: Modeling of Experimental Adsorption Isotherm Data

This study aimed at the adsorption of 18β-glycyrrhetinic acid (18β-GA), a pentacyclic triterpenoid derivative of oleanane type, onto functionalized mesoporous SBA-15 silica and non-porous silica (Aerosil^®) as the reference adsorbent. Although 18β-GA possesses various beneficial pharmacological properties including antitumor, anti-inflammatory, and antioxidant activity, it occurs is small amounts in plant materials. Thus, the efficient methods of this bioactive compound enrichment from vegetable raw materials are currently studied. Siliceous adsorbents were functionalized while using various alkoxysilane derivatives, such as (3-aminopropyl)trimethoxysilane (APTMS), [3-(methylamino)propyl]trimethoxysilane (MAPTMS), (N,N-dimethylaminopropyl)trimethoxysilane (DMAPTMS), and [3-(2-aminothylamino)propyl] trimethoxysilane (AEAPTMS). The effect of silica surface modification with agents differing in the structure and the order of amine groups on the adsorption capacity of the adsorbent and adsorption efficiency were thoroughly examined. The equilibrium adsorption data were analyzed while using the Langmuir, Freundlich, Redlich-Peterson, Temkin, Dubinin-Radushkevich, and Dubinin-Astakhov isotherms. Both linear regression and nonlinear fitting analysis were employed in order to find the best-fitted model. The adsorption isotherms of 18β-GA onto silicas functionalized with APTMS, MAPTMS, and AEAPTMS indicate the Langmuir-type adsorption, whereas sorbents modified with DMAPTMS show the constant distribution of the adsorbate between the adsorbent and the solution regardless of silica type. The Dubinin-Astakhov, Dubinin-Radushkevich, and Redlich-Peterson equations described the best the process of 18β-GA adsorption onto SBA-15 and Aerosil^® silicas that were functionalized with APTMS, MAPTMS, and AEAPTMS, regardless of the method that was used for the estimation of isotherm parameters. Based on nonlinear fitting analysis (Dubinin-Astakhov model), it can be concluded that SBA-15 sorbent that was modified with APTMS, MAPTMS, and AEAPTMS is characterized by twice the adsorption capacity (202.8–237.3 mg/g) as compared to functionalized non-porous silica (118.2–144.2 mg/g).