A polyphenolic flavonoid glabridin: Oxidative stress response in multidrug-resistant Staphylococcus aureus

Bioactive substance contents and therapeutic potential for skin inflammation of an herbal gel containing Derris reticulata and Glycyrrhiza glabra

CONTEXT

Derris reticulata Craib. and Glycyrrhiza glabra L., of the Fabaceae, have been used as active components in Thai herbal formulas for the treatment of fever and skin diseases.

OBJECTIVE

To evaluate the physicochemical and pharmacological properties of the developed herbal gel formulation containing the combined extract from D. reticulata stem wood and G. glabra root (RGF).

MATERIALS AND METHODS

The potential of the herbal gel formulation containing RGF (8% w/w) as the active ingredient was studied by evaluating the anti-inflammatory, antioxidant, and anti-Staphylococcus aureus activities using quantitative reverse transcription-polymerase chain reaction assay, spectrophotometric method, and broth microdilution technique, respectively. The reference standards for the biological testing included Nω-nitro-L-arginine (L-NA), ascorbic acid, catechin, and penicillin G. The stability study of the RGF herbal gel was performed by a heating-cooling test (at 45 °C for 24 h and at 4 °C for 24 h/1 cycle; for 6 cycles), and the bioactive marker compounds in the herbal gel were investigated by the HPLC technique.

RESULTS

RGF showed promising pharmacological effects, particularly on its anti-inflammatory property (IC50 73.86 µg/mL), compared to L-NA (IC50 47.10 µg/mL). The RGF-containing gel demonstrated anti-inflammatory (IC50 3.59 mg/mL) and free radical scavenging effects (IC50 0.05-4.39 mg/mL), whereas it had no anti-S. aureus activity (MIC > 10 mg/mL). The active ingredient in the developed herbal gel significantly inhibited lipopolysaccharide-induced nitric oxide production by downregulating iNOS mRNA levels. The contents of the bioactive markers in the RGF gel (lupinifolin and glabridin) did not change significantly after stability testing.

DISCUSSION AND CONCLUSIONS

The RGF-containing gel has potential to be further developed as an herbal product for the treatment of skin inflammation.

Disinfectant efficacy of glabridin against dried and biofilm cells of Listeria monocytogenes and the impact of residual organic matter

Glabridin is an antimicrobial compound which can be extracted from plants, such as liquorice (Glycyrrhiza glabra) roots. Although its activity against foodborne pathogens and spoilage microorganisms has already been reported, the investigation of potential applications as a surface disinfectant is still largely unexplored. Hence, this study evaluated the disinfectant efficacy of glabridin against Listeria monocytogenes. The activity of glabridin was first tested in vitro in a nutrient-rich medium against eight strains of L. monocytogenes, including food isolates and the model strain EGDe. The tested strains showed similar susceptibility with minimal inhibitory and bactericidal concentrations of 12.5 µg/mL and 25 µg/mL, respectively. Subsequently, L. monocytogenes L6, FBR17 and EGDe were selected to assess the efficacy of glabridin against dried cells (according to the European standard EN 13697:2015 + A1:2019) and biofilm cells on stainless steel surfaces. Moreover, the impact of food residual organic matter was investigated using skim milk, cantaloupe and smoked salmon solution as soiling components. Our results showed that applying 200 µg/mL of glabridin resulted in a substantial reduction (>3 log10) of dried and biofilm cells of L. monocytogenes in standard conditions (i.e. low level of residual organic matter). Cantaloupe soiling components slightly reduced the activity of glabridin, while the efficacy of glabridin when tested with salmon and skim milk residuals was substantially affected. Comparative analysis using standardized protein contents provided evidence that the type of food matrices and type of proteins may impact the activity of glabridin as a disinfectant. Overall, this study showed low strain variability for the activity of glabridin against L. monocytogenes and shed light on the possible application of this natural antimicrobial compound as a surface disinfectant.

In vitro and in vivo enhancement effect of glabridin on the antibacterial activity of colistin, against multidrug resistant Escherichia coli strains

BACKGROUND

The increase in antimicrobial resistance leads to complications in treatments, prolonged hospitalization, and increased mortality. Glabridin (GLA) is a hydroxyisoflavan from Glycyrrhiza glabra L. that exhibits multiple pharmacological activities. Colistin (COL), a last-resort antibiotic, is increasingly being used in clinic against Gram-negative bacteria. Previous reports have shown that GLA is able to sensitize first line antibiotics such as norfloxacin and vancomycin on Staphylococcus aureus, implying that the use of GLA as an antibiotic adjuvant is a promising strategy for addressing the issue of drug resistance. However, the adjuvant effect on other antibiotics, especially COL, on Gram-negative bacteria such as Escherichia coli has not been studied.

PURPOSE

The objective of our study was to investigate the targets of GLA and the synergistic effect of GLA and COL in E. coli, and to provide further evidence for the use of GLA as an antibiotic adjuvant to alleviate the problem of drug resistance.

METHODS

We first investigated the interaction between GLA and enoyl-acyl carrier protein reductase, also called "FabI", through enzyme inhibition assay, differential scanning fluorimetry, isothermal titration calorimetry and molecular docking assay. We tested the transmembrane capacity of GLA on its own and combined it with several antibiotics. The antimicrobial activities of GLA and COL were evaluated against six different susceptible and resistant E. coli in vitro. Their interactions were analyzed using checkerboard assay, time-kill curve and CompuSyn software. A series of sensitivity tests was conducted in E. coli overexpressing the fabI gene. The development of COL resistance in the presence of GLA was tested. The antimicrobial efficacy of GLA and COL in a mouse model of urinary tract infection was assessed. The anti-biofilm effects of GLA and COL were investigated.

RESULTS

In this study, enzyme kinetic analysis and thermal analysis provided evidence for the interaction between GLA and FabI in E. coli. GLA enhanced the antimicrobial effect of COL and synergistically suppressed six different susceptible and resistant E. coli with COL. Overexpression experiments showed that targeted inhibition of FabI was a key mechanism by which GLA synergistically enhanced COL activity. The combination of GLA and COL slowed the development of COL resistance in E. coli. Combined GLA and COL treatment significantly reduced bacterial load and mitigated urinary tract injury in a mouse model of E. coli urinary tract infection. Additionally, GLA + COL inhibited the formation and eradication of biofilms and the synthesis of curli.

CONCLUSION

Our findings indicate that GLA synergistically enhances antimicrobial activities of COL by targeting inhibition of FabI in E. coli. GLA is expected to continue to be developed as an antibiotic adjuvant to address drug resistance issues.

Quantitative determination of the antibacterial activity of licorice (Glycyrrhiza glabra) and tetracycline gel against Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg) and Prevotella intermedia (Pi) - a microbiological in vitro study

OBJECTIVES

The aim of this study was to evaluate and compare the antibacterial efficacy of licorice gel and tetracycline gel against Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia.

METHODS

An indigenously prepared 50 μL licorice and tetracycline gel was subjected to antibacterial sensitivity test (thrice) against Aa, Pg, Pi by agar well diffusion method using Brain Heart Infusion media. Colonies of Aa, Pg, Pi was transferred into broth and incubated at 37 °C for 24 h and diameter of inhibition zone was measured.

RESULTS

The drug release profile of licorice gel at six regular intervals was higher when compared to tetracycline. MIC of licorice gel (50 μg/mL) against Aa (14 mg), Pg (7 mg), Pi (7 mg) respectively. The diameter of inhibition zone of licorice gel was significant against Aa when compared to tetracycline gel. However, tetracycline gel exhibited significant diameter of inhibition zone against Pg and Pi when compared to licorice gel. There was a statistical significance difference between licorice and tetracycline gel against Aa (p=0.043*), Pg (p=0.037*), Pi (p=0.046*) while assessing antibacterial sensitivity test.

CONCLUSIONS

Licorice gel has anti-inflammatory and anti-microbial properties which can act against periodontal pathogens and can be considered in treating periodontal disease at low concentrations. Therefore, it can be used as an adjunctive local drug delivery agent to non-surgical periodontal therapy (NSPT) in treating periodontal disease.

Unveiling the mechanism of essential oil action against skin pathogens: from ancient wisdom to modern science

Essential oils are among the most well-known phyto-compounds, and since ancient times, they have been utilized in medicine. Over 100 essential oils have been identified and utilized as therapies for various skin infections and related ailments. While numerous commercial medicines are available in different dosage forms to treat skin diseases, the persisting issues include their side effects, toxicity, and low efficacy. As a result, researchers are seeking novel classes of compounds as substitutes for synthetic drugs, aiming for minimal side effects, no toxicity, and high efficacy. Essential oils have shown promising antimicrobial activity against skin-associated pathogens. This review presents essential knowledge and scientific information regarding essential oil's antimicrobial capabilities against microorganisms that cause skin infections. Essential oils mechanisms against different pathogens have also been explored. Many essential oils exhibit promising activity against various microbes, which has been qualitatively assessed using the agar disc diffusion experiment, followed by determining the minimum inhibitory concentration for quantitative evaluation. It has been observed that Staphylococcus aureus and Candida albicans have been extensively researched in the context of skin-related infections and their antimicrobial activity, including established modes of action. In contrast, other skin pathogens such as Staphylococcus epidermidis, Streptococcus pyogens, Propionibacterium acnes, and Malassezia furfur have received less attention or neglected. This review report provides an updated understanding of the mechanisms of action of various essential oils with antimicrobial properties. This review explores the anti-infectious activity and mode of action of essential against distinct skin pathogens. Such knowledge can be valuable in treating skin infections and related ailments.

Highly swellable, cytocompatible and biodegradeable guar gum-based hydrogel system for controlled release of bioactive components of liquorice (Glycyrrhiza glabra L.): Synthesis and evaluation

Glycyrrhiza glabra Linn (liquorice) has been widely used for therapeutic purposes to treat digestive disorders, immunomodulatory disorders, inflammatory disorders, diabetes, viral infections, and cancer. Liquorice contains a wide variety of bioactive compounds, including glycyrrhizin, flavonoids, and terpenoids. Several factors compromise their therapeutic efficacy, such as poor pharmacokinetic profiles and physicochemical properties. Therefore, to improve its overall effectiveness, liquorice solid dispersion (LSD) was incorporated into biopolymer-based guar gum-grafted-2-acrylamido-2-methylpropane sulfonic acid (Guar gum-g-AMPS) hydrogels designed for controlled delivery via the oral route and characterized. The qualitative analysis of LSD revealed 51 compounds. Hydrogel structural properties were assessed for their effect on swelling and release. The highest swelling ratio (6413 %) and drug release (84.12 %) occurred at pH 1.2 compared to pH 7.4 (swelling ratio of 2721 % and drug release of 79.36 %) in 48 h. The hydrogels exhibited high porosity (84.23 %) and biodegradation (9.30 % in 7 days). In vitro hemolysis tests have demonstrated the compatibility of the hydrogel with blood. CCK-8 assay confirmed the biocompatibility of the synthesized hydrogel using osteoblasts and RIN-m5f cells. LSD exhibited good anti-inflammatory activity when loaded into hydrogels after being subjected to protein denaturation experiments. Moreover, LSD-loaded hydrogels have good antioxidant and antibacterial properties.

Introducing the glycyrrhizic acid and glabridin rich genotypes from the cultivated Iranian licorice (Glycyrrhiza glabra L.) populations to exploit in production systems

Currently, the stable, uniform, and highly efficient production of raw materials for pharmaceutical companies has received special attention. To meet these criteria and reduce harvesting pressure on the natural habitats of licorice (Glycyrrhiza glabra L.), cultivation of this valuable plant is inevitable. In the present study, to introduce the glycyrrhizic acid (GA)- and glabridin-rich genotypes from cultivated Iranian licorice, forty genotypes from eight high-potential wild populations were cultivated and evaluated under the same environmental conditions. The GA content varied from 5.00 ± 0.04 mg/g DW (TF2 genotype) to 23.13 ± 0.02 mg/g DW (I5 genotype). The highest and lowest glabridin content were found in the K2 (0.72 ± 0.021 mg/g DW) and M5 (0.02 ± 0.002 mg/g DW) genotypes, respectively. The rutin content in the leaves of the studied genotypes varied from 1.27 ± 0.02 mg/g DW in E4 to 3.24 ± 0.02 mg/g DW in BO5 genotypes. The genotypes from the Ilam population were characterized by higher vegetative growth and yield traits in the aerial parts and roots. The average root dry yield was 2.44 tons per hectare (t/ha) among the studied genotypes and a genotype from Ilam (I5) yielded the maximum value (3.08 ± 0.034 t/ha). The highest coefficient of variation among the genotypes was observed for leaf width (CV = 34.9%). The GA and glabridin-rich genotypes introduced in this study can be used in the future breeding programs to release new bred licorice cultivars.

Discovery of indolylacryloyl-derived oxacins as novel potential broad-spectrum antibacterial candidates

The emergence of serious bacterial resistance towards clinical oxacins poses a considerable threat to global public health, necessitating the development of novel structural antibacterial agents. Seven types of novel indolylacryloyl-derived oxacins (IDOs) were designed and synthesized for the first time from commercial 3,4-difluoroaniline via an eight-step procedure. The synthesized compounds were characterized by modern spectroscopic techniques. All target molecules were evaluated for antimicrobial activities. Most of the prepared IDOs showed a broad antibacterial spectrum and strong activities against the tested strains, especially ethoxycarbonyl IDO 10d (0.25-0.5 μg/mL) and hydroxyethyl IDO 10e (0.25-1 μg/mL) exhibited much superior antibacterial efficacies to reference drug norfloxacin. These highly active IDOs also displayed low hemolysis, cytotoxicity and resistance, as well as rapid bactericidal capacity. Further investigations indicated that ethoxycarbonyl IDO 10d and hydroxyethyl IDO 10e could effectively reduce the exopolysaccharide content and eradicate the formed biofilm, which might delay the development of drug resistance. Preliminary exploration of the antibacterial mechanism revealed that active IDOs could not only destroy membrane integrity, resulting in changes in membrane permeability, but also promote the accumulation of reactive oxygen species, leading to the production of malondialdehyde and decreased bacterial metabolism. Moreover, they exhibited the capability to bind with DNA and DNA gyrase, forming supramolecular complexes through various noncovalent interactions, thereby inhibiting DNA replication and causing bacterial death. All the above results suggested that the newly developed indolylacryloyl-derived oxacins should hold great promise as potential multitargeting broad-spectrum antibacterial candidates to overcome drug resistance.

Phytochemical Profiles and Antimicrobial Activity of Selected Populus spp. Bud Extracts

Buds of poplar trees (Populus species) are often covered with sticky, usually polyphenol-rich, exudates. Moreover, accessible data showed that some Populus bud extracts may be excellent antibacterial agents, especially against Gram-positive bacteria. Due to the fragmentary nature of the data found, we conducted a systematic screening study. The antimicrobial activity of two extract types (semi-polar-ethanolic and polar-ethanolic-water (50/50; V/V)) from 27 bud samples of different poplar taxons were compared. Antimicrobial assays were performed against Gram-positive (five strains) and Gram-negative (six strains) bacteria as well as fungi (three strains) and covered the determination of minimal inhibitory, bactericidal, and fungicidal concentrations. The composition of extracts was later investigated by ultra-high-performance liquid chromatography coupled with ultraviolet detection (UHPLC-DAD) and with electrospray-quadrupole-time-of-flight tandem mass spectrometry (UHPLC-ESI-qTOF-MS). As a result, most of the extracts exhibited good (MIC ≤ 62.5 µg/mL) or moderate (62.5 < MIC ≤ 500 µg/mL) activity against Gram-positives and Helicobacter pylori, as well as fungi. The most active were ethanolic extracts from P. trichocarpa, P. trichocarpa clone 'Robusta', and P. tacamahaca × P. trichocarpa. The strongest activity was observed for P. tacamahaca × P. trichocarpa. Antibacterial activity was supposedly connected with the abundant presence of flavonoids (pinobanksin, pinobanksin 3-acetate, chrysin, pinocembrin, galangin, isosakuranetin dihydrochalcone, pinocembrin dihydrochalcone, and 2',6'-dihydroxy-4'-methoxydihydrochalcone), hydroxycinnamic acids monoesters (p-methoxycinnamic acid cinnamyl ester, caffeic acid phenethylate and different isomers of prenyl esters), and some minor components (balsacones).

Three Licorice Extracts' Impact on the Quality of Fresh-Cut Sweet Potato (Ipomoea batatas (L.) Lam) Slices

The quality of fresh-cut produce, particularly sweet potatoes, is crucial for their value. Licorice extract is an optional additive in fresh-cut sweet potatoes. This study examined the impact of three licorice extracts (licorice acid, LA; licorice flavonoids, LF; and licorice polysaccharides, LP) on the quality of fresh-cut sweet potato slices (FCSPSs) for one week of storage. After one week of storage, the extracts showed varying effects on FCSPSs. LA and LF treatments reduced the area proportion of browning (APB), while LP treatments increased APB and decreased L* values. Antioxidant experiments revealed that LP treatments increased PPO and POD activity while reducing SOD activity. The concentrations of the three licorice extracts showed a strong negative correlation with SOD activity. In conclusion, LP harmed the appearance and antioxidant qualities of FCSPSs. LA and LF may be suitable additive components for FCSPSs, and 30 mg/mL LA and LF treatments were found to maintain the appearance and texture quality of FCSPSs during storage. Therefore, careful consideration should be given when using LP as a food additive for FCSPSs.

Effects of the antimicrobial glabridin on membrane integrity and stress response activation in Listeria monocytogenes

Glabridin is a prenylated isoflavan which can be extracted from liquorice roots and has shown antimicrobial activity against foodborne pathogens and spoilage microorganisms. However, its application may be hindered due to limited information about its mode of action. In this study, we aimed to investigate the mode of action of glabridin using a combined phenotypic and proteomic approach on Listeria monocytogenes. Fluorescence and transmission electron microscopy of cells exposed to glabridin showed membrane permeabilization upon treatment with lethal concentrations of glabridin. Comparative proteomics analysis of control cells and cells exposed to sub-lethal concentrations of glabridin showed upregulation of proteins related to the two-component systems LiaSR and VirRS, confirming cell envelope damage during glabridin treatment. Additional upregulation of SigmaB regulon members signified activation of the general stress response in L. monocytogenes during this treatment. In line with the observed upregulation of cell envelope and general stress response proteins, sub-lethal treatment of glabridin induced (cross)protection against lethal heat and low pH stress and against antimicrobials such as nisin and glabridin itself. Overall, this study sheds light on the mode of action of glabridin and activation of the main stress responses to this antimicrobial isoflavan and highlights possible implications of its use as a naturally derived antimicrobial compound.

Chinese herbal compound for multidrug-resistant or extensively drug-resistant bacterial pneumonia: a meta-analysis and trial sequential analysis with association rule mining to identify core herb combinations

Purpose: Antibiotic-resistant bacterial pneumonia poses a significant therapeutic challenge. In China, Chinese herbal compound (CHC) is commonly used to treat bacterial pneumonia. We aimed to evaluate the efficacy and safety of CHC and identify core herb combinations for the treatment of multidrug-resistant or extensively drug-resistant bacterial pneumonia. Methods: Stata 16 and TSA 0.9.5.10 beta software were used for meta-analysis and trial sequential analysis (TSA), respectively. Exploring the sources of heterogeneity through meta-regression and subgroup analysis. Results: Thirty-eight studies involving 2890 patients were included in the analyses. Meta-analysis indicated that CHC combined with antibiotics improved the response rate (RR = 1.24; 95% CI: 1.19-1.28; p < 0.0001) and microbiological eradication (RR = 1.41; 95% CI: 1.27-1.57; p < 0.0001), lowered the white blood cell count (MD = -2.09; 95% CI: -2.65 to -1.53; p < 0.0001), procalcitonin levels (MD = -0.49; 95% CI: -0.59 to -0.40; p < 0.0001), C-reactive protein levels (MD = -11.80; 95% CI: -15.22 to -8.39; p < 0.0001), Clinical Pulmonary Infection Scores (CPIS) (MD = -1.97; 95% CI: -2.68 to -1.26; p < 0.0001), and Acute Physiology and Chronic Health Evaluation (APACHE)-II score (MD = -4.08; 95% CI: -5.16 to -3.00; p < 0.0001), shortened the length of hospitalization (MD = -4.79; 95% CI: -6.18 to -3.40; p < 0.0001), and reduced the number of adverse events. TSA indicated that the response rate and microbiological eradication results were robust. Moreover, Scutellaria baicalensis Georgi, Fritillaria thunbergii Miq, Lonicera japonica Thunb, and Glycyrrhiza uralensis Fisch were identified as core CHC prescription herbs. Conclusion: Compared with antibiotic treatment, CHC + antibiotic treatment was superior in improving response rate, microbiological eradication, inflammatory response, CPIS, and APACHE-II score and shortening the length of hospitalization. Association rule analysis identified four core herbs as promising candidates for treating antibiotic-resistant bacterial pneumonia. However, large-scale clinical studies are still required. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42023410587.

Proposed mechanisms of action of herbal drugs and their biologically active constituents in the treatment of coughs: an overview

Various medicinal plants find their use in cough treatment, based on traditions and long-term experience. Pharmacological principles of their action, however, are much less known. Herbal drugs usually contain a mixture of potentially active compounds, which can manifest diverse effects. Expectorant or antitussive effects, which can be accompanied by others, such as anti-inflammatory or antibacterial, are probably the most important in the treatment of coughs. The aim of this review is to summarize the current state of knowledge of the effects of medicinal plants or their constituents on cough, based on reliable pharmacological studies. First, a comprehensive description of each effect is provided in order to explain the possible mechanism of action in detail. Next, the results related to individual plants and substances are summarized and critically discussed based on pharmacological in vivo and in vitro investigation.

A review of the bioactive properties of Mongolian plants, with a focus on their potential as natural food preservatives

Consumers have recently preferred food that is easy to make and of excellent quality, as well as food that is safe, natural, and minimally processed, but has a longer shelf life. Food deteriorates over time as a result of microbiological, chemical, or physical changes. Phytochemicals derived from medicinal and food plants have long been recognized for their biological activity to protect plants. These bioactivities are designed to increase the shelf life of food while inhibiting the growth of microorganisms. The use of natural plant food preservatives containing bioactive compounds as health-promoting agents is particularly intriguing. Furthermore, due to their effectiveness against food spoilage and foodborne pathogens, natural plant-origin antimicrobial compounds have been investigated as alternatives to synthetic antimicrobial compounds for preserving food quality. This review focused on the plant composition and properties that can be utilized as a natural food preservative, as well as the possibilities of using Mongolian medicinal plants.

Evolving biofilm inhibition and eradication in clinical settings through plant-based antibiofilm agents

BACKGROUND

After almost 100 years since evidence of biofilm mode of growth and decades of intensive investigation about their formation, regulatory pathways and mechanisms of antimicrobial tolerance, nowadays there are still no therapeutic solutions to eradicate bacterial biofilms and their biomedical related issues.

PURPOSE

This review intends to provide a comprehensive summary of the recent and most relevant published studies on plant-based products, or their isolated compounds with antibiofilm activity mechanisms of action or identified molecular targets against bacterial biofilms. The objective is to offer a new perspective of most recent data for clinical researchers aiming to prevent or eliminate biofilm-associated infections caused by bacterial pathogens.

METHODS

The search was performed considering original research articles published on PubMed, Web of Science and Scopus from 2015 to April 2023, using keywords such as "antibiofilm", "antivirulence", "phytochemicals" and "plant extracts".

RESULTS

Over 180 articles were considered for this review with a focus on the priority human pathogens listed by World Health Organization, including Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae and Escherichia coli. Inhibition and detachment or dismantling of biofilms formed by these pathogens were found using plant-based extract/products or derivative compounds. Although combination of plant-based products and antibiotics were recorded and discussed, this topic is currently poorly explored and only for a reduced number of bacterial species.

CONCLUSIONS

This review clearly demonstrates that plant-based products or derivative compounds may be a promising therapeutic strategy to eliminate bacterial biofilms and their associated infections. After thoroughly reviewing the vast amount of research carried out over years, it was concluded that plant-based products are mostly able to prevent biofilm formation through inhibition of quorum sensing signals, but also to disrupt mature biofilms developed by multidrug resistant bacteria targeting the biofilm extracellular polymeric substance. Flavonoids and phenolic compounds seemed the most effective against bacterial biofilms.

Antibacterial Effect of Combinations of Salvia officinalis and Glycyrrhiza glabra Hydroalcoholic Extracts against Enterococcus spp

Enterococcus spp. are a common culprit behind the failure of endodontic treatments, primarily due to their notorious resistance to antimicrobial agents. Considering this challenge, this study was conducted to assess the antimicrobial efficacy of a unique blend of hydroalcoholic extracts sourced from Salvia officinalis and Glycyrrhiza glabra against biofilms formed by Enterococcus faecalis and Enterococcus faecium. The chemical composition of these plant extracts was rigorously characterized, with primary compound quantification achieved through high-performance liquid chromatography (HPLC-DAD) analysis. Additionally, this study determined the minimal bactericidal concentrations of these extracts and evaluated their potential to combat biofilms by quantifying colony-forming units per milliliter (CFU/mL). The findings reveal that the simultaneous application of both extracts yielded additive and synergistic effects against E. faecalis and E. faecium, including both ATCC and clinical strains. Impressively, after a 24 h exposure, these extract combinations demonstrated efficacy comparable to that of a 0.12% chlorhexidine solution, establishing a statistically significant difference from the negative control group. Consequently, the concurrent use of these extracts emerges as a promising alternative antimicrobial strategy for addressing Enterococcus spp. in endodontic treatments, holding substantial potential for clinical applications in this context.

Synergistic Effect of Sophora japonica and Glycyrrhiza glabra Flavonoid-Rich Fractions on Wound Healing: In Vivo and Molecular Docking Studies

Glycyrrhiza glabra and Sophora japonica (Fabaceae) are well-known medicinal plants with valuable secondary metabolites and pharmacological properties. The flavonoid-rich fractions of G. glabra roots and S. japonica leaves were prepared using Diaion column chromatography, and the confirmation of flavonoid richness was confirmed using UPLC-ESI-MS profiling and total phenolics and flavonoids assays. UPLC-ESI-MS profiling of the flavonoid-rich fraction of G. glabra roots and S. japonica leaves resulted in the tentative identification of 32 and 23 compounds, respectively. Additionally, the wound healing potential of topical preparations of each fraction, individually and in combination (1:1) ointment and gel preparations, were investigated in vivo, supported by histopathological examinations and biomarker evaluations, as well as molecular docking studies for the major constituents. The topical application of G. glabra ointment and gel, S. japonica ointment and gel and combination preparations significantly increase the wound healing rate and the reduction of oxidative stress in the wound area via MDA reduction and the elevation of reduced GSH and SOD levels as compared to the wound and Nolaver®-treated groups. The molecular docking study revealed that that major compounds in G. glabra and S. japonica can efficiently bind to the active sites of three proteins related to wound healing: glycogen synthase kinase 3-β (GSK3-β), matrix metalloproteinases-8 (MMP-8) and nitric oxide synthase (iNOS). Consequently, G. glabra roots and S. japonica leaves may be a rich source of bioactive metabolites with antioxidant, anti-inflammatory and wound healing properties.

Honokiol reduces fungal burden and ameliorate inflammation lesions of Aspergillus fumigatus keratitis via Dectin-2 down-regulation

PURPOSE

To screen and identify the mechanism of honokiol on anti-fungi and anti-inflammation in fungal keratitis (FK) through bioinformatic analysis and biological experiments.

METHODS

Transcriptome profile demonstrated differential expression genes (DEGs) of Aspergillus fumigatus keratitis between PBS-treated and honokiol-treated groups via bioinformatics analyses. Inflammatory substances were quantified by qRT-PCR, Western blot and ELISA, and macrophage polarization was examined by flow cytometry. Periodic acid Schiff staining and morphological interference assay were used to detect hyphal distribution in vivo and fungal germination in vitro, respectively. Electron microscopy was to illustrate hyphal microstructure.

RESULTS

Illumina sequencing demonstrated that compared with the honokiol group, 1175 up-regulated and 383 down-regulated genes were induced in C57BL/6 mice Aspergillus fumigatus keratitis with PBS treatment. Through GO analysis, some differential expression proteins (DEPs) played major roles in biological processes, especially fungal defense and immune activation. KEGG analysis provided fungus-related signaling pathways. PPI analysis demonstrated that DEPs from multiple pathways form a close-knit network, providing a broader context for FK treatment. In biological experiments, Dectin-2, NLRP3 and IL-1β were upregulated by Aspergillus fumigatus to evaluate immune response. Honokiol could reverse the trend, comparable to Dectin-2 siRNA interference. Meanwhile, honokiol could also play an anti-inflammatory role via promoting M2 phenotype polarization. Moreover, honokiol reduced hyphal distribution in the stroma, delayed germination, and destroyed the hyphal cell membrane in-vitro.

CONCLUSIONS

Honokiol possesses anti-fungal and anti-inflammatory effects in Aspergillus fumigatus keratitis and may develop a potential and safe therapeutic modality for FK.

Synthesis and Biological Evaluation of Piperazine Hybridized Coumarin Indolylcyanoenones with Antibacterial Potential

A class of piperazine hybridized coumarin indolylcyanoenones was exploited as new structural antibacterial frameworks to combat intractable bacterial resistance. Bioactive assessment discovered that 4-chlorobenzyl derivative 11f showed a prominent inhibition on Pseudomonas aeruginosa ATCC 27853 with a low MIC of 1 μg/mL, which was four-fold more effective than norfloxacin. Importantly, the highly active 11f with inconspicuous hemolysis towards human red blood cells displayed quite low proneness to trigger bacterial resistance. Preliminary explorations on its antibacterial behavior disclosed that 11f possessed the ability to destroy bacterial cell membrane, leading to increased permeability of inner and outer membranes, the depolarization and fracture of membrane, and the effusion of intracellular components. Furthermore, bacterial oxidative stress and metabolic turbulence aroused by 11f also accelerated bacterial apoptosis. In particular, 11f could not only effectively inset into DNA, but also bind with DNA gyrase through forming supramolecular complex, thereby affecting the biological function of DNA. The above findings of new piperazine hybridized coumarin indolylcyanoenones provided an inspired possibility for the treatment of resistant bacterial infections.

Tackling multidrug-resistant Staphylococcus aureus by natural products and their analogues acting as NorA efflux pump inhibitors

Staphylococcus aureus (S. aureus) is a pathogen responsible for various community and hospital-acquired infections with life-threatening complications like bacteraemia, endocarditis, meningitis, liver abscess, and spinal cord epidural abscess. Antibiotics have been used to treat microbial infections since the introduction of penicillin in 1940. In recent decades, the abuse and misuse of antibiotics in humans, animals, plants, and fungi, including the treatment of non-microbial diseases, have led to the rapid emergence of multidrug-resistant pathogens with increased virulence. Bacteria have developed several complementary mechanisms to avoid the effects of antibiotics. These mechanisms include chemical transformations and enzymatic inactivation of antibiotics, modification of antibiotics' target site, and reduction of intracellular antibiotics concentration by changes in membrane permeability or by the overexpression of efflux pumps (EPs). The strategy to check antibiotic resistance includes synthesis of the antibiotic analogues, or antibiotics are given in combination with the adjuvant. The inhibitors of multidrug EPs are considered promising alternative therapeutic options with the potential to revive the effects of antibiotics and reduce bacterial virulence. Natural products played a vital role in drug discovery and significantly contributed to the area of infectious diseases. Also, natural products provide lead compounds that sometimes need modification based on structural and biological properties to meet the drug criteria. This review discusses natural products and their derived compounds as NorA efflux pump inhibitors (EPIs).

Glabridin Inhibits Aspergillus fumigatus Growth and Alleviate Inflammation Mediated by Dectin-2 and NLRP3 Inflammasome

PURPOSE

The research was used to uncover the mechanism of glabridin in Aspergillus fumigatus keratitis in anti-fungus and anti-inflammation.

METHODS

In vitro, RAW 264.7 cells were infected with A. fumigatus with incubation of glabridin in different concentrations. Real-time quantitative polymerase chain reaction (RT‑qPCR), Western blot, and enzyme-linked immunosorbent assay (ELISA) were used to assess the inflammatory severe and alternation with the intervention of Dectin-2 siRNA and glabridin. In vivo, A. fumigatus keratitis mouse models were established by spore intra-stromal injection and treated with glabridin or PBS. And disease scores, inflammatory mediators, and periodic acid-schiff (PAS) staining were exhibited to demonstrate the therapeutic efficiency of glabridin in vivo. Morphological interference assay monitored fungal germination. Scanning and transmission electron microscopy were used to observe the growth of fungi.

RESULTS

In RAW 264.7 cells and mouse keratitis models, noncytotoxic 16 μg/mL glabridin showed significant inhibition in the expression of Dectin-2, NLRP3, Caspase-1, IL-1β, and TNF-α after A. fumigatus infection, almost similar to the intervention of Dectin-2 siRNA. PAS staining illustrated the reduced hyphal distribution in cornea stroma with glabridin treatment. Glabridin remarkably inhibited A. fumigatus growth through delaying germination and disrupting the integrity of the hyphae membrane.

CONCLUSION

Glabridin plays an anti-inflammatory role in A. fumigatus challenge via suppression of the Dectin-2 and NLRP3 inflammasome, and plays an anti-fungal role through delaying germination and changing the hyphal integrity.KEY MESSAGESGlabridin plays an anti-inflammatory role in A. fumigatus infection of RAW264.7 cells in a concentration-dependent manner and through Dectin-2 mediation.Glabridin decreases fungal distribution and inflammation in mouse A. fumigatus keratitis.Glabridin inhibits A. fumigatus growth by delaying germination and disrupting cellular structure in vitro.

Review on the Diverse Biological Effects of Glabridin

Glabridin is a prenylated isoflavan from the roots of Glycyrrhiza glabra Linne and has posed great impact on the areas of drug development and medicine, due to various biological properties such as anti-inflammation, anti-oxidation, anti-tumor, anti-microorganism, bone protection, cardiovascular protection, neuroprotection, hepatoprotection, anti-obesity, and anti-diabetes. Many signaling pathways, including NF-κB, MAPK, Wnt/β-catenin, ERα/SRC-1, PI3K/AKT, and AMPK, have been implicated in the regulatory activities of glabridin. Interestingly, glabridin has been considered as an inhibitor of tyrosinase, P-glycoprotein (P-gp), and CYP2E1 and an activator of peroxisome proliferator-activated receptor γ (PPARγ), although their molecular regulating mechanisms still need further investigation. However, poor water solubility and low bioavailability have greatly limited the clinical applications of glabridin. Hopefully, several effective strategies, such as nanoemulsions, microneedles, and smartPearls formulation, have been developed for improvement.

Licorice as a herbal extract in periodontal therapy

Periodontal disease is caused by specific pathogens which results in inflammation of the tooth-supporting structures and subsequently causes the continued breakdown of alveolar bone and periodontal ligament. Licorice (Glycyrrhiza glabra) is a perennial herb with substantial medicinal value. Licorice extract is derived from dried, unpeeled stolons and roots of Glycyrrhiza uralensis and G. glabra. The bioactive ingredients in licorice extract such as glycyrrhizin, licoricidin, glabridin, licochalcone A, and licorisoflavan A have anti-inflammatory, antimicrobial, and anti-adherence effects that are beneficial against periodontal disease. Since periodontal disease has a complex etiology that includes the host response and microorganisms, licorice phytochemicals offer a therapeutic advantage due to their dual functionality. The aim of this review was to enumerate the bioactive compounds present in herbal licorice extract and to elucidate the beneficial effects of licorice and its derivatives in periodontal therapy. Literature review and clinical trials evaluating the effect of licorice on periodontopathogens and periodontal disease are included in this article.

Licorice as a herbal extract in periodontal therapy

Periodontal disease is caused by specific pathogens which results in inflammation of the tooth-supporting structures and subsequently causes the continued breakdown of alveolar bone and periodontal ligament. Licorice (Glycyrrhiza glabra) is a perennial herb with substantial medicinal value. Licorice extract is derived from dried, unpeeled stolons and roots of Glycyrrhiza uralensis and G. glabra. The bioactive ingredients in licorice extract such as glycyrrhizin, licoricidin, glabridin, licochalcone A, and licorisoflavan A have anti-inflammatory, antimicrobial, and anti-adherence effects that are beneficial against periodontal disease. Since periodontal disease has a complex etiology that includes the host response and microorganisms, licorice phytochemicals offer a therapeutic advantage due to their dual functionality. The aim of this review was to enumerate the bioactive compounds present in herbal licorice extract and to elucidate the beneficial effects of licorice and its derivatives in periodontal therapy. Literature review and clinical trials evaluating the effect of licorice on periodontopathogens and periodontal disease are included in this article.

An unanticipated discovery of novel naphthalimidopropanediols as potential broad-spectrum antibacterial members

Constructing a new antibacterial structural framework is an effective strategy to combat drug resistance. This work discovered a class of naphthalimidopropanediols (NIOLs) as a novel structural type of potential broad-spectrum antibacterial agents. Especially, NIOLs 9u, 12i, 15 against Staphylococcus aureus and NIOLs 9l, 13a against Pseudomonas aeruginosa showed excellent inhibitory activities, and they displayed high membrane selectivity from an electrostatic distinction on the membranes between bacteria and mammalian cells. These highly active NIOLs could effectually inhibit the bacterial growths, and relieve the resistance developments. Moreover, the facts of membrane depolarization, outer/inner membrane permeabilization and leakage of intracellular materials, demonstrated that these NIOLs could target and destroy the S. aureus or P. aeruginosa membranes. In particular, they could disrupt the antioxidant defense systems of S. aureus or P. aeruginosa through up-regulation of reactive oxygen species. Simultaneously, they could render the metabolic inactivation of the tested strains, and eradicate the formed biofilms and efficiently kill the strains within the biofilms. The in vitro and in vivo cytotoxicity assay indicated that these compounds possessed low toxicity. These findings of novel NIOLs as potential broad-spectrum antibacterial members provided a bright hope for conquering drug resistance.

Glabridin from Glycyrrhiza glabra Possesses a Therapeutic Role against Keloid via Attenuating PI3K/Akt and Transforming Growth Factor-β1/SMAD Signaling Pathways

Glabridin (Gla) is a typical flavonoid isolated from the Glycyrrhiza glabra with various bioactivities and is a common additive in many cosmetics. In our study, we evaluated the antiscarring effect of Gla from G. glabra in a rabbit ear hyperplastic scar model. Hematoxylin and eosin staining and Masson staining were applied to determine the pathological changes and collagen fibers of scar tissue in rabbits. The results suggested that Gla could reduce rabbit ear scar hyperplasia, inhibit inflammation, and decrease collagen production. Furthermore, the in vitro cell experiments were applied to determine the effects of Gla on human keloid fibroblasts (HKFs), and we observed that Gla suppressed the HKF cells' proliferation via inducing apoptosis. Subsequently, we found that Gla reduced collagen production in HKF cells. The further molecular mechanisms investigations suggested that Gla played a therapeutic role against keloid by attenuating PI3K/Akt and TGFβ1/SMAD pathways. Our study would be beneficial for extending the applications of the known sweet plant of G. glabra.

Glabridin induces paraptosis-like cell death via ER stress in breast cancer cells

Glabridin, a polyphenolic flavonoid isolated from the root of the glycyrrhiza glabra, has been demonstrated to have anti-tumor properties in human malignancies. This study found that glabridin decreased the viability of human breast cancer MDA-MB-231 and MCF7 cells in a dose-dependent manner that was not involved in the caspase-3 cascade. Glabridin promoted the formation of extensive cytoplasmic vacuolation by increasing the expression of endoplasmic reticulum (ER) stress markers BiP, XBP1s, and CHOP. The transmission electron microscopy and fluorescence with the ER chaperon KDEL suggested that the vacuoles were derived from ER. Glabridin-induced vacuolation was blocked when protein synthesis was inhibited by cycloheximide, demonstrating that protein synthesis is crucial for this process. Furthermore, we determined that glabridin causes loss of mitochondrial membrane potential as well as the production of reactive oxygen species, both of which lead to mitochondrial dysfunction. These features are consistent with a kind of programmed cell death described as paraptosis. This work reports for the first time that glabridin could induce paraptosis-like cell death, which may give new therapeutic approaches for apoptosis-resistant breast cancers.

Anti-microbial efficacy, mechanisms and druggability evaluation of the natural flavonoids

AIMS

This study was conducted to evaluate thirty-five natural flavonoids for their in vitro susceptibility against Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), Bacillus subtilis (ATCC 530) and Staphylococcus aureus (ATCC 6538) in search for the potential broad-spectrum antibiotic.

METHODS AND RESULTS

Glabridin, a natural isoflavonoids isolated from Glycyrrhiza glabra L., was identified to be highly active with MIC of 8-16 μg mL^-1 against S. aureus, B. subtilis and E. coli. By the results of docking simulation, we located the potential targets of glabridin as DNA gyrase and dihydrofolate reductase (DHFR). The subsequent DNA gyrase inhibition assays (glabridin: IC₅₀ = 0.8516 μmol L^-1 , ciprofloxacin: IC₅₀ = 0.04697 μmol L^-1 ), DHFR inhibition assays (glabridin: inhibition ratio=29%, methotrexate: inhibition ratio=45% under 100 μmol L^-1 treatment) and TUNEL confirmed that glabridin acted as DNA gyrase inhibitor and DHFR mild inhibitor, exerting bactericidal activity by blocking bacterial nucleic acid synthesis. CCK-8 and in silico calculations were also conducted to verify the low cytotoxicity and acceptable druggability of glabridin.

CONCLUSION

These findings suggest that glabridin represents the prototypical member of an exciting structural class of natural antimicrobial agents.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study reports a novel mechanism of bactericidal activity of glabridin against S. aureus.

Antibiofilm activity of phytochemicals against Enterococcus faecalis: A literature review

Enterococcus faecalis is a leading causative pathogen of recalcitrant infections affecting heart valves, urinary tract, surgical wounds and dental root canals. Its robust biofilm formation, production of virulence factors and antibiotic resistance contribute significantly to its pathogenicity in persistent infections. The decreased effectiveness of most of antibiotics in preventing and/or eradicating E. faecalis biofilms mandates the discovery of alternative novel antibiofilm agents. Phytochemicals are potential sources of antibiofilm agents due to their antivirulence activity, diversity of chemical structure and multiple mechanisms of action. In this review, we describe the phenotypic and genetic attributes that contribute to antimicrobial tolerance of E. faecalis biofilms. We illuminate the benefits of implementing the phytochemicals to tackle microbial pathogens. Finally, we report the antibiofilm activity of phytochemicals against E. faecalis, and explain their mechanisms of action. These compounds belong to different chemical classes such as terpenes, phenylpropenes, flavonoids, curcuminoids and alkaloids. They demonstrate the ability to inhibit the formation of and/or eradicate E. faecalis biofilms. However, the exact mechanisms of action of most of these compounds are not fully understood. Therefore, the future studies should elucidate the underlying mechanisms in detail.

Screening biofilm eradication activity of ethanol extracts from foodstuffs: potent biofilm eradication activity of glabridin, a major flavonoid from licorice (Glycyrrhiza glabra), alone and in combination with ɛ-poly-L-lysine

The ethanol extracts of 155 different foodstuffs containing medicinal plants were investigated for their biofilm eradication activities against pathogenic bacteria. A combined method of a colorimetric microbial viability assay based on reduction of a tetrazolium salt (WST-8) and a biofilm formation technique on the 96-pins of a microtiter plate lid was used to screen the biofilm eradication activities of foodstuffs. The ethanol extracts of licorice (Glycyrrhiza glabra) showed potent biofilm eradication activities against Streptococcus mutans, Staphylococcus aureus, and Porphyromonas gingivalis. Among the antimicrobial constituents in licorice, glabridin had the most potent eradication activities against microbial biofilms. The minimum biofilm eradication concentration of glabridin was 25-50 μg/ml. Furthermore, the combination of glabridin with ɛ-poly-L-lysine, a food additive, could result in broad biofilm eradication activities towards a wide variety of bacteria associated with infection, including Escherichia coli and Pseudomonas aeruginosa.

An unanticipated discovery towards novel naphthalimide corbelled aminothiazoximes as potential anti-MRSA agents and allosteric modulators for PBP2a

Available therapeutic strategies are urgently needed to conquer multidrug resistance of MRSA. A visible effort was guided towards the advancement of novel antibacterial framework of naphthalimide corbelled aminothiazoximes, and desired to assert some insight on the conjunction of individual pharmacophore with distinct biological activities and unique action mechanism. Preliminary assessment displayed that dimethylenediamine derivative 13d presented a wonderful inhibition on MRSA (MIC = 0.5 μg/mL), and showed excellent membrane selectivity (HC₅₀ > 200 μg/mL) from an electrostatic distinction of the electronegative bacterial membranes and the electroneutral mammalian membranes. Moreover, 13d could effectually relieve the development of MRSA resistance. Investigations into explaining the mechanism of anti-MRSA disclosed that 13d displayed strong lipase affinity, which facilitated its permeation into cell membrane, causing membrane depolarization, leakage of cytoplasmic contents and lactate dehydrogenase (LDH) inhibition. Meanwhile, 13d could exert interaction with DNA to hinder biological function of DNA, and disrupt the antioxidant defense system of MRSA through up-regulation of ROS subjected the strain to oxidative stress. In particular, the unanticipated mechanism for naphthalimide corbelled aminothiazoximes that 13d could suppress the expression of PBP2a by inducing allosteric modulation of PBP2a and triggering the open of the active site, was discovered for the first time. These findings of naphthalimide corbelled aminothiazoximes as a small-molecule class of anti-MRSA agents held promise in strategies for treatment of MRSA infections.

Wound healing potential of licorice extract in rat model: Antioxidants, histopathological, immunohistochemical and gene expression evidences

Wound healing is a public health concern. Licorice gained a great attention for its antioxidant and anti-inflammatory properties which expand its valuable effects as a herbal medicine. In this study, we pointed out to the wound healing potential and the mechanism by which licorice alcoholic extract can modulate cutaneous wound healing through immune, antioxidant, histopathological, immunohistochemical (IHC) and molecular studies. 24 Wister rats were assigned into 3 groups (n = 8 each); control group, topical and oral supplied groups. Licorice extract administration significantly increased total and differential leucocyte counts, phagocytic activity of neutrophils, antioxidant biomarkers as superoxide dismutase (SOD), glutathione peroxidase activities (GPx) and reduced glutathione (GSH) content with a notable reduction in oxidative stress marker malondialdehyde (MDA). Moreover, histopathological findings detected complete re-epithelialization with increasing collagen synthesis while IHC results revealed a significant enhancement in the expression of α-SMA, PDGFR-α, FGFR1 and Cytokeratin 14 in licorice treated groups compared with the control group. Licorice extract supplementation accelerated wound healing by increasing angiogenesis and collagen deposition through up-regulation of bFGF, VEGF and TGF-β gene expression levels compared with the control group. UPLC-PDA-MS/MS aided to authenticate the studied Glycyrrihza species and recognized 101 potential constituents that may be responsible for licorice-exhibited potentials. Based on our observations we concluded that licorice enhanced cutaneous wound healing via its free radical-scavenging potential, potent antioxidant activities, and anti-inflammatory actions. Therefore, licorice could be used as a potential alternative therapy for wound injury which could overcome the associated limitations of modern therapeutic products.

Inhibition of heme detoxification pathway in malaria parasite by 3-hydroxy-11-keto-β-boswellic acid isolated from Boswellia serrata

Malaria eradication is still a major global health problem in developing countries, which has been of more concern ever since the malaria parasite has developed resistance against frontline antimalarial drugs. Historical evidence proves that the plants possess a major resource for the development of novel anti-malarial drugs. In the present study, the bioactivity guided fractionation of the oleogum-resin of Boswellia serrata Roxb. yielded the optimum activity in the ethyl acetate fraction with an IC₅₀ of 22 ± 3.9 μg/mL and 26.5 ± 4.5 μg/mL against chloroquine sensitive (NF54) and resistant (K1) strains of Plasmodium falciparum respectively. Further, upon fractionation, the ethyl acetate fraction yielded four major compounds, of which 3-Hydroxy-11-keto-β-boswellic acid (KBA) was found to be the most potent with IC₅₀ values 4.5 ± 0.60 µg/mL and 6.25 ± 1.02 μg/mL against sensitive and resistant strains respectively. KBA was found to inhibit heme detoxification pathways, one of the most common therapeutic targets, which probably lead to an increase in reactive oxygen species (ROS) and nitric oxide (NO) detrimental to P. falciparum. Further, the induced intracellular oxidative stress affected the macromolecules in terms of DNA damage, increased lipid peroxidation, protein carbonylation as well as loss of mitochondrial membrane potential. However, it did not exhibit any cytotoxic effect in VERO cells. Under in vivo conditions, KBA exhibited a significant reduction in parasitemia, retarding the development of anaemia, resulting in an enhancement of the mean survival time in Plasmodium yoelii nigeriensis (chloroquine-resistant) infected mice. Further, KBA did not exhibit any abnormality in serum biochemistry of animals that underwent acute oral toxicity studies at 2000 mg/kg body weight.

Glabridin synergy with norfloxacin induces ROS in multidrug resistant Staphylococcus aureus

Glabridin (Glb), a polyphenolic flavonoid inhibits the growth of MDRSA (Multidrug resistant S. aureus) 4627 by inducing ROS. Glb in combination with Norfloxacin (Nor) synergistically induced oxidative stress. Increased ROS/RNS levels, in particular, affected macromolecules' (DNA, lipid, protein) integrity and distorted cell morphology. We found correlation between drug-effects and up-/down-regulation of oxidative stress-related as well as MDR genes. These findings could considerably potentiate the dosing routine of Nor in combination with Glb, which holds a promising prospective as a antibacterial agent against S. aureus.

Identification of a novel antifungal backbone of naphthalimide thiazoles with synergistic potential for chemical and dynamic treatment

Aim: The high incidence and prevalence of fungal infections call for new antifungal drugs. This work was to develop naphthalimide thiazoles as potential antifungal agents. Results & methodology: These compounds showed significant antifungal potency toward some tested fungi. Especially, naphthalimide thiazole 4h with excellent anti-Candida tropicalis efficacy possessed good hemolysis level, low toxicity and no obvious resistance. Deciphering the mechanism showed that 4h interacted with DNA and disrupted the antioxidant defense system of C. tropicalis. Compound 4h also triggered membrane depolarization, leakage of cytoplasmic contents and LDH inhibition. Simultaneously, 4h rendered metabolic inactivation and eradicated the formed biofilms of C. tropicalis. Conclusion: The multifaceted synergistic effect initiated by naphthalimide thiazoles is a reasonable treatment window for prospective development.

4-Chlorothymol Exerts Antiplasmodial Activity Impeding Redox Defense System in Plasmodium falciparum

Malaria remains one of the major health concerns due to the resistance of Plasmodium species toward the existing drugs warranting an urgent need for new antimalarials. Thymol derivatives were known to exhibit enhanced antimicrobial activities; however, no reports were found against Plasmodium spp. In the present study, the antiplasmodial activity of thymol derivatives was evaluated against chloroquine-sensitive (NF-54) and -resistant (K1) strains of Plasmodium falciparum. Among the thymol derivatives tested, 4-chlorothymol showed potential activity against sensitive and resistant strains of P. falciparum. 4-Chlorothymol was found to increase the reactive oxygen species and reactive nitrogen species level. Furthermore, 4-chlorothymol could perturb the redox balance by modulating the enzyme activity of GST and GR. 4-Chlorothymol also showed synergy with chloroquine against chloroquine-resistant P. falciparum. 4-Chlorothymol was found to significantly suppress the parasitemia and increase the mean survival time in in vivo assays. Interestingly, in in vivo assay, 4-chlorothymol in combination with chloroquine showed higher chemosuppression as well as enhanced mean survival time at a much lower concentration as compared to individual doses of chloroquine and 4-chlorothymol. These observations clearly indicate the potential use of 4-chlorothymol as an antimalarial agent, which may also be effective in combination with the existing antiplasmodial drugs against chloroquine-resistant P. falciparum infection. In vitro cytotoxicity/hemolytic assay evidently suggests that 4-chlorothymol is safe for further exploration of its therapeutic properties.

Amalgamation of in-silico, in-vitro and in-vivo approach to establish glabridin as a potential CYP2E1 inhibitor

CYP2E1 is directly or indirectly involved in the metabolism of ethanol and endogenous fatty acids but it plays a major role in the bio-activation of toxic substances that produce reactive metabolites leading to hepatotoxicity. Therefore, identification of CYP2E1 inhibitor from bioflavonoids class having useful pharmacological properties has dual benefit regarding avoidance of severe food-drug/nutraceutical-drug interaction and scope to develop a phytotherapeutics through an intended pharmacokinetic interaction.In the present study, we aimed to identify CYP2E1 inhibitor from experimental bioflavonoids which are unexplored for CYP2E1 inhibition till date using in-silico, in-vitro and in-vivo approaches.Results of in-vitro CYP2E1 inhibitory studies using CYP2E1-mediated chlorzoxazone 6-hydroxylation in human liver microsomes showed that glabridin have the highest potential than fisetin, epicatechin, nobiletin, and chrysin to inhibit CYP2E1 enzyme. Mechanistic investigations indicate that glabridin is a competitive CYP2E1 inhibitor. Molecular docking study results demonstrate that glabridin strongly interacted with the active site of human CYP2E1 enzyme. Pharmacokinetics of a CYP2E1 substrate in mice model indicates a significant alteration of chlorzoxazone and 6-hydroxychlorzoxazone plasma levels in the presence of glabridin. Further studies are needed to confirm the results at clinical level.Overall, glabridin is found to be a potential CYP2E1 inhibitor.

Phenolic Compounds Impact on Rheumatoid Arthritis, Inflammatory Bowel Disease and Microbiota Modulation

Non-communicable chronic diseases (NCDs) are nowadays the principal cause of death, especially in most industrialized nations. These illnesses have increased exponentially with the consumption of diets very high in fat and sugar, not to mention stress and physical inactivity among other factors. The potential impact of suboptimal diets on NCDs’ morbidity and mortality rates brings to the forefront the necessity for a new way of improving dietary habits. The literature provides extensive scientific work that presents evidence that phenolic compounds from diets have antioxidant, anti-inflammatory and antiproliferative activities that impact human health. Gut microbiota modulation by some phenolic compounds leads to favorable changes in abundance, diversity, and in the immune system. However, polyphenol’s limited bioavailability needs to be overcome, highlighting their application in new delivery systems and providing their health benefits in well-established ways such as health maintenance, treatment or adjuvant to conventional pharmacological treatments. In this context, novel dietary approaches, including new food supplements, have emerged to prevent diseases and preserve health.

Eleutheroside K isolated from Acanthopanax henryi (Oliv.) Harms suppresses methicillin resistance of Staphylococcus aureus

Acanthopanax (A.) henryi (Oliv.) Harms contain many bioactive compounds commonly used in traditional Chinese medicine. The objective of the present study was to investigate the antibacterial activity of the single constituent, Eleutheroside K (ETSK) isolated from the leaves of A. henryi (Oliv.) Harms, against methicillin-resistant Staphylococcus (S.) aureus (MRSA). Broth microdilution assay was used to measure the minimal inhibitory concentration (MIC) and the MIC values of ETSK against eight clinical S. aureus strains were all 50 µg ml^-1 . At sub-inhibitory concentrations, a synergistic effect between oxacillin (OXA) and ETSK was confirmed using checkerboard dilution assay and time-kill curve analysis. The bacteriostatic effect became more pronounced when ETSK was used in combination with detergent (Triton X-100) or ATPase inhibitor (N, N'-dicyclohexylcarbodiimide). According to western blot analysis, the down-regulated expression of Penicillin-binding protein 2a (PBP2a) further validated that the bacterial activity was inhibited when treated with ETSK in a dose-dependent manner. Results based on our study verified that ETSK significantly suppressed MRSA infections and emphasized the potential application of ETSK as a novel anti-MRSA natural drug.

Glabridin Averts Biofilms Formation in Methicillin-Resistant Staphylococcus aureus by Modulation of the Surfaceome

Staphylococcus aureus is an opportunistic bacterium of the human body and a leading cause of nosocomial infections. Methicillin resistant S. aureus (MRSA) infections involving biofilm lead to higher mortality and morbidity in patients. Biofilm causes serious clinical issues, as it mitigates entry of antimicrobials to reach the etiological agents. It plays an important role in resilient chronic infections which place an unnecessary burden on antibiotics and the associated costs. To combat drug-resistant infection involving biofilm, there is a need to discover potential anti-biofilm agents. In this study, activity of polyphenolic flavonoid glabridin against biofilm formation of methicillin resistant clinical isolates of S. aureus is being reported for the first time. Crystal violet assay and scanning electron microscopy evidences shows that glabridin prevents formation of cells clusters and attachment of methicillin resistant clinical isolate (MRSA 4423) of S. aureus to the surface in a dose dependent manner. Gel free proteomic analysis of biofilm matrix by LC-ESI-QTOF confirmed the existence of several proteins known to be involved in cells adhesion. Furthermore, expression analysis of cell surface proteins revealed that glabridin significantly down regulates an abundance of several surface-associated adhesins including fibronectin binding proteins (FnbA, FnbB), serine-aspartate repeat-containing protein D (SdrD), immunoglobulin-binding protein G (Sbi), and other virulence factors which were induced by extracellular glucose in MRSA 4423. In addition, several moonlighting proteins (proteins with multiple functions) such as translation elongation factors (EF-Tu, EF-G), chaperone protein (DnaK), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and pyruvate kinase (PK) were detected on the cell surface wherein their abundance was inversely proportional to surface-associated adhesins. This study clearly suggests that glabridin prevents biofilm formation in S. aureus through modulation of the cell surface proteins.

Real-Time Single-Cell Imaging Reveals Accelerating Lipid Peroxyl Radical Formation in Escherichia coli Triggered by a Fluoroquinolone Antibiotic

The formation of reactive oxygen species (ROS) induced by bactericidal antibiotics has been associated with a common, nonspecific mechanism of cellular death. Herein, we report real-time single-cell fluorescence studies on Escherichia coli stained with a fluorogenic probe for lipid peroxyl radicals showing the generation of this form of ROS when exposed to the minimum inhibitory concentration (MIC) and 10× MIC of the fluoroquinolone antibiotic ciprofloxacin (3 and 30 μM, respectively). Single-cell intensity-time trajectories show an induction period followed by an accelerating phase for cells treated with antibiotic, where initial and maximum intensity achieved following 3.5 h of incubation with antibiotic showed dose-dependent average values. A large fraction of bacteria remains viable after the studies, indicating ROS formation is occurring a priori of cell death. Punctate structures are observed, consistent with membrane blebbing. The addition of a membrane embedding lipid peroxyl radical scavenger, an α-tocopherol analogue, to the media increased the MIC of ciprofloxacin. Lipid peroxyl radical formation precedes E. coli cell death and may be invoked in a cascade event including membrane disruption and consequent cell wall permeabilization. Altogether, our work illustrates that lipid peroxidation is caused by ciprofloxacin in E. coli and suppressed by α-tocopherol analogues. Lipid peroxidation may be invoked in a cascade event including membrane disruption and consequent cell wall permeabilization. Our work provides a methodology to assess antibiotic-induced membrane peroxidation at the single-cell level; this methodology provides opportunities to explore the scope and nature of lipid peroxidation in antibiotic-induced cell lethality.

A Review: The Anti-inflammatory, Anticancer and Antibacterial Properties of Four Kinds of Licorice Flavonoids Isolated from Licorice

Plants have always been an important source of medicines for humans, and licorice is a very significant herb in the development of humans. As a traditional herb, it is widely cultivated in China, Japan, Russia, Spain and India. With the development of organic chemistry and biochemistry, various chemical ingredients extracted from licorice have been studied and identified. Among them, many chemical components were considered to have strong pharmacological activities, such as anti-inflammatory, anti-ulcer, antibacterial, anticancer and so on. Based on those reports, licorice has attracted the attention of many researchers in recent years, and they are devoted to discovering the active ingredients and mechanism of action of active compounds. Licorice flavonoids are one of the main extracts of licorice root and stem and have many potential biological properties. This paper aims to summarize the four kinds of licorice flavonoids, including liquiritigenin, isoliquiritigenin, licochalcone (including licochalcone A and licochalcone B) and glabridin, about their biological activities of anti-inflammatory, anticancer, antibacterial.

Target Based Virtual Screening of New Leads Inhibitor against Bacterial Cell Division Protein FtsZ for the Discovery of Antibacterial Agents

Background:

Staphylococus epidermidis coagulase negative and gram positive streptococci have emerged as major nosocomial pathogens associated with the infection of implanted medical devices and dandruff on human scalp. S. epidermidis filamenting temperature-sensitive mutant Z (FtsZ) gene encoded FtsZ protein that assembles at future bacterial cell division site that forms Z-ring structure. FtsZ is a tubulin homolog protein with low sequence similarity; this makes it possible to inhibit bacterial FtsZ protein without affecting the eukaryote cell division.

Objective:

In the present study, phytochemicals of Cinnamomum zeylanicum, Punica granatum and Glycyrrhiza glabra were virtually screened for their antibacterial activity against Staphylococcus epidermidis cell division protein, FtsZ.

Methods:

Molecular docking method was used to investigate new lead inhibitor against bacterial cell division protein FtsZ. SwissADME and ProTox tool were used to evaluate the toxicity of the lead molecule.

Results:

Molecular docking based screening confirmed that among 122 phytochemicals, β- sitosterol and glabrol showed the highest inhibitory activity against FtsZ. SwissADME tool showed β-sitosterol and glabrol as the ideal antibacterial agents.

Conclusion:

Structure based drug design strategy has been broadly used to optimize antimicrobial activity of small molecule/ligand against large protein receptor of disease, causing pathogens which gives a major breakthrough in pharmaceuticals industries. The molecular docking and SwissADME tool showed that β-sitosterol and glabrol may be developed to be potential topical and sublingual antibacterial agents, respectively.

Usnic acid modifies MRSA drug resistance through down-regulation of proteins involved in peptidoglycan and fatty acid biosynthesis

Multidrug‐resistant Staphylococcus aureus infections place a huge burden on the healthcare sector and the wider community. An increasing rate of infections caused by methicillin‐resistant Staphylococcus aureus (MRSA) has necessitated the development of alternative agents. We previously reported that usnic acid (UA) has activity against MRSA; here, we report the effect of UA in combination with norfloxacin on the drug resistance of MRSA clinical isolates. We observed that the combination of UA–norfloxacin significantly reduces the bacterial burden in mouse models infected with S. aureus, without causing any detectable associated toxicity. Proteomic analysis indicated that UA–norfloxacin induces oxidative stress within cells, which leads to membrane damage and inhibits metabolic activity and biosynthesis of peptidoglycan and fatty acids. Collectively, this study provides evidence that UA in combination with norfloxacin may be a potential candidate for development into a resistance‐modifying agent for the treatment of invasive MRSA infections.

This is the first report on the drug resistance‐modifying potential of usnic acid (UA) through inhibition of the multidrug resistance (MDR) efflux pump and down‐regulation of proteins involved in peptidoglycan and fatty acid biosynthesis. This compound may be helpful in the management of infection caused by MRSA through (a) lowering the prescribed amount of antibiotics, (b) decreasing MDR generation, and (c) intensifying the efficacy of antibiotics against MRSA/VRSA under both in vitro and in vivo conditions. These results may be helpful in the development of anti‐MRSA drug combinations from economical and non‐toxic natural products.

Liquorice (Glycyrrhiza glabra): A phytochemical and pharmacological review

In the last years, consumers are paying much more attention to natural medicines and principles, mainly due to the general sense that natural compounds are safe. On the other hand, there is a growing demand by industry for plants used in traditional medicine that could be incorporated in foods, nutraceuticals, cosmetics, or even pharmaceuticals. Glycyrrhiza glabra Linn. belongs to the Fabaceae family and has been recognized since ancient times for its ethnopharmacological values. This plant contains different phytocompounds, such as glycyrrhizin, 18β-glycyrrhetinic acid, glabrin A and B, and isoflavones, that have demonstrated various pharmacological activities. Pharmacological experiments have demonstrated that different extracts and pure compounds from this species exhibit a broad range of biological properties, including antibacterial, anti-inflammatory, antiviral, antioxidant, and antidiabetic activities. A few toxicological studies have reported some concerns. This review addresses all those issues and focuses on the pharmacological activities reported for G. glabra. Therefore, an updated, critical, and extensive overview on the current knowledge of G. glabra composition and biological activities is provided here in order to explore its therapeutic potential and future challenges to be utilized for the formulation of new products that will contribute to human well-being.