Reduction of bacterial volatile sulfur compound production by licoricidin and licorisoflavan A from licorice

Anti-cariogenic potential and pharmacokinetics of Licorice and Xylitol infused chewing gum

Background

Dental caries remains a global health challenge despite advancements in prevention. Traditional approaches focus on mechanical plaque removal and fluoride use, but innovative, non-invasive solutions are increasingly sought. Chewing gum, as a delivery system for bioactive ingredients, offers a convenient method for improving oral health. Xylitol, licorice, and lemon balm, known for their anti-cariogenic and antimicrobial properties, were incorporated into a novel chewing gum to evaluate its potential in preventing caries.

Methods

The chewing gum was formulated using beeswax, glycerin monostearate, xanthan gum, xylitol, lemon balm, and licorice. Physicochemical properties were assessed through Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Rheological properties, including elasticity and viscosity, were analyzed to ensure optimal texture. Antimicrobial activity was evaluated using the Minimum Inhibitory Concentration (MIC) method against key cariogenic bacteria, while flavor dynamics and in-silico docking and ADMET analysis provided additional insights.

Results

FTIR and XRD confirmed the successful integration of bioactive components and an amorphous matrix structure, promoting controlled release and stability. Antimicrobial assays showed the gum's effectiveness against Streptococcus mutans (MIC 0.20 mg/mL), with varying efficacy against other pathogens. Rheological analysis revealed xanthan gum as a key contributor to elasticity and viscosity, ensuring chewability and stability. Flavor release dynamics highlighted prolonged taste perception, with licorice providing sustained intensity. In-silico analysis supported the bioavailability and favorable pharmacokinetics of the ingredients.

Conclusion

This novel chewing gum demonstrates significant potential as an anti-cariogenic product with a balanced formulation of functional, structural, and sensory properties. Future research, including clinical trials and consumer testing, will be essential to optimize its effectiveness and marketability, addressing the demand for user-friendly oral health solutions.

The Power of Licorice (Radix glycyrrhizae) to Improve Oral Health: A Comprehensive Review of Its Pharmacological Properties and Clinical Implications

Licorice (Radix glycyrrhizae) is a plant root extract widely used in various applications, including cosmetics, food supplements, and traditional medicine. It has a long history of medicinal use in different cultures due to its diverse pharmacological properties. Licorice has traditionally been used for treating gastrointestinal problems, respiratory infections, cough, bronchitis, arthritis, and skin conditions. In recent years, the potential therapeutic benefits of licorice for oral health have gained significant interest. This paper aims to provide a comprehensive review of the effects of licorice extracts and their bioactive components on common oral diseases such as dental caries, periodontitis, halitosis, candidiasis, and recurrent aphthous ulcers. The chemical composition of licorice has shown the presence of several bioactive compounds such as glycyrrhizin, glabridin, isoliquiritigenin (ISL), and licochalcone exhibiting various pharmacological activities, including anti-inflammatory, antimicrobial, antioxidative, and immunomodulatory effects. Interestingly, in certain patients, licorice has shown a promising potential to inhibit the spread of viruses, prevent biofilm formation, reduce inflammation, boost immune responses, alleviate pain, and exert antioxidative effects. In this review, we provide a brief overview of the current understanding of licorice's therapeutic benefits in the treatment of oral ailments, emphasising its potential as an alternative treatment option for oral diseases. Further research is warranted to explore its efficacy, safety, and clinical applications using placebo-controlled clinical trials.

Lactobacillus paracasei ET-22 and derived postbiotics reduce halitosis and modulate oral microbiome dysregulation - a randomized, double-blind placebo-controlled clinical trial

Oral microbial dysbiosis is the primary etiologic factor for halitosis and may be the critical preventive target for halitosis. This study included randomized controlled trials (RCTs) assessing the effects of Lactobacillus paracasei ET-22 live and heat-killed bacteria on halitosis and the related oral microbiome. 68 halitosis subjects were divided into placebo, ET-22 live (ET-22.L) and ET-22 heat-killed (ET-22.HK) groups. Subjects took different lozenges three times a day for 4 weeks and underwent saliva collection and assessment of breath volatile sulfur compound (VSC) levels at the beginning and end of the intervention. Salivary volatile organic compounds were measured using HS-SPME-GC/MS, and the microbiome profile was determined by 16S rRNA gene amplicon sequencing. A positive decrease in breath volatile sulfur compound (VSC) levels was observed in the means of both ET-22.L and ET-22.HK groups after 4 weeks of intervention, being more marked in the ET-22.L group (p = 0.0148). Moreover, ET-22.L and ET-22.HK intervention remarkably changed the composition of total salivary volatile organic compounds (VOCs) and aroma-active VOCs. Key undesirable VOCs, such as indole, pyridine, nonanoic acid, benzothiazole, and valeric acid, were significantly reduced. Meanwhile, ET-22.L or ET-22.HK also altered the taxonomic composition of the salivary microbiome. The halitosis pathogens Rothia and Streptococcus were significantly reduced in the ET-22.HK group and the pathogenic Solobacterium and Peptostreptococcus were significantly inhibited in the ET-22.L group. Collectively, our study suggests that both ET-22.L and ET-22.HK can significantly inhibit the production of undesirable odor compounds in subjects with halitosis, which may be related to the changes of the oral microbiome.

Evaluation of the antibacterial activity of Elsholtzia ciliate essential oil against halitosis-related Fusobacterium nucleatum and Porphyromonas gingivalis

The broad-spectrum antimicrobial activity of Elsholtzia ciliate essential oil (ECO) has been previously reported, but its effectiveness against halitosis-causing bacteria such as Fusobacterium nucleatum and Porphyromonas gingivalis is not well understood. In this study, we investigated the bacteriostatic activity of ECO against planktonic cells and biofilms of F. nucleatum and P. gingivalis, as well as its ability to inhibit bacterial metabolism and production of volatile sulfur compounds (VSCs) at sub-lethal concentrations. Our findings revealed that ECO exhibited comparable activities to chlorhexidine against these oral bacteria. Treatment with ECO significantly reduced the production of VSCs, including hydrogen sulfide, dimethyl disulfide, and methanethiol, which are major contributors to bad breath. As the major chemical components of ECO, carvacrol, p-cymene, and phellandrene, were demonstrated in vitro inhibitory effects on F. nucleatum and P. gingivalis, and their combined use showed synergistic and additive effects, suggesting that the overall activity of ECO is derived from the cumulative or synergistic effect of multiple active components. ECO was found to have a destructive effect on the bacterial cell membrane by examining the cell morphology and permeability. Furthermore, the application of ECO induced significant changes in the bacterial composition of saliva-derived biofilm, resulting in the elimination of bacterial species that contribute to halitosis, including Fusobacterium, Porphyromonas, and Prevotella. These results provide experimental evidence for the potential clinical applications of ECOs in the prevention and treatment of halitosis.

Green Alternatives as Antimicrobial Agents in Mitigating Periodontal Diseases: A Narrative Review

Periodontal diseases and dental caries are the most common infectious oral diseases impacting oral health globally. Oral cavity health is crucial for enhancing life quality since it serves as the entranceway to general health. The oral microbiome and oral infectious diseases are strongly correlated. Gram-negative anaerobic bacteria have been associated with periodontal diseases. Due to the shortcomings of several antimicrobial medications frequently applied in dentistry, the lack of resources in developing countries, the prevalence of oral inflammatory conditions, and the rise in bacterial antibiotic resistance, there is a need for reliable, efficient, and affordable alternative solutions for the prevention and treatment of periodontal diseases. Several accessible chemical agents can alter the oral microbiota, although these substances also have unfavorable symptoms such as vomiting, diarrhea, and tooth discoloration. Natural phytochemicals generated from plants that have historically been used as medicines are categorized as prospective alternatives due to the ongoing quest for substitute products. This review concentrated on phytochemicals or herbal extracts that impact periodontal diseases by decreasing the formation of dental biofilms and plaques, preventing the proliferation of oral pathogens, and inhibiting bacterial adhesion to surfaces. Investigations examining the effectiveness and safety of plant-based medicines have also been presented, including those conducted over the past decade.

Induction of immunogenic cell death effect of licoricidin in cervical cancer cells by enhancing endoplasmic reticulum stress-mediated high mobility group box 1 expression

Licoricidin (LCD) is an activity compound of the roots of Glycyrrhiza uralensis, which has therapeutic efficacy, including anti-virus, anti-cancer, and enhanced immunity in Traditional Chinese Medicine. Herein, this study aimed to clarify the effect of LCD on cervical cancer cells. In the present study, we found that LCD significantly inhibited cell viability via inducing cell apoptosis and companies with cleaved-PARP protein expression and caspase-3/-9 activity. Cell viability was markedly reversed these effects by pan-caspase inhibitor Z-VAD-FMK treatment. Furthermore, we showed that LCD-induced ER (endoplasmic reticulum) stress triggers upregulating the protein level of GRP78 (Bip), CHOP, and IRE1α, and subsequently confirmed the mRNA level by quantitative real-time polymerase chain reaction. In addition, LCD exhibited the release of danger-associated molecular patterns from cervical cancer cells, such as the release of high-mobility group box 1 (HMGB1), secretion of ATP, and exposure of calreticulin (CRT) on the cell surface, which led to immunogenic cell death (ICD). These results provide a novel foundation that LCD induces ICD via triggering ER stress in human cervical cancer cells. LCD might be an ICD inducer of immunotherapy in progressive cervical cancer.

Sulfate-Reducing Bacteria in Patients Undergoing Fixed Orthodontic Treatment

OBJECTIVES

The oral microbiological environment may be implicated in the corrosion of orthodontic metals. This study aimed to examine the prevalence of sulfate-reducing bacteria (SRB) in orthodontic patients undergoing fixed appliance treatment.

METHODS

Sixty-nine orthodontic and 69 healthy non-orthodontic participants were enrolled in the study. Supragingival and subgingivaloral biofilm were collected and tested for the presence of SRB. The DNA extraction, polymerase chain reaction (PCR), and 16sRNA Sanger sequencing method was performed from the SRB-positive samples. The sequenced PCR products were analysed and compared with databases to identify the bacterial genus.

RESULTS

Amongst 69 orthodontic patients, characteristic black precipitates developed in 14, indicating the presence of iron sulfides which demonstrates the likelihood of SRB. Alternatively, 2 out of 69 showed the presence of SRB in healthy non-orthodontic participants (controls). Desulfovibrio spp was confirmed by analyses of 16sRNA sequencing, which revealed that the SRB prevalence was 20% in the examined participants with orthodontic appliances.

CONCLUSIONS

The prevalence of SRB was found to be significantly higher amongst orthodontic patients compared to non-orthodontic participants. Presence of stainless steel in the oral environment may have facilitated the colonisation of SRB.

Porphyromonas gingivalis: where do we stand in our battle against this oral pathogen?

Periodontal diseases, such as gingivitis and periodontitis, are inflammatory diseases triggered by pathogenic bacteria that lead to damage of the soft tissue and bone supporting the teeth. Amongst the identified oral periodontopathogenic bacteria, Porphyromonas gingivalis is able to enhance oral dysbiosis, which is an imbalance in the beneficial commensal and periodontal pathogenic bacteria that induces chronic inflammation. Given the critical role of oral pathogenic bacteria like P. gingivalis in the pathogenesis of periodontitis, local and/or systemic antibacterial therapy has been suggested to treat this disease, especially in its severe or refractory forms. Nevertheless, the majority of the antibacterial agents currently used for the treatment of periodontal diseases are broad-spectrum, which harms beneficial bacterial species that are critical in health, inhibit the growth of pathogenic bacteria, contribute in protecting the periodontal tissues to damage and aid in its healing. Thus, the development of more effective and specific antibacterial agents is needed to control oral pathogens in a polymicrobial environment. The strategies for the development of novel antibacterial agents include natural product isolation as well as synthetic and semi-synthetic methodologies. This review presents an overview of the periodontal diseases gingivitis and periodontitis along with current antibacterial treatment options (i.e., classes of antibacterial agents and the mechanism(s) of resistance that hinder their usage) used in periodontal diseases that specifically target oral pathogens such as P. gingivalis. In addition, to help medicinal chemists gain a better understanding of potentially promising scaffolds, this review provides an in-depth coverage of the various families of small molecules that have been investigated as potential anti-P. gingivalis agents, including novel families of compounds, repositioned drugs, as well as natural products.

Licoricidin Abrogates T-Cell Activation by Modulating PTPN1 Activity and Attenuates Atopic Dermatitis In Vivo

Licoricidin, the fifth-highest fraction among the isolated 48 molecules from Glycyrrhiza uralensis extracts, has been known as an anti-inflammatory bioactive molecule; however, few studies have shown its inhibitory effect on T-cell activation and atopic dermatitis (AD). This study examined the therapeutic potential of licoricidin in AD by modulating T-cell activation with molecular mechanisms. Licoricidin attenuated the expression of IL-2 mRNA in stimulated T cells without cytotoxicity. Because tyrosine-protein phosphatase nonreceptor type 1 was predicted to interact physically with licoricidin in T cells in silico analysis, the results of tyrosine-protein phosphatase nonreceptor type 1 activity assay and phosphorylation study predicted that licoricidin might abrogate the activity of tyrosine-protein phosphatase nonreceptor type 1 during T-cell activation. Pretreatment with licoricidin controlled the dephosphorylation of Lck on TCR-mediated stimulation. Moreover, licoricidin alleviated the symptoms of dinitrochlorobenzene- and/or mite extract-induced AD, including ear thickness and serum IgE level. Microscopic analysis also showed the effects of licoricidin on the thickness of the dermis and epidermis and infiltration of immune cells. Furthermore, mRNA levels of proinflammatory cytokines were attenuated in the ear lesions of licoricidin-treated AD mice. Therefore, licoricidin has therapeutic potential for treating AD, and its underlying mechanism involves effective modulation of T-cell activation by controlling tyrosine-protein phosphatase nonreceptor type 1 to maintain Lck phosphorylation.

Effects of the Licorice Isoflavans Licoricidin and Glabridin on the Growth, Adherence Properties, and Acid Production of Streptococcus mutans, and Assessment of Their Biocompatibility

Pharmacological studies have linked a number of human health benefits with licorice due to its anticancer, anti-inflammatory, anti-oxidant, and antimicrobial properties. The aim of this study was to investigate the effects of licoricidin and glabridin, two major licorice isoflavans, on growth and virulence properties (biofilm formation, acid production, dextran production, adherence) of the cariogenic bacterium Streptococcus mutans. Moreover, the biocompatibility of these licorice compounds was assessed in an in vitro model of oral keratinocytes. We used a broth microdilution assay to show that licoricidin and glabridin exhibit a marked antibacterial activity against S. mutans. Glabridin and, to a lesser extent, licoricidin reduced the biofilm viability of S. mutans. In addition, glabridin decreased the production of dextran by S. mutans. The two licorice isoflavans attenuated the adherence of S. mutans to a saliva-coated hydroxylapatite surface, and reduced acid production from glucose. Lastly, depending on the concentrations tested, the two licorice isoflavans showed no or low toxicity toward oral keratinocytes. Within the limitations of this study, our data suggest that licoricidin and glabridin may be promising agents for controlling dental caries.

Licoricidin improves neurological dysfunction after traumatic brain injury in mice via regulating FoxO3/Wnt/β-catenin pathway

Traumatic brain injury (TBI) is a major cause of death and disability around the world with no effective treatments currently. The present study was aimed to investigate the neuroprotective effect of licoricidin, one of the major components of licorice extract, on TBI mice and further explore the underlying mechanism. Male C57BL/6 mice were modeled by a modified weight-drop method to mimic TBI. All animals received treatment 30 min after TBI. The modified Neurological Severity Score (NSS) tests were performed at 2 h and 1-3 days after TBI. The brain edema was analyzed by dry-wet weight method. The malonaldehyde (MDA) levels and the activities of glutathione peroxidase (GSH-PX), superoxide dismutase (SOD) and catalase (CAT) were determined by Elisa. Apoptotic neurons were detected using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) immunofluorescence and the expression of apoptotic proteins were measured by western blot. Activation of the FoxO3/Wnt/β-catenin was evaluated by western blot. The results showed that treatment with licoricidin could significantly decline the NSS scores and reduce the brain edema, hence promote the recovery of neurological function in TBI mice. It also elevated the phosphorylation of p66^shc, brought down the levels of MDA, as well as antagonized the decrement in activities of GSH-PX, SOD and CAT induced by TBI. Moreover, licoricidin decreased the TUNEL positive neurons, downregulated the expression of Cyt-C, cleaved-Caspase-3, cleaved-Caspase-9 and Bax and upregulated the Bcl-2, attenuated cellular apoptosis. Licoricidin decreased the expression of FoxO3 and increased the Wnt/β-catenin in TBI mice. In conclusion, Licoricidin exerted neuroprotective effect on TBI model and the effect was possibly due to its antioxidative effect and antiapoptotic effect via regulating the FoxO3/Wnt/β-catenin pathway. Licoricidin may be a candidate drug for TBI therapy.

Therapeutic benefits of liquorice in dentistry

Oral health influences general well-being and quality of life. Oral diseases can be debilitating and are a major heath concern worldwide. Medicinal plants have been used for thousands of years for treating human diseases. Considering the emergence of multi-drug resistant pathogens and financial difficulties in developing countries, there is an urgent need for developing new antimicrobial compounds which are safe, efficient and cost effective. Liquorice also known as yashtimadhu, sweetwood or mulhatti is one such herbal remedy which has shown to have immense potential in treatment of orofacial diseases. Liquorice is rich in secondary metabolites which are used in cosmetics, foods, traditional and modern medicine. It has well known properties such as antiviral, glucocorticoid, anti-inflammatory, antioxidant, anti-ulcerative, anti-carcinogenic and many more. Liquorice extracts and liquorice bioactive ingredients such as glabridin, licoricidin, licorisoflavan A, licochalcone A, and glycyrrhizin have shown beneficial effects in preventing and treating oral diseases. This paper reviews the effects of liquorice and its constituents on oral diseases such as dental caries, periodontitis, gingivitis, candidiasis, recurrent aphthous ulcer and oral cancer and its use as a root canal medicament and summarizes the results of clinical trials that investigated the potential beneficial effects of liquorice and its constituents as a prevention and treatment modality in oral diseases. Clinical trials, case reports and review of literature evaluating the effect of liquorice on oral microorganisms and oral diseases are included. Literature pertaining to the effects of liquorice on systemic diseases have been excluded from this review of literature.

Pharmacological Effects of Glycyrrhiza spp. and Its Bioactive Constituents: Update and Review

The roots and rhizomes of various species of the perennial herb licorice (Glycyrrhiza) are used in traditional medicine for the treatment of several diseases. In experimental and clinical studies, licorice has been shown to have several pharmacological properties including antiinflammatory, antiviral, antimicrobial, antioxidative, antidiabetic, antiasthma, and anticancer activities as well as immunomodulatory, gastroprotective, hepatoprotective, neuroprotective, and cardioprotective effects. In recent years, several of the biochemical, molecular, and cellular mechanisms of licorice and its active components have also been demonstrated in experimental studies. In this review, we summarized the new phytochemical, pharmacological, and toxicological data from recent experimental and clinical studies of licorice and its bioactive constituents after our previous published review.

Green tea extract and its major constituent epigallocatechin-3-gallate inhibit growth and halitosis-related properties of Solobacterium moorei

Background

Solobacterium moorei is a volatile sulfide compound (VSC)-producing Gram-positive anaerobic bacterium that has been associated with halitosis. The aim of this study was to investigate the effects of green tea extract and its major constituent epigallocatechin-3-gallate (EGCG) on growth and several halitosis-related properties of S. moorei.

Methods

A microplate dilution assay was used to determine the antibacterial activity of green tea extract and EGCG against S. moorei. Their effects on bacterial cell membrane integrity were investigated by transmission electron microscopy and a fluorescence-based permeability assay. Biofilm formation was quantified by crystal violet staining. Adhesion of FITC-labeled S. moorei to oral epithelial cells was monitored by fluorometry. The modulation of β-galactosidase gene expression in S. moorei was evaluated by quantitative RT-PCR.

Results

The green tea extract as well as EGCG inhibited the growth of S. moorei, with MIC values of 500 and 250 μg/ml, respectively. Transmission electron microscopy analysis and a permeabilization assay brought evidence that the bacterial cell membrane was the target of green tea polyphenols. Regarding the effects of green tea polyphenols on the S. moorei colonization properties, it was found that biofilm formation on EGCG-treated surfaces was significantly affected, and that green tea extract and EGCG can cause the eradication of pre-formed S. moorei biofilms. Moreover, both the green tea extract and EGCG were found to reduce the adherence of S. moorei to oral epithelial cells. The β-galactosidase activity of S. moorei, which plays a key role in VSC production, was dose-dependently inhibited by green tea polyphenols. In addition, EGCG at ½ MIC significantly decreased the β-galactosidase gene expression.

Conclusion

Our study brought evidence to support that green tea polyphenols possess a number of properties that may contribute to reduce S. moorei-related halitosis. Therefore, these natural compounds may be of interest to be used to supplement oral healthcare products.