Enhancement of fluoride activity against Streptococcus mutans biofilms by a substance separated from Polygonum cuspidatum

The Use of Natural Bioactive Nutraceuticals in the Management of Tick-Borne Illnesses

The primary objective of this paper is to provide an evidence-based update of the literature on the use of bioactive phytochemicals, nutraceuticals, and micronutrients (dietary supplements that provide health benefits beyond their nutritional value) in the management of persistent cases of Borrelia burgdorferi infection (Lyme disease) and two other tick-borne pathogens, Babesia and Bartonella species. Recent studies have advanced our understanding of the pathophysiology and mechanisms of persistent infections. These advances have increasingly enabled clinicians and patients to utilize a wider set of options to manage these frequently disabling conditions. This broader toolkit holds the promise of simultaneously improving treatment outcomes and helping to decrease our reliance on the long-term use of pharmaceutical antimicrobials and antibiotics in the treatment of tick-borne pathogens such as Borrelia burgdorferi, Babesia, and Bartonella.

Effects of brief sodium fluoride treatments on the growth of early and mature cariogenic biofilms

Although fluoride has been widely used as a preventive agent for dental caries, the effects of fluoride on the activities of biofilms in different stages of cariogenic biofilm formation are less studied. This study was designed to investigate the antibiofilm activity of sodium fluoride during the early and mature stages of Streptococcus mutans (S. mutans) biofilm formation. S. mutans biofilms were formed on saliva-coated hydroxyapatite disks. In the early (0-46 h) and mature (46-94 h) biofilm stages, the biofilms were treated with different concentrations of fluoride (250, 500, 1000, 2000 ppm; 5 times in total, 1 min/treatment). Acidogenicity, dry weight, colony-forming units (CFUs), water-soluble/insoluble extracellular polysaccharides (EPSs), and intracellular polysaccharides were analysed, and confocal laser scanning microscopy images were obtained of the two stages of biofilms to determine antibiofilm activities of fluoride at varying concentrations during the formation of early and mature biofilms. In the early stages of cariogenic biofilm formation, test groups with all fluoride concentrations significantly inhibited the growth of S. mutans biofilms. The antibiofilm and anti-EPS formation activities of the brief fluoride treatments increased with a concentration-dependent pattern. At the mature biofilm stage, only the 2000 ppm fluoride treatment group significantly inhibited biofilm accumulation, activity, and intracellular/extracellular polysaccharide content compared with those of the control and other fluoride treatment groups. The antimicrobial effect of fluoride treatment on the growth of S. mutans biofilms was linked with the stage of cariogenic biofilm formation. The inhibition of S. mutans biofilm growth by fluoride treatment was easier in the early formation stage than in the mature stage. Fluoride treatment in the early stage of cariogenic biofilm formation may be an effective approach to controlling cariogenic biofilm development and preventing dental caries.

The pharmacology, toxicology and therapeutic potential of anthraquinone derivative emodin

Emodin (1, 3, 8-trihydroxy-6-methylanthraquinone) is a derived anthraquinone compound extracted from roots and barks of pharmaceutical plants, including Rheum palmatum, Aloe vera, Giant knotweed, Polygonum multiflorum and Polygonum cuspidatum. The review aims to provide a scientific summary of emodin in pharmacological activities and toxicity in order to identify the therapeutic potential for its use in human specific organs as a new medicine. Based on the fundamental properties, such as anticancer, anti-inflammatory, antioxidant, antibacterial, antivirs, anti-diabetes, immunosuppressive and osteogenesis promotion, emodin is expected to become an effective preventive and therapeutic drug of cancer, myocardial infarction, atherosclerosis, diabetes, acute pancreatitis, asthma, periodontitis, fatty livers and neurodegenerative diseases. This article intends to provide a novel insight for further development of emodin, hoping to reveal the potential of emodin and necessity of further studies in this field.

Effects of resveratrol on cariogenic virulence properties of Streptococcus mutans

Background

Streptococcus mutans is the principal etiological agent of human dental caries. The major virulence factors of S. mutans are acid production, acid tolerance, extracellular polysaccharide (EPS) synthesis and biofilm formation. The aim of this study is to evaluate the effect of resveratrol, a natural compound, on virulence properties of S. mutans.

Results

Resveratrol at sub-MIC levels significantly decreased acid production and acid tolerance, inhibited synthesis of water-soluble polysaccharide and water-insoluble polysaccharide, compromised biofilm formation. Related virulence gene expression (ldh, relA, gtfC, comDE) was down-regulated with increasing concentrations of resveratrol.

Conclusions

Resveratrol has an inhibitory effect on S. mutans cariogenic virulence properties and it represents a promising anticariogenic agent.

Evaluation of Natural and Botanical Medicines for Activity Against Growing and Non-growing Forms of B. burgdorferi

Lyme disease is the most common vector-borne disease in the US and Europe. Although the current recommended Lyme antibiotic treatment is effective for the majority of Lyme disease patients, about 10-20% of patients continue to suffer from persisting symptoms. There have been various anecdotal reports on the use of herbal extracts for treating patients with persisting symptoms with varying degree of improvements. However, it is unclear whether the effect of the herb products is due to their direct antimicrobial activity or their effect on host immune system. In the present study, we investigated the antimicrobial effects of 12 commonly used botanical medicines and three other natural antimicrobial agents for potential anti-Borrelia burgdorferi activity in vitro. Among them, 7 natural product extracts at 1% were found to have good activity against the stationary phase B. burgdorferi culture compared to the control antibiotics doxycycline and cefuroxime. These active botanicals include Cryptolepis sanguinolenta, Juglans nigra (Black walnut), Polygonum cuspidatum (Japanese knotweed), Artemisia annua (Sweet wormwood), Uncaria tomentosa (Cat's claw), Cistus incanus, and Scutellaria baicalensis (Chinese skullcap). In contrast, Stevia rebaudiana, Andrographis paniculata, Grapefruit seed extract, colloidal silver, monolaurin, and antimicrobial peptide LL37 had little or no activity against stationary phase B. burgdorferi. The minimum inhibitory concentration (MIC) values of Artemisia annua, Juglans nigra, and Uncaria tomentosa were quite high for growing B. burgdorferi, despite their strong activity against the non-growing stationary phase B. burgdorferi. On the other hand, the top two active herbs, Cryptolepis sanguinolenta and Polygonum cuspidatum, showed strong activity against both growing B. burgdorferi (MIC = 0.03-0.06% and 0.25-0.5%, respectively) and non-growing stationary phase B. burgdorferi. In subculture studies, only 1% Cryptolepis sanguinolenta extract caused complete eradication, while doxycycline and cefuroxime and other active herbs could not eradicate B. burgdorferi stationary phase cells as many spirochetes were visible after 21-day subculture. Further studies are needed to identify the active constituents of the effective botanicals and evaluate their combinations for more effective eradication of B. burgdorferi in vitro and in vivo. The implications of these findings for improving treatment of persistent Lyme disease are discussed.

Chemical Composition of East Asian Invasive Knotweeds, their Cytotoxicity and Antimicrobial Efficacy Against Cariogenic Pathogens: An In-Vitro Study

BACKGROUND Giant knotweeds originating from East Asia, such as Reynoutria japonica, and Reynoutria sachalinensis, and their hybrid such as Reynoutria x bohemica, are invasive plants in Europe and North America. However, R. japonica is also a traditional East Asian drug (Polygoni cuspidati rhizoma) used in Korean folk medicine to improve oral hygiene. The aim of this study was to evaluate the antibacterial activity of acetone extracts of Reynoutria species against dominant caries pathogen such as Streptococcus mutans and alternative pathogens, as well as characterize the phytochemical composition of extracts and examine their cytotoxicity. MATERIAL AND METHODS Ultrasonic extraction was used to obtain polyphenol-rich extracts. The extracts were characterized by HPLC-DAD-ESI-MS. To test bacterial viability, the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) against S. mutans, S. salivarius, S. sanguinis, and S. pyogenes were determined. The cytotoxicity of the extracts to human fibroblasts derived from gingiva was evaluated using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. RESULTS The R. japonica extract had the highest bacteriostatic and bactericidal activity against pathogens causing caries, mainly dominant caries pathogen S. mutans (mean MIC 1000 μg/mL and MBC 2000 μg/mL), which was most likely associated with a higher content of stilbene aglycons and anthraquinone aglycons in the extract. Moreover, the R. japonica extract demonstrated the lowest cytotoxic effect on human fibroblasts and exhibited cytotoxic activity only at the concentration causing the death of all S. mutans. CONCLUSIONS The results indicate that the R. japonica acetone extract can be considered as a natural, antimicrobial agent for caries control.

Inhibition of Streptococcus mutans Biofilms by the Natural Stilbene Piceatannol Through the Inhibition of Glucosyltransferases

Removal of oral biofilms involves the use of broad-spectrum antimicrobials, which eradicate both pathogenic and protective oral commensal species. Ideal therapeutics for dental caries should be able to selectively inhibit pathogenic biofilms caused by Streptococcus mutans. S. mutans extracellular glucosyltransferases (Gtfs), particularly GtfB and GtfC, synthesize predominantly water-insoluble glucans, which contribute to the structural scaffold of biofilms. The lead stilbene identified through our docking study against the catalytic domain of GtfC is a natural product known as piceatannol, which inhibited S. mutans biofilm formation in a dose-dependent manner, with considerable selectivity over growth inhibition of S. mutans and commensal streptococci. Binding kinetic analysis of piceatannol was performed using Octet RED against both GtfB and GtfC, which produced low micromolar K_D values. Piceatannol inhibited S. mutans colonization in an in vivo drosophila model and a rat model of dental caries.

Effect of brief periodic fluoride treatments on the virulence and composition of a cariogenic biofilm

The present study investigated the effect of periodic 1-min fluoride treatments on Streptococcus mutans biofilms and then determined the relationship between anti-biofilm activity, treatment frequency, and fluoride concentration using a linear-fitting procedure. S. mutans biofilms were periodically treated (1-min/treatment) with fluoride during biofilm formation and analyzed using microbiological methods, confocal microscopy, and real-time PCR. The results indicated that reductions in the dry weight and acidogenicity of biofilms due to periodic fluoride treatment occurred in a concentration dependent manner. The reduction in dry weight without affecting bacterial cell viability was observed mainly due to the inhibitory effect of fluoride on gtfB and gtfC gene expression, which suppresses EPS production and avoids reduction of the pH below the critical point on the tooth surface. This study suggests that brief periodic exposure to appropriate fluoride concentrations through mouthwashes and toothpastes may affect the virulence and composition of cariogenic biofilms and subsequently prevent dental caries.

Influence of fluoride on the bacterial composition of a dual-species biofilm composed of Streptococcus mutans and Streptococcus oralis

Despite the widespread use of fluoride for the prevention of dental caries, few studies have demonstrated the effects of fluoride on the bacterial composition of dental biofilms. This study investigated whether fluoride affects the proportion of Streptococcus mutans and S. oralis in mono- and dual-species biofilm models, via microbiological, biochemical, and confocal fluorescence microscope studies. Fluoride did not affect the bacterial count and bio-volume of S. mutans and S. oralis in mono-species biofilms, except for the 24-h-old S. mutans biofilms. However, fluoride reduced the proportion and bio-volume of S. mutans but did not decrease those of S. oralis during both S. oralis and S. mutans dual-species biofilm formation, which may be related to the decrease in extracellular polysaccharide formation by fluoride. These results suggest that fluoride may prevent the shift in the microbial proportion to cariogenic bacteria in dental biofilms, subsequently inhibiting the cariogenic bacteria dominant biofilm formation.

Biofilms as "Connectors" for Oral and Systems Medicine: A New Opportunity for Biomarkers, Molecular Targets, and Bacterial Eradication

Oral health and systems medicine are intimately related but have remained, sadly, as isolated knowledge communities for decades. Are there veritable connector knowledge domains that can usefully link them together on the critical path to biomarker research and “one health”? In this context, it is noteworthy that bacteria form surface-attached communities on most biological surfaces, including the oral cavity. Biofilm-forming bacteria contribute to periodontal diseases and recent evidences point to roles of these bacteria in systemic diseases as well, with cardiovascular diseases, obesity, and cancer as notable examples. Interestingly, the combined mass of microorganisms such as bacteria are so large that when we combine all plants and animals on earth, the total biomass of bacteria is still bigger. They literally do colonize everywhere, not only soil and water but our skin, digestive tract, and even oral cavity are colonized by bacteria. Hence efforts to delineate biofilm formation mechanisms of oral bacteria and microorganisms and the development of small molecules to inhibit biofilm formation in the oral cavity is very timely for both diagnostics and therapeutics. Research on biofilms can benefit both oral and systems medicine. Here, we examine, review, and synthesize new knowledge on the current understanding of oral biofilm formation, the small molecule targets that can inhibit biofilm formation in the mouth. We suggest new directions for both oral and systems medicine, using various omics technologies such as SILAC and RNAseq, that could yield deeper insights, biomarkers, and molecular targets to design small molecules that selectively aim at eradication of pathogenic oral bacteria. Ultimately, devising new ways to control and eradicate bacteria in biofilms will open up novel diagnostic and therapeutic avenues for oral and systemic diseases alike.

Drug resistance of bacterial dental biofilm and the potential use of natural compounds as alternative for prevention and treatment

Oral diseases, such as dental caries and periodontal disease are directly linked with the ability of bacteria to form biofilm. The development of dental caries involves acidogenic and aciduric Gram-positive bacteria colonizing the supragingival biofilm (Streptococcus, Lactobacillus and Actinomycetes). Periodontal diseases have been linked to anaerobic Gram-negative bacteria forming a subgingival plaque (Porphyromonas gingivalis, Actinobacillus, Prevotella and Fusobacterium). Cells embedded in biofilm are up to 1000-fold more resistant to antibiotics compared to their planctonic ones. Several mechanisms have been proposed to explain biofilms drug resistance. Given the increased bacterial resistance to antibiotics currently used in dentistry, a great importance is given to natural compounds for the prevention of oral bacterial growth, adhesion and colonization. Over the past decade, interest in drugs derived from medicinal plants has markedly increased. It has been well documented that medicinal plants and natural compounds confer considerable antibacterial activity against various microorganisms including cariogenic and periodontal pathogens. This paper provides a review of the literature focusing on the studies on (i) biofilm in the oral cavity, (ii) drug resistance of bacterial biofilm and (iii) the potential use of plant extracts, essential oils and natural compounds as biofilm preventive agents in dentistry, involving their origin and their mechanism of biofilm inhibition.

Effects of combined oleic acid and fluoride at sub-MIC levels on EPS formation and viability of Streptococcus mutans UA159 biofilms

Despite the widespread use of fluoride, dental caries, a biofilm-related disease, remains an important health problem. This study investigated whether oleic acid, a monounsaturated fatty acid, can enhance the effect of fluoride on extracellular polysaccharide (EPS) formation by Streptococcus mutans UA159 biofilms at sub-minimum inhibitory concentration levels, via microbiological and biochemical methods, confocal fluorescence microscopy, and real-time PCR. The combination of oleic acid with fluoride inhibited EPS formation more strongly than did fluoride or oleic acid alone. The superior inhibition of EPS formation was due to the combination of the inhibitory effects of oleic acid and fluoride against glucosyltransferases (GTFs) and GTF-related gene (gtfB, gtfC, and gtfD) expression, respectively. In addition, the combination of oleic acid with fluoride altered the bacterial biovolume of the biofilms without bactericidal activity. These results suggest that oleic acid may be useful for enhancing fluoride inhibition of EPS formation by S. mutans biofilms, without killing the bacterium.

Withania somnifera attenuates acid production, acid tolerance and extra-cellular polysaccharide formation of Streptococcus mutans biofilms

Withania somnifera (Ashwagandha) is a plant of the Solanaceae family. It has been widely used as a remedy for a variety of ailments in India and Nepal. The plant has also been used as a controlling agent for dental diseases. The aim of the present study was to evaluate the activity of the methanol extract of W. somnifera against the physiological ability of cariogenic biofilms and to identify the components of the extract. To determine the activity of the extract, assays for sucrose-dependent bacterial adherence, glycolytic acid production, acid tolerance, and extracellular polysaccharide formation were performed using Streptococcus mutans biofilms. The viability change of S. mutans biofilms cells was also determined. A phytochemical analysis of the extract was performed using TLC and LC/MS/MS. The extract showed inhibitory effects on sucrose-dependent bacterial adherence (≥ 100 μg/ml), glycolytic acid production (≥ 300 μg/ml), acid tolerance (≥ 300 μg/ml), and extracellular polysaccharide formation (≥ 300 μg/ml) of S. mutans biofilms. However, the extract did not alter the viability of S. mutans biofilms cells in all concentrations tested. Based on the phytochemical analysis, the activity of the extract may be related to the presence of alkaloids, anthrones, coumarines, anthraquinones, terpenoids, flavonoids, and steroid lactones (withanolide A, withaferin A, withanolide B, withanoside IV, and 12-deoxy withastramonolide). These data indicate that W. somnifera may be a potential agent for restraining the physiological ability of cariogenic biofilms.

Identification of linoleic acid, a main component of the n-hexane fraction from Dryopteris crassirhizoma, as an anti-Streptococcus mutans biofilm agent

Dryopteris crassirhizoma is a semi-evergreen plant. Previous studies have shown the potential of this plant as an agent for the control of cariogenic biofilms. In this study, the main antibacterial components of the plant were identified by correlating gas chromatography-mass spectrometry data with the antibacterial activity of chloroform and n-hexane fractions and then evaluating the activity of the most potent antibacterial component against Streptococcus mutans UA159 biofilms. The most potent antibacterial component was linoleic acid, a main component of the n-hexane fraction. Linoleic acid reduced viability in a dose dependent manner and reduced biofilm accumulation during initial and mature biofilm formation. Furthermore, when the biofilms were briefly treated with linoleic acid (10 min/treatment, a total of six times), the dry weight of the biofilms was significantly diminished. In addition, the anti-biofilm activity of the n-hexane fraction was similar to that of linoleic acid. These results suggest that the n-hexane fraction of D. crassirhizoma and linoleic acid may be useful for controlling cariogenic biofilms.

A Review of the Pharmacological Effects of the Dried Root of Polygonum cuspidatum (Hu Zhang) and Its Constituents

Traditional Chinese medicine (TCM) has been widely used in China for thousands of years to treat and prevent diseases. TCM has been proven safe and effective, and it is being considered as one of the important types of complementary and alternative medicine and receives increasing attention worldwide. The dried root of Polygonum cuspidatum Sieb. et Zucc. (also known as “Hu Zhang” in Chinese) is one of the medicinal herbs listed in the Pharmacopoeia of the People's Republic of China. Hu Zhang is widely distributed in the world. It can be found in Asia and North America and is used as folk medicine in countries such as Japan and Korea. In China, Hu Zhang is usually used in combination with other TCM herbs. The therapeutic uses of those Hu Zhang-containing TCM prescriptions or formulations are for treating cough, hepatitis, jaundice, amenorrhea, leucorrhea, arthralgia, burns and snake bites. Recent pharmacological and clinical studies have indicated that Hu Zhang has antiviral, antimicrobial, anti-inflammatory, neuroprotective, and cardioprotective functions. This review gives a summary of the reported therapeutic effects of the active compounds and the different extracts of Hu Zhang.