Major Oral Pathogens Research Articles

Selective production of two prebiotic extracellular polysaccharides from an oral probiotic lactic acid bacterium, Streptococcus salivarius SY511

Streptococcus salivarius is a lactic acid bacterium and an oral probiotic species. Growth of S. salivarius in a sucrose medium can lead to the production of exopolysaccharides (EPSs) that are potential prebiotics. However, no studies have yet examined use of this species for the selective production of high concentrations of EPSs. In this study, we isolated S. salivarius SY511 from infant feces and grew it in a sucrose medium to produce high levels of water-insoluble and water-soluble EPSs. NMR and monosaccharide analysis demonstrated that water-insoluble glucan and water-soluble levan were the two main EPSs. Batch fermentation in MRS-sucrose medium led to the efficient production of these two EPSs, and Tween 80 was a key factor that affected their differential production. In the fed-batch fermentation, 22.7 g/L of water-insoluble glucan was produced in the MRS-sucrose medium, while 24.9 g/L of levan was produced in the MRS-sucrose medium without Tween 80. Compared to S. salivarius M18, S. salivarius SY511 had higher or similar antimicrobial activity against major oral pathogens. Furthermore, the water-insoluble glucan and levan from S. salivarius SY511 had excellent prebiotic, anti-inflammatory, and antioxidant effects. Our study of S. salivarius SY511 identified a method for the selective production of two EPSs.

Modulation of myeloid-derived suppressor cell functions by oral inflammatory diseases and important oral pathogens.

The oral cavity presents a diverse microbiota in a dynamic balance with the host. Disruption of the microbial community can promote dysregulation of local immune response which could generate oral diseases. Additionally, alterations in host immune system can result in inflammatory disorders. Different microorganisms have been associated with establishment and progression of the oral diseases. Oral cavity pathogens/diseases can modulate components of the inflammatory response. Myeloid-derived suppressor cells (MDSCs) own immunoregulatory functions and have been involved in different inflammatory conditions such as infectious processes, autoimmune diseases, and cancer. The aim of this review is to provide a comprehensive overview of generation, phenotypes, and biological functions of the MDSCs in oral inflammatory diseases. Also, it is addressed the biological aspects of MDSCs in presence of major oral pathogens. MDSCs have been mainly analyzed in periodontal disease and Sjögren's syndrome and could be involved in the outcome of these diseases. Studies including the participation of MDSCs in other important oral diseases are very scarce. Major oral bacterial and fungal pathogens can modulate expansion, subpopulations, recruitment, metabolism, immunosuppressive activity and osteoclastogenic potential of MDSCs. Moreover, MDSC plasticity is exhibited in presence of oral inflammatory diseases/oral pathogens and appears to be relevant in the disease progression and potentially useful in the searching of possible treatments. Further analyses of MDSCs in oral cavity context could allow to understand the contribution of these cells in the fine-tuned balance between host immune system and microorganism of the oral biofilm, as well as their involvement in the development of oral diseases when this balance is altered.

Effects of two novel denture cleansers on multispecies microbial biofilms, stain removal and the denture surface: an in vitro study

BackgroundThe continuously increasing demand for removable denture appliances and the importance of adequate denture cleaning have led to the development of various denture cleansing products. The aim of this study was to evaluate the efficacy of two novel denture cleansing agents (GE and TM) and three commonly available cleansers (0.5% sodium hypochlorite; NaClO, 0.12% chlorhexidine gluconate; CHX, and Polident®; POL) on multispecies microbial biofilm formation, stain removal and physical properties of dentures.MethodsThe antimicrobial activities of denture cleansing agents were determined against major oral opportunistic pathogens including Streptococcus mutans, Staphylococcus aureus, Escherichia coli and Candida albicans, using time-kill assays. Multispecies microbial biofilms grown on acrylic resins for 72 h were generated to determine the antibiofilm effects of cleansing agents by confocal laser scanning microscopy (CLSM). Evaluations of the tea and coffee stain removal properties and the alterations in the physical properties of dentures were also performed. The toxicity of cleanser residues released from denture acrylics to fibroblast cells was investigated using MTT assay.ResultsAll denture cleansing agents tested could effectively kill oral bacteria and Candida albicans. Furthermore, after immersion for more than 3 h, the cleansers Polident®, GE and TM could efficiently penetrate and inhibit multispecies denture biofilms with effects similar to 10 min of immersion in 0.5% NaClO. However, immersion in 0.12% CHX for 20 min showed less antibiofilm activity. The NaClO solution had the highest efficacy for removing stains from the artificial teeth. Conversely, the CHX solution enhanced tea and coffee staining, and the teeth immersed in this solution showed clinically unacceptable colour changes (ΔE > 5.5). However, the colour differences of teeth stained and immersed in POL, GE and TM cleansers were in the clinically acceptable range. There was no significant difference among the POL, GE and TM cleansers in terms of stain removal efficacy. The cleansers GE and TM did not alter the surface roughness and colour of the materials, moreover the residues of both cleansers did not exhibit cytotoxicity.ConclusionTwo novel denture cleansing agents containing natural products, GE and TM exhibited effective antimicrobial activity, antibiofilm and stain removal capabilities without toxicity or disturbance of the physical properties of acrylics.

Oral Probiotics, Streptococcus salivarius K12 and M18, Suppress the Release of Volatile Sulfur Compounds and a Virulent Protease from Oral Bacteria: An In-Vitro Study.

To evaluate the inhibitory effects of Streptococcus salivarius K12 and M18 strains on the growth of six oral pathogens as well as their release of volatile sulfur compounds (VSCs), and whether these probiotics can inhibit the expression of arginine-specific gingipain A (RgpA), a protease secreted by Porphyromonas gingivalis. After six halitogenic oral pathogens (P. gingivalis, Treponema denticola, Tannerella forsythia, Fusobacterium nucleatum, Parvimonas micra, and Eikenella corrodens) were cultured with or without S. salivarius K12 and M18, the concentration of two VSCs was measured. Moreover, the antimicrobial activity of S. salivarius K12 and M18 against these pathogens and the suppressive effect on RgpA release by P. gingivalis were assessed. In the co-culture of S. salivarius K12 or M18 with oral pathogenic bacteria, the growth of all six oral pathogens was significantly inhibited (p < 0.01). Additionally, S. salivarius K12 and M18 had an inhibitory effect on the production of the halitogenic substances H2S and CH3SH (p < 0.01) as well as the expression of P. gingivalis RgpA. Finally, we demonstrated that the addition of only culture supernatants of the two strains K12/M18 to oral pathogen cultures was sufficient to mimic the effects of K12/M18 co-cultures upon VSCs production and protease expression. S. salivarius K12 and M18 inhibited VSC release by all six of the major oral pathogens that were assayed and reduced the expression of RgpA.

Bruksizm Varlığında ve Yokluğunda, Periodontal Sağlık ve Hastalıkta Vasküler Endotelyal Büyüme Faktörü, Hipoksi ile İndüklenebilir Faktör 1-Alfa ve Bakteriyel Plak Kompozisyonunun Değerlendirilmesi: Randomize Olmayan Klinik Çalışma

Aim: In this study, we aimed to evaluate the possible changes in hypoxia markers and bacterial compo-nents in patients with periodontitis and bruxism. Methods: Four study groups were created: 20 healthy individuals without bruxism (Group 1), 20 periodontitis patients without bruxism (Group 2), 20 healthy individuals with bruxism (Group 3), and 20 periodontitis patients with bruxism (Group 4). Plaque index, gingival index, and clinical attach-ment levels were recorded and gingival crevicular fluid (GCF) and dental plaque samples were taken. The GCF vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1-alpha (HIF-1α) levels were determined. Subgingival plaque samples were evaluated for 5 bacterial species (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, and Fu¬sobacterium nucleatum). Results: Compared to patients with periodontitis, plaque index, gingival index, and clinical attachment levels were significantly lower in healthy individuals. The GCF and serum levels of VEGF and HIF-1α were similar (p&amp;gt;0.05). The A. actinomycetemcomitans, T. denticola, and F. nucleatum counts did not differ significantly between the study groups (p&amp;gt;0.05). P. gingivalis counts were lowest in Group 1 and increased with both periodontitis and bruxism. T. forsythia counts were higher in Group 1 and Group 2 than in Group 3 and Group 4. The levels in Group 1 were lower than those in Group 2. Conclusion: Individuals with and without bruxism were found to be similar in terms of hypoxia in periodontal health and disease. However, one of the major oral pathogens, P. gingivalis, is af¬fected by the presence of bruxism, regardless of periodontitis.

Isolation and storage of Aggregatibacter actinomicetemcomitans from the subgingival plaque of patients with periodontitis

Objective: To isolate and identification Aggregatibacter actinomicetemcomitans from clinical subgingival plaques of periodontitis patients. Methods: Selective media was prepared by adding 200 ug/mL of vancomycin and 10 U/mL of bacitracin, 5% sheep blood to Wilkins Chalgren Anaerobic agar. Subgingival samples collected from patients with moderate to severe periodontitis aged 18- 35 were used to recover Aa. The colony was then identified by the MALDI-TOF method and PCR analysis. Results: The Aa was successfully cultured and stored from a clinical sample of the 12th 25 years-old patient who had moderate aggressive periodontitis. Conclusion: Aa is a major putative oral pathogen and concerned with other systemic diseases. This pure bacterial culture will be helpful for other experimental studies in dental and medical areas.

A study on the green synthesis of silver nanoparticles from Olea europaea and its activity against oral pathogens

Abstract Silver nanoparticles are applied in a variety of medical and non-medical fields due to their unique properties. Researchers are keen on synthesizing silver nanoparticles from biological sources as they are environmentally sound. Plants are a good option as they are abundant in nature and are rich in active metabolites that help in the reduction of silver ions. In this study, we have synthesized silver nanoparticles using olive fruit extract which were characterized by UV–visible spectroscopy, Fourier Transform Infrared spectroscopy (FTIR), High Resolution Scanning Electron Microscopy (HR-SEM) and zeta potential analysis which confirmed the formation of spherical, nano-sized particles. The efficacy of synthesized silver nanoparticles against the growth and biofilm formation of major oral pathogens Streptococcus mutans and Candida albicans was demonstrated. The study revealed that olive fruit extract is an excellent producer of silver nanoparticles with potential activity against oral pathogens.

An In Vitro Study on the Antimicrobial Properties of Essential Oil Modified Resin Composite against Oral Pathogens.

Modifying the composition of dental restorative materials with antimicrobial agents might induce their antibacterial potential against cariogenic bacteria, e.g., S. mutans and L. acidophilus, as well as antifungal effect on C. albicans that are major oral pathogens. Essential oils (EOs) are widely known for antimicrobial activity and are successfully used in dental industry. The study aimed at evaluating antibacterial and antifungal activity of EOs and composite resin material (CR) modified with EO against oral pathogens. Ten EOs (i.e., anise, cinnamon, citronella, clove, geranium, lavender, limette, mint, rosemary thyme) were tested using agar diffusion method. Cinnamon and thyme EOs showed significantly highest antibacterial activity against S. mutans and L. acidophilus among all tested EOs. Anise and limette EOs showed no antibacterial activity against S. mutans. All tested EOs exhibited antifungal activity against C. albicans, whereas cinnamon EO showed significantly highest and limette EO significantly lowest activity. Next, 1, 2 or 5 µL of cinnamon EO was introduced into 2 g of CR and microbiologically tested. The modified CR showed higher antimicrobial activity in comparison to unmodified one. CR containing 2 µL of EO showed the best antimicrobial properties against S. mutans and C. albicans, while CR modified with 1 µL of EO showed the best antimicrobial properties against L. acidophilus.

Mining the Proteome of Streptococcus mutans for Putative Drug Targets.

Dental caries is the most common and one of the prevalent diseases in the world. Streptococcus mutans is one of the major oral pathogens that cause dental caries by forming a biofilm on dental tissues, degrading dental enamel and consequent cavitation in the tissue. In vitro selection of drug targets is a laborious and expensive process and therefore, computational methods are preferable for target identification at the initial stage. The present research aims to find new drug targets in S. mutans by using subtractive proteomics analysis, which implements various bioinformatics tools and databases. The proteome of S. mutans UA159 was mined for novel drug targets using computational tools and databases such as: CD-HIT, BLASTP, DEG, KAAS and CELL2GO. Out of 1953 proteins of S. mutans UA159, proteins that are redundant, homologous to human and non-essential to the pathogen were eliminated. Around 178 proteins already available in drug target repositories were also eliminated. Possible functions and subcellular localization of 32 uncharacterized proteins were predicted. Substantially, 13 proteins were identified as novel drug targets in S. mutans UA159 that can be targeted by various drugs against dental caries. This study will effectuate the development of novel therapeutic agents against dental caries and other Streptococcal infections.

Endophytic Fungi, A Novel source in the treatment of Oral infections

Living organisms in nature are in constant relationship with each other. The high diversity of endophytic fungi that has been present in varied host plants contributes to the appeal of endophytic fungi for ecological studies. Bioactive secondary metabolites from endophytes represent a chemical reservoir for antibiotic, antioxidant, immune modulating, anticancer and anti-parasitic compounds. Endophytic fungal sources have proved to be promising sources of various oral infections. This chapter explores the diversity of endophytic fungi from various medicinal plants and their activity against two major oral pathogens Streptococcus mutans and Candida albicans.

Marine bromophenols as an effective inhibitor of virulent proteins (peptidyl arginine deiminase, gingipain R and hemagglutinin A) in Porphyromas gingivalis

ObjectivesPorphyromonas gingivalis, is one of the major oral pathogen that produce virulent proteins which mediate periodontal tissue inflammation and infection. Marine algae have recently gained popularity for its bioactive molecules and their oral applications. Marine bromophenols (MBs) is abundant in red algae which are reported to have wide medicinal properties. The current research primarily focuses to elucidate the bioactivity of MBs against the virulent proteins produced by P. gingivalis. Materials and methodsPotent MBs which effectively binds and inhibits the virulent proteins peptidyl arginine deiminase (PPAD), gingipain R (Rgp) and hemagglutinin A (HgA) was identified through molecular docking and molecular simulation approach. MBs were extracted from Kappaphycus alvarezii (KAB), marine red algae found in India. The efficacy of this MB was studied against P. gingivalis by employing antibacterial activity assays, gingipain assay, hemagglutination inhibition assay (HIA) and mRNA expression analysis (q RT PCR). ResultsMBs with benzene, methyl and glycosyl substitutions demonstrated significant docking score, with good stability and pharmacokinetic properties. In addition to the antibacterial activities against P. gingivalis, KAB was also found to inhibit the gingipain and hemagglutination activities. Exposure of KAB to the virulent genes in P. gingivalis resulted in low mRNA levels of these genes, which suggested the down regulation functions induced by the MBs. ConclusionBiochemical investigations revealed that KAB is a potent natural metabolite that can inhibit and control the virulent proteins produced by P. gingivalis. This study recommends future research to direct towards applicability of MBs in commercial dental products.

Inhibitory effect of probiotic lactobacilli against Streptococcus mutans and Porphyromonas gingivalis biofilms

Background: Lactobacillus reuteri and Lactobacillus casei have been proposed as probiotic bacteria that promote oral health. Objectives: The present study aimed to evaluate the in vitro effects of L. reuteri and L. casei on the biofilm formation of major oral pathogens, Streptococcus mutans and Porphyromonas gingivalis. Materials and Methods: L. casei strain Shirota and L. reuteri ATCC 55730 were isolated from the commercial products and cultured in de Man, Rogosa, and Sharpe broth. Polymerase chain reaction was used to confirm the identity of the species. S. mutans ATCC 25175 and P. gingivalis ATCC 33277 were cultured in brain–heart infusion broth and used for biofilm formation on 96-well microplate platform. The biofilms were treated with the probiotics and appropriate controls in a time-dependent experiment from 15 min to 24 h. The biofilm biomass was evaluated using crystal violet and safranin. Results: The statistical analysis showed a significant reduction in the S. mutans and P. gingivalis biofilms after treatment with the L. reuteri and L. casei probiotics at all incubation times (P < 0.05). Conclusion: The present study demonstrated the potential antibiofilm activity of L. casei strain Shirota and L. reuteri ATCC 55730 against S. mutans and P. gingivalis biofilms in vitro. The foregoing data have formed a basis for future clinical studies to evaluate the beneficial oral health effect of probiotic Lactobacilli strains.

Conserved Citrullinating Exoenzymes in Porphyromonas Species

Porphyromonas gingivalis is one of the major oral pathogens implicated in the widespread inflammatory disorder periodontitis. Moreover, in recent years, P. gingivalis has been associated with the autoimmune disease rheumatoid arthritis. The peptidylarginine deiminase enzyme of P. gingivalis (PPAD) is a major virulence factor that catalyzes the citrullination of both bacterial and host proteins, potentially contributing to production of anticitrullinated protein antibodies. Considering that these antibodies are very specific for rheumatoid arthritis, PPAD appears to be a link between P. gingivalis, periodontitis, and the autoimmune disorder rheumatoid arthritis. PPAD was thus far considered unique among prokaryotes, with P. gingivalis being the only bacterium known to produce and secrete it. To challenge this hypothesis, we investigated the possible secretion of PPAD by 11 previously collected Porphyromonas isolates from a dog, 2 sheep, 3 cats, 4 monkeys, and a jaguar with periodontitis. Our analyses uncovered the presence of secreted PPAD homologues in 8 isolates that were identified as Porphyromonas gulae (from a dog, monkeys, and cats) and Porphyromonas loveana (from sheep). In all 3 PPAD-producing Porphyromonas species, the dominant form of the secreted PPAD was associated with outer membrane vesicles, while a minor fraction was soluble. Our results prove for the first time that the citrullinating PPAD exoenzyme is not unique to only 1 prokaryotic species. Instead, we show that PPAD is produced by at least 2 other oral pathogens.

Molecular mechanisms of Porphyromonas gingivalis-host cell interaction on periodontal diseases.

SummaryPorphyromonas gingivalis (P. gingivalis) is a major oral pathogen and associated with periodontal diseases including periodontitis and alveolar bone loss. In this review, we indicate that two virulence factors, which are hemoglobin receptor protein (HbR) and cysteine proteases “gingipains”, expressed by P. gingivalis have novel functions on the pathogenicity of P. gingivalis. P. gingivalis produces three types of gingipains and concomitantly several adhesin domains. Among the adhesin domains, hemoglobin receptor protein (HbR), also called HGP15, has the function of induction of interleukin-8 (IL-8) expression in human gingival epithelial cells, indicating the possibility that HbR is associated with P. gingivalis-induced periodontal inflammation. On bacteria-host cells contact, P. gingivalis induces cellular signaling alteration in host cells. Phosphatidylinositol 3-kinase (PI3K) and Akt are well known to play a pivotal role in various cellular physiological functions including cell survival and glucose metabolism in mammalian cells. Recently, we demonstrated that gingipains attenuate the activity of PI3K and Akt, which might have a causal influence on periodontal diseases by chronic infection to the host cells from the speculation of molecular analysis. In this review, we discuss new molecular and biological characterization of the virulence factors from P. gingivalis.

Health-Associated Niche Inhabitants as Oral Probiotics: The Case of Streptococcus dentisani.

Oral diseases, including dental caries and periodontitis, are among the most prevalent diseases worldwide and develop as a consequence of a microbial dysbiosis. Several bacterial strains are being tested as potential oral health-promoting organisms, but usually they are species isolated from niches other than the site where they must exert its probiotic action, typically from fecal samples. We hypothesize that oral inhabitants associated to health conditions will be more effective than traditional, gut-associated probiotic species in key aspects such as colonization of the oral site where disease takes place or the possession of oral health promoting functions, as well as more practical issues like safety and toxicity, and establishing proper doses for administration. As an example of these active colonizers, we describe the case of Streptococcus dentisani, a new streptococcal species isolated from dental plaque of caries-free individuals. We have detected it in 98% of dental plaque samples from healthy individuals and, as expected, it does not produce any toxic secondary metabolite and does not survive a simulated stomach digestion, preventing potential secondary effects. Besides, this species has a double probiotic action, as it inhibits the growth of major oral pathogens through the production of bacteriocins, and also buffers acidic pH (the primary cause of dental caries) through an arginolytic pathway. We propose the use of S. dentisani as a promising probiotic against tooth decay.

In Vitro Effects of Polyphosphate against Prevotella intermedia in Planktonic Phase and Biofilm.

Polyphosphate (polyP) has gained a wide interest in the food industry due to its potential as a decontaminating agent. In this study, we examined the effect of sodium tripolyphosphate (polyP3; Na5P3O10) against planktonic and biofilm cells of Prevotella intermedia, a major oral pathogen. The MIC of polyP3 against P. intermedia ATCC 49046 determined by agar dilution method was 0.075%, while 0.05% polyP3 was bactericidal against P. intermedia in time-kill analysis performed using liquid medium. A crystal violet binding assay for the assessment of biofilm formation by P. intermedia showed that sub-MICs of polyP3 significantly decreased biofilm formation. Under the scanning electron microscope, decreased numbers of P. intermedia cells forming the biofilms were observed when the bacterial cells were incubated with 0.025% or higher concentrations of polyP3. Assessment of biofilm viability with LIVE/DEAD staining and viable cell count methods showed that 0.05% or higher concentrations of polyP3 significantly decreased the viability of the preformed biofilms in a concentration-dependent manner. The zone sizes of alpha-hemolysis formed on horse blood agar produced by P. intermedia were decreased in the presence of polyP3. The expression of the genes encoding hemolysins and the genes of the hemin uptake (hmu) locus was downregulated by polyP3. Collectively, our results show that polyP is an effective antimicrobial agent against P. intermedia in biofilms as well as planktonic phase, interfering with the process of hemin acquisition by the bacterium.

Repeated exposures to blue light-activated eosin Y enhance inactivation of E. faecalis biofilms, in vitro

BackgroundIn dentistry, antibacterial photodynamic therapy (a-PDT) has shown promising results for inactivating bacterial biofilms causing carious, endodontic and periodontal diseases. In the current study, we assessed the ability of eosin Y exposed to 3 irradiation protocols at inactivating Enterococcus faecalis biofilms, in vitro. MethodsE. faecalis biofilms formed on hydroxyapatite disks were incubated with eosin Y (10–80μM), then activated with blue light using different irradiation protocols. Biofilms exposed to continuous exposure were incubated for 40min before being light-activated for 960 s. For the intermittent exposure, biofilms were exposed 4 times to the light/photosensitizer combination (960 s total) without renewing the photosensitizer. For repeated a-PDT, the same light dose was delivered in a series of 4 irradiation periods separated by dark periods; fresh photosensitizer was added between each light irradiation. After treatment, bacteria were immediately labeled with LIVE/DEAD BacLight Bacterial Viability kit and viability was assessed by flow cytometry (FCM). Results were statistically analyzed using one-way ANOVA and Tukey multiple comparison intervals (α=0.05). ResultsThe viability of E. faecalis biofilms exposed to 10μM eosin Y, was significantly reduced compared to controls (light only-eosin Y only). After a second exposure to blue light-activated eosin Y, viability significantly decreased from 58% to 12% whereas 6.5% of the bacterial biofilm remained live after a third exposure (p<0.05). Only 3.5% of the bacterial population survived after the fourth exposure. ConclusionsThe results of this study indicate that blue light-activated eosin Y can photoinactivate E. faecalis biofilms grown on hydroxyapatite disks. Also, repeated exposures to blue light-activated eosin Y were shown to significantly improve efficacy. Further studies seem warranted to optimize the antibacterial activity of blue light-activated eosin Y on major oral pathogens.

In vitro effects of N-acetyl cysteine alone and in combination with antibiotics on Prevotella intermedia.

N-acetyl cysteine (NAC) is an antioxidant that possesses anti-inflammatory activities in tissues. In the field of dentistry, NAC was demonstrated to prevent the expression of LPS-induced inflammatory mediators in phagocytic cells and gingival fibroblasts during the inflammatory process, but the effect of NAC on oral pathogens has been rarely studied. Here, we examined the effect of NAC against planktonic and biofilm cells of Prevotella intermedia, a major oral pathogen. NAC showed antibacterial activity against the planktonic P. intermedia with MIC value of 3 mg/ml and significantly decreased biofilm formation by the bacterium even at sub MIC. NAC did not affect the antibiotic susceptibility of planktonic P. intermedia, showing indifference (fractional inhibitory concentration index of 0.5-4) results against the bacterium in combination with ampicillin, ciprofloxacin, tetracycline or metronidazole. On the other hand, viability of the pre-established bacterial biofilm exposed to the antibiotics except metronidazole was increased in the presence of NAC. Collectively, NAC may be used for prevention of the biofilm formation by P. intermedia rather than eradication of the pre-established bacterial biofilm. Further studies are required to explore antibacterial and anti-biofilm activity of NAC against mixed population of oral bacteria and its modulatory effect on antibiotics used for oral infectious diseases.

Blue native-PAGE analysis of membrane protein complexes in Porphyromonas gingivalis.

Porphyromonas gingivalis is a major oral pathogen associated with chronic periodontitis in humans. Secreted gingipains are considered major virulence factors of this pathogen and are secreted by a newly described type IX secretion system. This work has used 2D-BN-PAGE and MS to demonstrate that mature gingipains can independently form complexes and that substrate intermediates and mature secreted proteins of the type IX secretion system form multi-subunit complexes. Based on this work we propose that the substrates of this secretion system are secreted as large multi-subunit protein complexes. Two known important components of the secretion machinery, PG0026 and the integral outer membrane protein, LptO, were found to interact which would anchor PG0026 to the outer membrane and perhaps aid in the function of PG0026 to cleave the CTD from secreted substrates. The work has also identified more than 100 membrane proteins forming multi-subunit complexes.

Synthesis and Biological Activities of 2,6-Dihydroxy-4-Isopentenyloxychalcone as an Antimicrobial and Anti-Inflammatory Compound

Chalcones are a group of plant-derived polyphenolic compounds possessing a wide variety of biological activities. The aim of this study was to synthesize 2,6-dihydroxy-4-isopentenyloxychalcone (1), a chalcone found in plants belonging to the genera Helichrysum, Pleiotaxix and Metalasia, and evaluate its antimicrobial effects against major oral pathogens as well as its anti-inflammatory properties. Compound 1 was synthesized using a simple two-step procedure. Among the seven pathogens tested, Porphyromonas gingivalis and Prevotella intermedia were the most susceptible to inhibition by 1. This chalcone also attenuated the secretion of interleukin-8 and chemokine (C-C motif) ligand 5 (CCL5) by lipopolysaccharide (LPS)-stimulated oral epithelial cells as well as the secretion of matrix metalloproteinase 2 (MMP-2) by LPS-stimulated gingival fibroblasts. In conclusion, our study showed that 1 exerts a dual effect by acting on both oral pathogens and the host inflammatory response and thus represents a molecule of interest for periodontal infections.