Inhibitory effects of Oenothera biennis (evening primrose) seed extract on Streptococcus mutans and S. mutans-induced dental caries in rats

Peptide recovery from chicken feather keratin and their anti-biofilm properties against methicillin-resistant Staphylococcus aureus (MRSA)

Bacteria have the potential to adhere to abiotic surfaces, which has an undesirable effect in the food industry because they can survive for sustained periods through biofilm formation. In this study, an antibacterial peptide (ABP), with a molecular mass of 3861 Da, was purified from hydrolyzed chicken feathers using a locally isolated keratinolytic bacterium, namely Rhodococcus erythropolis, and its antibacterial and antibiofilm potential were investigated against planktonic and biofilm cells of Methicillin-Resistant Staphylococcus Aureus (MRSA). The results demonstrated that purified ABP showed the growth inhibition of MRSA cells with the minimum inhibitory concentration (MIC) of 45 µg/ml and disrupted MRSA biofilm formation at a concentration of 200 ug/ml, which results were confirmed by scanning electron micrograph (SEM). Moreover, the secondary structures of the peptide were assessed as part of the FTIR analysis to evaluate its mode of action. ExPASy tools were used to predict the ABP sequence, EPCVQUQDSRVVIQPSPVVVVTLPGPILSSFPQNTA, from a chicken feather keratin sequence database following in silico digestion by trypsin. Also, ABP had 54.29% hydrophobic amino acids, potentially contributing to its antimicrobial activity. The findings of toxicity prediction of the peptide by the ToxinPred tool revealed that ABP had non-toxic effects. Thus, these results support the potential of this peptide to be used as an antimicrobial agent for the treatment or prevention of MRSA biofilm formation in feed, food, or pharmaceutical applications.

The potential and outgoing trends in traditional, phytochemical, economical, and ethnopharmacological importance of family Onagraceae: A comprehensive review

ETHNOPHARMACOLOGICAL RELEVANCE

The Onagraceae is a widely distributed family of flowering plants comprises about 17 genera and more than 650 species of herbs, shrubs, and trees. Onagraceae also common as willowherb family or evening primrose family is divided into two subfamilies; Ludwigioideae (mainly genus; Ludwigia) and Onagroideae. Family Onagraceae is characterized by its numerous traditional uses as treatment of hormonal imbalances, urinary system ailments, prostate health maintenance, and antimicrobial effects.

AIM OF THE STUDY

This review aims to introduce a holistic overview on the phytochemical composition, economical importance and ethnopharmacological value of different species of family Onagraceae.

MATERIALS AND METHODS

Literature review was performed using different data bases such as PubMed, Web of Science, Google Scholar and Reaxys searching for articles focused on phytochemical composition, bioactivity and ethnopharmacological history of Onagraceae species.

RESULTS

Different species of Onagraceae were reported to have a great variety of phytochemicals including flavonoids, tannins, phenolic acids, triterpenoids, saponins, and volatile/fixed oils. Onagraceae exhibited several health benefits and pharmacological activities including anti-inflammatory, antiarthritic and analgesic, antioxidant, cytotoxic, antidiabetic, and antimicrobial.

CONCLUSIONS

Family Onagraceae is an extremely important family with diverse phytochemical composition which enriches their pharmacological importance and hence it's commercial and economical value.

Streptococcus mutans induces IgA nephropathy-like glomerulonephritis in rats with severe dental caries

The mechanisms underlying immunoglobulin A nephropathy (IgAN), the most common chronic form of primary glomerulonephritis, remain poorly understood. Streptococcus mutans, a Gram-positive facultatively anaerobic oral bacterium, is a common cause of dental caries. In previous studies, S. mutans isolates that express Cnm protein on their cell surface were frequently detected in IgAN patients. In the present study, inoculation of Cnm-positive S. mutans in the oral cavities of 2-week-old specific-pathogen free Sprague-Dawley rats fed a high-sucrose diet for 32 weeks produced severe dental caries in all rats. Immunohistochemical analyses of the kidneys using IgA- and complement C3-specific antibodies revealed positive staining in the mesangial region. Scanning electron microscopy revealed a wide distribution of electron dense deposits in the mesangial region and periodic acid-Schiff staining demonstrated prominent proliferation of mesangial cells and mesangial matrix. These results suggest that IgAN-like glomerulonephritis was induced in rats with severe dental caries by Cnm-positive S. mutans.

Effect of the Oral Administration of Common Evening Primrose Sprout (Oenothera biennis L.) Extract on Skin Function Improvement in UVB-irradiated Hairless Mice

Most of the studies on common evening primrose (Oenothera biennis L.) are focused on its oils (isolated from seed, root, and stem tissues). We aimed to investigate the effect of the oral administration of OBS-E on the improvement of skin function in skin-damaged hairless mice exposed to excessive ultraviolet B (UVB) radiation owing to the preliminary in vitro findings regarding the antioxidant, anti-wrinkle, and skin moisturizing activities of OBS-E. OBS-E administration for 14 weeks did not significantly affect the body weight or clinical signs. Significant reductions were observed in wrinkle parameters (area, number, length, and depth, and metalloproteinase levels) in OBS-E-administered mice compared with those in UVB-irradiated control mice. OBS-E significantly increased skin elasticity and hyaluronic acid content, but it significantly decreased transepidermal water loss. Histomorphometrical analysis revealed that OBS-E significantly reduced the epidermal thickness, area of the collagen-occupied region, and number of microfolds and inflammatory and mast cells. These results demonstrate that OBS-E can effectively enhance skin functions in terms of ameliorating wrinkle formation, promoting skin-moisturization, enhancing skin barrier function, and inhibiting inflammatory reactions. The obtained results provide good starting point for the continuation in the process of developing new inner beauty products based on OBS-E.

Antioxidant, Antimicrobial and Antiviral Properties of Herbal Materials

Recently, increasing public concern about hygiene has been driving many studies to investigate antimicrobial and antiviral agents. However, the use of any antimicrobial agents must be limited due to their possible toxic or harmful effects. In recent years, due to previous antibiotics' lesser side effects, the use of herbal materials instead of synthetic or chemical drugs is increasing. Herbal materials are found in medicines. Herbs can be used in the form of plant extracts or as their active components. Furthermore, most of the world's populations used herbal materials due to their strong antimicrobial properties and primary healthcare benefits. For example, herbs are an excellent material to replace nanosilver as an antibiotic and antiviral agent. The use of nanosilver involves an ROS-mediated mechanism that might lead to oxidative stress-related cancer, cytotoxicity, and heart diseases. Oxidative stress further leads to increased ROS production and also delays the cellular processes involved in wound healing. Therefore, existing antibiotic drugs can be replaced with biomaterials such as herbal medicine with high antimicrobial, antiviral, and antioxidant activity. This review paper highlights the antibacterial, antiviral, and radical scavenger (antioxidant) properties of herbal materials. Antimicrobial activity, radical scavenger ability, the potential for antimicrobial, antiviral, and anticancer agents, and efficacy in eliminating bacteria and viruses and scavenging free radicals in herbal materials are discussed in this review. The presented herbal antimicrobial agents in this review include clove, portulaca, tribulus, eryngium, cinnamon, turmeric, ginger, thyme, pennyroyal, mint, fennel, chamomile, burdock, eucalyptus, primrose, lemon balm, mallow, and garlic, which are all summarized.

Effect of apigenin on surface-associated characteristics and adherence of Streptococcus mutans

Apigenin is a type of flavonols that exhibits anti-caries properties. Bacterial adherence is the initial step in the forming of a stable biofilm that leads to caries. Bacterial adherence is affected by surface characteristics, including hydrophobicity and bacterial aggregation. However, the effect of apigenin on surface characteristics of cariogenic bacteria has not been reported. We aimed to examine the effects of apigenin on adherence and biofilm formation of Streptococcus mutans UA159. Hydrophobicity and bacterial aggregation, pac and gbpC gene expressions, and cytotoxicity on human dental pulp cells were also determined. Apigenin significantly inhibited the adherence and biofilm formation of S. mutans. Hydrophobicity decreased, whereas the aggregation rate was significantly increased compared with the control. Apigenin significantly suppressed pac and gbpC gene expressions. Apigenin exhibited acceptable biocompatibility on hDPCs. Thus, apigeinin may affect adherence and biofilm formation by altering the surface properties of S. mutans without obvious adverse effect on hDPCs.

Contribution of Streptococcus mutans to Helicobacter pylori colonisation in oral cavity and gastric tissue

Helicobacter pylori is presumed to infect gastric tissue via the oral cavity in childhood, whereas risk factors for H. pylori infection in the oral cavity are unknown. In this study, we analysed the effects of Streptococcus mutans, a major cariogenic bacterial species, on H. pylori colonisation in the oral cavity, as well as gastric tissue. Rats in the weaning period were infected with S. mutans in the oral cavity, then fed a caries-inducing diet to facilitate S. mutans colonisation. One month after S. mutans infection, rats were infected with H. pylori in the oral cavity; rats were then euthanised at 1 month after H. pylori infection. H. pylori was detected in the oral cavities of rats infected with both S. mutans and H. pylori, but not in rats infected with H. pylori alone. In addition, H. pylori colonisation in the gastric tissue and typical gastrointestinal damage were observed in rats infected with both S. mutans and H. pylori. When H. pylori was co-cultured with in vitro biofilm formed by S. mutans, a large number of H. pylori bacteria invaded the biofilm formed by S. mutans. Our results suggest that S. mutans is involved in the establishment of H. pylori infection.

Polyphenols in Dental Applications

(1) Background: polyphenols are a broad class of molecules extracted from plants and have a large repertoire of biological activities. Biomimetic inspiration from the effects of tea or red wine on the surface of cups or glass lead to the emergence of versatile surface chemistry with polyphenols. Owing to their hydrogen bonding abilities, coordination chemistry with metallic cations and redox properties, polyphenols are able to interact, covalently or not, with a large repertoire of chemical moieties, and can hence be used to modify the surface chemistry of almost all classes of materials. (2) Methods: the use of polyphenols to modify the surface properties of dental materials, mostly enamel and dentin, to afford them with better adhesion to resins and improved biological properties, such as antimicrobial activity, started more than 20 years ago, but no general overview has been written to our knowledge. (3) Results: the present review is aimed to show that molecules from all the major classes of polyphenolics allow for low coast improvements of dental materials and engineering of dental tissues.

Contribution of Severe Dental Caries Induced by Streptococcus mutans to the Pathogenicity of Infective Endocarditis

Streptococcus mutans, a major pathogen of dental caries, is regarded as a causative agent of infective endocarditis (IE), which mainly occurs in patients with underlying heart disease. However, it remains unknown whether severe dental caries that extend to pulp space represent a possible route of infection. In the present study, we evaluated the virulence of S. mutans for IE development using rats with concurrent severe dental caries and heart valve injury. Dental caries was induced in rats through the combination of a caries-inducing diet and the administration of S. mutans into the oral cavity. Then, the heart valves of a subset of rats were injured using a sterile catheter and wire under general anesthesia. The rats were euthanized at various times with various stages of dental caries. The number of teeth affected by dental caries with pulp exposure was increased in the rats in a time-dependent manner. S. mutans was recovered from injured heart tissue, which was mainly observed in rats with higher number of S. mutans bacteria in mandibular bone and a larger number of teeth in which caries extended to pulp. Dental caries was more severe in rats with heart injury than in rats without heart injury. Sequencing analysis targeting 16S rRNA revealed that specific oral bacteria appeared only in rats with heart injury, which may be related to the development of dental caries. Our findings suggest that dental caries caused by the combination of S. mutans infection and sucrose intake may contribute to S. mutans colonization in injured heart tissue.

Phytochemical and Biological Screening of Oenothera Biennis L. Hydroalcoholic Extract

Oenothera biennis L. (OB), also commonly known as evening primrose, belongs to the Onagraceae family and has the best studied biological activity of all the members in the family. In therapy, the most frequently used type of extracts are from the aerial part, which are the fatty oils obtained from the seeds and have a wide range of medicinal properties. The aim of this study was to evaluate the phytochemical composition and biological activity of OB hydroalcoholic extract and to provide directions for the antimicrobial effect, antiproliferative and pro-apoptotic potential against A375 melanoma cell line, and anti-angiogenic and anti-inflammatory capacity. The main polyphenols and flavonoids identified were gallic acid, caffeic acid, epicatechin, coumaric acid, ferulic acid, rutin and rosmarinic acid. The total phenolic content was 631.496 µgGAE/mL of extract and the antioxidant activity was 7258.67 μmolTrolox/g of extract. The tested extract had a mild bacteriostatic effect on the tested bacterial strains. It was bactericidal only against Candida spp. and S. aureus. In the set of experimental conditions, the OB extract only manifested significant antiproliferative and pro-apoptotic activity against the A375 human melanoma cell line at the highest tested concentration, namely 60 μg/mL. The migration potential of A375 cells was hampered by the OB extract in a concentration-dependent manner. Furthermore, at the highest tested concentration, the OB extract altered the mitochondrial function in vitro, while reducing the angiogenic reaction, hindering compact tumor formation in the chorioallantoic membrane assay. Moreover, the OB extract elicited an anti-inflammatory effect on the experimental animal model of ear inflammation.

Antimicrobial Activity of Cinnamaldehyde on Streptococcus mutans Biofilms

Streptococcus mutans is considered the most relevant bacteria in the transition of non-pathogenic commensal oral microbiota to biofilms which contribute to the dental caries process. The present study aimed to evaluate the antimicrobial activity of a natural plant product, cinnamaldehyde against S. mutans biofilms. Minimum inhibitory concentrations (MIC), minimal bactericidal concentration (MBC), and growth curves were determined to assess its antimicrobial effect against planktonic S. mutans. The biofilm biomass and metabolism with different concentrations of cinnamaldehyde and different incubation time points were assessed using the crystal violet and MTT assays. The biofilms were visualized using confocal laser scanning microscopy (CLSM). Bacterial cell surface hydrophobicity, aggregation, acid production, and acid tolerance were evaluated after cinnamaldehyde treatment. The gene expression of virulence-related factors (gtfB, gtfC, gtfD, gbpB, comDE, vicR, ciaH, ldh and relA) was investigated by real-time PCR. The MIC and MBC of cinnamaldehyde against planktonic S. mutans were 1000 and 2000 μg/mL, respectively. The results showed that cinnamaldehyde can decrease biofilm biomass and metabolism at sub-MIC concentrations. CLSM images revealed that the biofilm-covered surface areas decreased with increasing concentrations of cinnamaldehyde. Cinnamaldehyde increased cell surface hydrophobicity, reduced S. mutans aggregation, inhibited acid production, and acid tolerance. Genes expressions in the biofilms were down-regulated in the presence of cinnamaldehyde. Therefore, our data demonstrated that cinnamaldehyde at sub-MIC level suppressed the microbial activity on S. mutans biofilm by modulating hydrophobicity, aggregation, acid production, acid tolerance, and virulence gene expression.

Binding forces of Streptococcus mutans P1 adhesin

Streptococcus mutans is a Gram-positive oral bacterium that is a primary etiological agent associated with human dental caries. In the oral cavity, S. mutans adheres to immobilized salivary agglutinin (SAG) contained within the salivary pellicle on the tooth surface. Binding to SAG is mediated by cell surface P1, a multifunctional adhesin that is also capable of interacting with extracellular matrix proteins. This may be of particular importance outside of the oral cavity as S. mutans has been associated with infective endocarditis and detected in atherosclerotic plaque. Despite the biomedical importance of P1, its binding mechanisms are not completely understood. In this work, we use atomic force microscopy-based single-molecule and single-cell force spectroscopy to quantify the nanoscale forces driving P1-mediated adhesion. Single-molecule experiments show that full-length P1, as well as fragments containing only the P1 globular head or C-terminal region, binds to SAG with relatively weak forces (∼50 pN). In contrast, single-cell analyses reveal that adhesion of a single S. mutans cell to SAG is mediated by strong (∼500 pN) and long-range (up to 6000 nm) forces. This is likely due to the binding of multiple P1 adhesins to self-associated gp340 glycoproteins. Such a cooperative, long-range character of the S. mutans-SAG interaction would therefore dramatically increase the strength and duration of cell adhesion. We also demonstrate, at single-molecule and single-cell levels, the interaction of P1 with fibronectin and collagen, as well as with hydrophobic, but not hydrophilic, substrates. The binding mechanism (strong forces, cooperativity, broad specificity) of P1 provides a molecular basis for its multifunctional adhesion properties. Our methodology represents a valuable approach to probe the binding forces of bacterial adhesins and offers a tractable methodology to assess anti-adhesion therapy.

Identification and functional analysis of an ammonium transporter in Streptococcus mutans

Streptococcus mutans, a Gram-positive bacterium, is considered to be a major etiologic agent of human dental caries and reported to form biofilms known as dental plaque on tooth surfaces. This organism is also known to possess a large number of transport proteins in the cell membrane for export and import of molecules. Nitrogen is an essential nutrient for Gram-positive bacteria, though alternative sources such as ammonium can also be utilized. In order to obtain nitrogen for macromolecular synthesis, nitrogen-containing compounds must be transported into the cell. However, the ammonium transporter in S. mutans remains to be characterized. The present study focused on characterizing the ammonium transporter gene of S. mutans and its operon, while related regulatory genes were also analyzed. The SMU.1658 gene corresponding to nrgA in S. mutans is homologous to the ammonium transporter gene in Bacillus subtilis and SMU.1657, located upstream of the nrgA gene and predicted to be glnB, is a member of the PII protein family. Using a nrgA-deficient mutant strain (NRGD), we examined bacterial growth in the presence of ammonium, calcium chloride, and manganese sulfate. Fluorescent efflux assays were also performed to reveal export molecules associated with the ammonium transporter. The growth rate of NRGD was lower, while its fluorescent intensity was much higher as compared to the parental strain. In addition, confocal laser scanning microscopy revealed that the structure of biofilms formed by NRGD was drastically different than that of the parental strain. Furthermore, transcriptional analysis showed that the nrgA gene was co-transcribed with the glnB gene. These results suggest that the nrgA gene in S. mutans is essential for export of molecules and biofilm formation.