Inhibitory effects of β-caryophyllene on Streptococcus mutans biofilm

Exploring the Therapeutic Potential of Terpenoids for Depression and Anxiety

This review focus on the terpenoids as potential therapeutic agents for depression and anxiety disorders, which naturally found in a variety of plants and exhibit a wide range of biological activities. Among the terpenoids discussed in this review are α-pinene, β-caryophyllene, α-phellandrene, limonene, β-linalool, 1, 8-cineole, β-pinene, caryophyllene oxide, p-cymene, and eugenol. All of these compounds have been studied extensively regarding their pharmacological properties, such as neuroprotective effect, anti-inflammation, antibacterial, regulation of neurotransmitters and antioxidant effect. Preclinical evidence are reviewed to highlight their diverse mechanisms of action and therapeutic potential to support antidepressant and anxiolytic properties. Additionally, challenges and future directions are also discussed to emphasize therapeutic utility of terpenoids for mental health disorders. Overall, this review provides a promising role of terpenoids as novel therapeutic agents for depression and anxiety, with potential implications for the development of more effective and well-tolerated treatments in the field of psychopharmacology.

Hoslundia opposita vahl; a potential source of bioactive compounds with antioxidant and antibiofilm activity for wound healing

BACKGROUND

Biofilms and oxidative stress retard wound healing. The resistance of biofilms to antibiotics has led to a search for alternative approaches in biofilm elimination. Antioxidants work synergistically with antibacterial agents against biofilms. Hence recent research has suggested plants as candidates in the development of new alternatives in biofilm treatments and as antioxidants due to the presence of phytocompounds which are responsible for their bioactivities. Hoslundia opposita Vahl is one of the plants used by traditional healers to treat wounds and other infections, this makes it a potential candidate for drug discovery hence, in this study, we investigate the antibiofilm and antioxidant activity of methanolic extract of hoslundia opposita Vahl from Uganda. We also identify phytochemicals responsible for its bioactivity.

METHOD

the plant was extracted by maceration using methanol, and the extract was investigated for antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) assay. The antibiofilm activity using microtiter plate assay (MTP) assay where the Minimum biofilm inhibitory concentration required to inhibit 50% or 90% of the biofilm (MBIC50 and MBIC90) and Minimum biofilm eradication concentration required to remove 50% or 90% of the biofilm (MBEC50 and MBEC90) were measured. It was further analysed for its phytochemical composition using quantitative screening, as well as Gas chromatography-mass spectrometry (GC-MS) and Liquid chromatography mass-spectrometry (LC-MS).

RESULTS

H. Opposita Vahl extract showed good antioxidant activity with of 249.6 mg/mL. It inhibited the growth of P. aeruginosa and S. aureus biofilms with MBIC50 of 28.37 mg/mL and 10 mg/mL, respectively. It showed the ability to eradicate P. aeruginosa and S. aureus biofilms with MBEC50 of 23.85 and 39.01 mg/mL respectively. Phytochemical analysis revealed the presence of alkaloids, tannins, flavonoids, and phenols. GC-MS analysis revealed 122 compounds in the extract of which, 23 have evidence of antioxidant or antibiofilm activity in literature. The most abundant compounds were; 1,4- Citric acid, Tetracontane-1,40-diol (43.43.3%, 1, Olean-12-en-28-oic acid, 3-hydroxy-, methyl ester, (3.beta) (15.36%) 9-Octadecenamide (12.50%), Squalene (11.85%) Palmitic Acid 4TMS (11.28%), and alpha Amyrin (11.27%). The LC-MS identified 115 and 57 compounds in multiple reaction mode (MRM) and scan modes respectively.

CONCLUSION

H. opposita Vahl showed antibiofilm and antioxidant activity due to bioactive compounds identified, hence the study justifies its use for wound healing. It can be utilised in further development of new drugs as antibiofilm and antioxidants.

Biological Properties of Mentha viridis L. Essential Oil and Its Main Monoterpene Constituents

This research aimed to evaluate the antidiabetic, dermatoprotective, and antibacterial activities of Mentha viridis L. essential oil (MVEO) collected in the province of Ouezzane (Northwest Morocco). Gas chromatography-mass spectrometry (GC-MS) analysis revealed that the main constituents of MVEO were carvone (37.26 %), 1,8-cineole (11.82 %), limonene (5.27 %), α-terpineol (4.16 %), and β-caryophyllene (4.04 %). MVEO showed strong inhibitory effects on α-amylase and α-glucosidase activities, exceeding those of acarbose, but weak anti-elastase activity. The main compounds, β-caryophyllene (IC50=79.91±2.24 and 62.08±2.78 μg/mL) and limonene (IC50=90.73±3.47 and 68.98±1, 60 μg/mL), demonstrated the strongest inhibitory effects on both digestive enzymes (α-glucosidase and α-amylase, respectively). In silico investigations, using molecular docking, also showed the inhibitory potential of these bioactive compounds against the enzymes tested. In conclusion, MVEO, due to its main components such as limonene, 1,8-cineole, β-caryophyllene, carvone, and α-terpineol, shows promising prospects for drug discovery and natural therapeutic applications.

Comparison of the Effects of Essential Oils from Cannabis sativa and Cannabis indica on Selected Bacteria, Rumen Fermentation, and Methane Production-In Vitro Study

This study aimed to evaluate the effects of essential oils (EOs) extracted from Cannabis sativa L. and Cannabis indica Lam. on in vitro ruminal fermentation characteristics, selected rumen microbial populations, and methane production. GC-MS analyses allowed us to identify 89 compounds in both EOs. It was found that E-β-caryophyllene predominated in C. sativa (18.4%) and C. indica (24.1%). An in vitro (Ankom) test was performed to analyse the control and monensin groups, as well as the 50 µL or 100 µL EOs. The samples for volatile fatty acids (VFAs), lactate, and microbiological analysis were taken before incubation and after 6 and 24 h. The application of EOs of C. indica resulted in an increase in the total VFAs of acetate and propionate after 6 h of incubation. The applied EOs had a greater impact on the reduction in methane production after 6 h, but no apparent effect was noted after 24 h. Lower concentrations of C. sativa and C. indica had a more pronounced effect on Lactobacillus spp. and Buryrivibrio spp. than monensin. The presented findings suggest that C. sativa and C. indica supplementation can modify ruminal fermentation, the concentrations of specific volatile fatty acids, and methane production.

Evaluation of Yield, Chemical Profile, and Antimicrobial Activity of Teucrium polium L. Essential Oil Used in Iranian Folk Medicine

Teucrium polium L. is used to treat many diseases like abdominal pains, indigestion, colds, and reproductive system diseases in Iranian folk medicine. This study was designed to investigate the yield, chemical profile of essential oil, and antibacterial and antifungal activity of this species. The flowering aerial parts of T. polium were collected from the Margh region of Kashan, Iran. The essential oil of the plant was extracted and separated using the Clevenger apparatus and analyzed using gas chromatography-mass spectrometry (GC-MS). The antimicrobial activity of the essential oil against a variety of standard microbial strains was investigated with the Agar well-diffusion method and determination of the lowest growth inhibitory and lethal concentration (MIC and MBC). The results showed that the yield of T. polium essential oil (TPEO) was 0.5778%. Based on the results of GC-MS, 76 compounds (99.3%) were identified in the TPEO, of which α-pinene (9.67%), β-caryophyllene (8.07%), β-pinene (5.04%), nerolidol (4.94%), and oleic acid (4.57%) were the dominant components. The results of antimicrobial tests showed that the TPEO on Staphylococcus aureus created the largest zone of inhibition (~ 14.29 mm). The dominant inhibitory activity of this essential oil was against Gram-negative bacteria Escherichia coli (~ 9.00 mm), which was almost similar to rifampin (~ 11 mm). It seems that the predominance of terpenoid and acidic compounds of the essential oil is one of the possible factors of the anti-bacterial activity of this essential oil. Therefore, the TPEO may be a promising and potential strategy to inhibit some bacterial strains.

Volatile Composition, Antimicrobial Activity, and In Vitro Innate Immunomodulatory Activity of Echinacea purpurea (L.) Moench Essential Oils

Echinacea purpurea (L.) Moench is a medicinal plant commonly used for the treatment of upper respiratory tract infections, the common cold, sore throat, migraine, colic, stomach cramps, and toothaches and the promotion of wound healing. Based on the known pharmacological properties of essential oils (EOs), we hypothesized that E. purpurea EOs may contribute to these medicinal properties. In this work, EOs from the flowers of E. purpurea were steam-distilled and analyzed by gas chromatography-mass spectrometry (GC-MS), GC with flame-ionization detection (GC-FID), and chiral GC-MS. The EOs were also evaluated for in vitro antimicrobial and innate immunomodulatory activity. About 87 compounds were identified in five samples of the steam-distilled E. purpurea EO. The major components of the E. purpurea EO were germacrene D (42.0 ± 4.61%), α-phellandrene (10.09 ± 1.59%), β-caryophyllene (5.75 ± 1.72%), γ-curcumene (5.03 ± 1.96%), α-pinene (4.44 ± 1.78%), δ-cadinene (3.31 ± 0.61%), and β-pinene (2.43 ± 0.98%). Eleven chiral compounds were identified in the E. purpurea EO, including α-pinene, sabinene, β-pinene, α-phellandrene, limonene, β-phellandrene, α-copaene, β-elemene, β-caryophyllene, germacrene D, and δ-cadinene. Analysis of E. purpurea EO antimicrobial activity showed that they inhibited the growth of several bacterial species, although the EO did not seem to be effective for Staphylococcus aureus. The E. purpurea EO and its major components induced intracellular calcium mobilization in human neutrophils. Additionally, pretreatment of human neutrophils with the E. purpurea EO or (+)-δ-cadinene suppressed agonist-induced neutrophil calcium mobilization and chemotaxis. Moreover, pharmacophore mapping studies predicted two potential MAPK targets for (+)-δ-cadinene. Our results are consistent with previous reports on the innate immunomodulatory activities of β-caryophyllene, α-phellandrene, and germacrene D. Thus, this study identified δ-cadinene as a novel neutrophil agonist and suggests that δ-cadinene may contribute to the reported immunomodulatory activity of E. purpurea.

Phytochemical analysis and antibacterial/antifungal activity of the essential oil of Phlomis olivieri Benth in Iran

Phlomis olivieri Benth. is an aromatic plant endemic to Iran belonging to the Lamiaceae family. It is used to treat pain, stomach ache and common cold in Iranian traditional medicine. P. olivieri also has valuable biological properties including antioxidant, antimicrobial and analgesic ones. This was the first study designed to assess the quality, quantity and antimicrobial activity of Phlomis olivieri Benth. essential oil (POEO). Samples were randomly collected from flowering twigs of this species in three locations between Azeran and Kamoo in Kashan, Iran at peak flowering in June 2019. Water distillation extraction was used to obtain the POEO the quantity of which was calculated by weight. Gas chromatography coupled to mass spectrometry (GC/MS) was also used for POEO qualitative analysis, which revealed its chemical compounds and their percentages. Antimicrobial activity of POEO was also determined using the agar well diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) were also measured using the broth microdilution method. The results of the quantitative and qualitative analysis showed that the POEO yield was ~ 0.2292% and its main chemical compounds included the sesquiterpenes germacrene D (26.43%), β-caryophyllene (20.72%), elixene (6.58%), β-trans-farnesene (6.17%), β-Cyclogermacrane (5.04%), germacrene B (4.73%), α-humulene (4.22%), and monoterpene α-pinene (3.22%). The agar diffusion method demonstrated the highest antimicrobial activity of POEO (MIC ~ 14.50 mm) was against the Gram-positive species Streptococcus pyogenes. The POEO also showed the strongest inhibitory and lethal activity against the gram-negative bacterial species Pseudomonas aeruginosa (MIC < 62.50 μg/mL) and S. paratyphi-A (MIC < 62.50 μg/mL and MBC = 125 μg/mL), and fungal species Candida albicans (MIC and MBC = 250 μg/mL) as compared to control-positive antibiotics. Therefore, POEO is a valuable natural alternative rich in sesquiterpenes with strong antimicrobial and antifungal activities against some fungal and bacterial strains. It can also be used in the pharmaceutical, food and cosmetic industries.

New Strategies for Biocontrol of Bacterial Toxins and Virulence: Focusing on Quorum-Sensing Interference and Biofilm Inhibition

The overuse of antibiotics and the emergence of multiple-antibiotic-resistant pathogens are becoming a serious threat to health security and the economy. Reducing antimicrobial resistance requires replacing antibiotic consumption with more biocontrol strategies to improve the immunity of animals and humans. Probiotics and medicinal plants have been used as alternative treatments or preventative therapies for a variety of diseases caused by bacterial infections. Therefore, we reviewed some of the anti-virulence and bacterial toxin-inhibiting strategies that are currently being developed; this review covers strategies focused on quenching pathogen quorum sensing (QS) systems, the disruption of biofilm formation and bacterial toxin neutralization. It highlights the probable mechanism of action for probiotics and medicinal plants. Although further research is needed before a definitive statement can be made on the efficacy of any of these interventions, the current literature offers new hope and a new tool in the arsenal in the fight against bacterial virulence factors and bacterial toxins.

Antibacterial mechanism of areca nut essential oils against Streptococcus mutans by targeting the biofilm and the cell membrane

Introduction

Dental caries is one of the most common and costly biofilm-dependent oral diseases in the world. Streptococcus mutans is the major cariogenic pathogen of dental caries. S. mutans synthesizes extracellular polysaccharides by autologous glucosyltransferases, which then promotes bacterial adhesion and cariogenic biofilm formation. The S. mutans biofilm is the principal target for caries treatment. This study was designed to explore the antibacterial activity and mechanisms of areca nut essential oil (ANEO) against S. mutans.

Methods

The ANEOs were separated by negative pressure hydro-distillation. The Kirby-Bauer method and broth microdilution method were carried out to evaluate the antibacterial activity of different ANEOs. The antibacterial mechanism was revealed by crystal violet staining, XTT reduction, microbial adhesion to hydrocarbon test, extracellular polysaccharide production assay, glucosyltransferase activity assay, lactate dehydrogenase leaking, propidium iodide staining and scanning electron microscopy (SEM). The cytotoxicity of ANEOs was determine by MTT assay.

Results

The ANEOs separated at different temperatures exhibited different levels of antibacterial activity against S. mutans, and the ANEO separated at 70°C showed the most prominent bacteriostatic activity. Anti-biofilm experiments showed that the ANEOs attenuated the adhesion ability of S. mutans by decreasing the surface hydrophobicity of the bacteria, prevented S. mutans biofilm formation by inhibiting glucosyltransferase activity, reducing extracellular polysaccharide synthesis, and reducing the total biofilm biomass and activity. SEM further demonstrated the destructive effects of the ANEOs on the S. mutans biofilm. Cell membrane-related experiments indicated that the ANEOs destroyed the integrity of the cell membrane, resulting in the leakage of lactic dehydrogenase and nucleic acids. SEM imaging of S. mutans cell showed the disruption of the cellular morphology by the ANEOs. The cytotoxicity assay suggested that ANEO was non-toxic towards normal oral epithelial cells.

Discussion

This study displayed that ANEOs exerted antibacterial activity against S. mutans primarily by affecting the biofilm and disrupting the integrity of the cell membrane. ANEOs has the potential to be developed as an antibacterial agent for preventing dental caries. Additionally, a new method for the separation of essential oil components is presented.

Biochemical, Antioxidant Properties and Antimicrobial Activity of Steno-Endemic Origanum onites

Origanum onites (Lamiaceae) is an Eastern Mediterranean plant that is widely used in Turkish traditional medicine. This study aimed to investigate the biochemical composition, antimicrobial activity, and antioxidant potential of O. onites. In this study, the biochemical composition of the O. onites ethanol extract (OOEt) was analyzed using GC-MS. The antimicrobial activity was investigated using a disk diffusion test and determining minimum inhibitory concentrations (MIC) against 30 microorganism strains, including 28 bacteria (some multidrug-resistant) and 2 fungi. Additionally, the antioxidant activity was evaluated using the DPPH method. The main component identified was carvacrol. OOEt demonstrated antimicrobial activity against a wide range of tested microorganism strains. OOEt displayed the highest activity against E. faecium (a Gram-positive bacterium) at 100 µL with a 52 mm inhibition zone. Additionally, P. aeruginosa DSMZ 50071 and P. fluorescens P1, which are Gram-negative bacteria, were the most sensitive strains with a 24 mm inhibition zone in 100 µL of OOEt. The data obtained from A. baumannii (a multidrug-resistant strain) is particularly striking, as higher activity was observed compared to all positive controls. All tested fungal strains showed more effective results than positive controls. The antioxidant activity of OOEt was found to be stronger than that of the positive control, ascorbic acid. This study determined that O. onites has significant antimicrobial and antioxidant potential.

Antibacterial and Analgesic Properties of Beta-Caryophyllene in a Murine Urinary Tract Infection Model

Beta-caryophyllene has demonstrated anti-inflammatory effects in a variety of conditions, including interstitial cystitis. These effects are mediated primarily via the activation of the cannabinoid type 2 receptor. Additional antibacterial properties have recently been suggested, leading to our investigation of the effects of beta-caryophyllene in a murine model of urinary tract infection (UTI). Female BALB/c mice were intravesically inoculated with uropathogenic Escherichia coli CFT073. The mice received either beta-caryophyllene, antibiotic treatment using fosfomycin, or combination therapy. After 6, 24, or 72 h, the mice were evaluated for bacterial burden in the bladder and changes in pain and behavioral responses using von Frey esthesiometry. In the 24 h model, the anti-inflammatory effects of beta-caryophyllene were also assessed using intravital microscopy. The mice established a robust UTI by 24 h. Altered behavioral responses persisted 72 h post infection. Treatment with beta-caryophyllene resulted in a significant reduction in the bacterial burden in urine and bladder tissues 24 h post UTI induction and significant improvements in behavioral responses and intravital microscopy parameters, representing reduced inflammation in the bladder. This study demonstrates the utility of beta-caryophyllene as a new adjunct therapy for the management of UTI.

Anti-Streptococcus mutans, anti-adherence and anti-acidogenic activity of Uvaria chamae P. Beauv

ETHNOPHARMACOLOGICAL RELEVANCE

Streptococcus mutans a key pathogen, produces biofilm, acids and extracellular polysaccharides in the oral cavity; which leads to the development of dental caries. Control of these pathogenic markers can prevent dental caries. Uvaria chamae P. Beauv. is a medicinal plant traditionally used for many ailments including oral infections. Root, leaves and bark extracts has proven antibacterial activity including activity against caries causing S. mutans. However, its effect on the virulence properties of S. mutans, responsible for the development of dental caries, has not been studied.

AIM OF THE STUDY

This study investigated the phytochemical constituents, anti-S. mutans, anti-adherence and anti-acidogenic activity of U. chamae root extract.

MATERIALS AND METHODS

Extracts were prepared and phytochemical analysis was performed. Minimum inhibitory concentrations (MIC) were determined, and MIC and sub-MIC concentrations of the best solvent were selected for their effect on the virulence factors of S. mutans. The results were analysed using one-way ANOVA and Wilcoxon Rank Sum Tests.

RESULTS

The dichloromethane extract, with proanthocyanidin as a major chemical constituent, produced an MIC of 0.02 mg/ml. At 6 h, exposure to 0.005, 0.01, and 0.02 mg/ml extract significantly reduced S. mutans adherence by 39, 59, and 77% respectively (p < 0.05). Uvaria chamae also significantly inhibited acid production in S. mutans at 10, 12, 14 and 16 h (p < 0.05). At ½ MIC, the plant extract caused remarkable downregulation of the virulence genes responsible for the adherence, biofilm formation, extracellular polysaccharide synthesis and acid production.

CONCLUSIONS

This suggests that U. chamae extract may potentially be used to inhibit the proliferation of S. mutans and silencing the expression of pathology-related genes, which will prevent the development of dental caries.

Composition, Antibacterial Efficacy, and Anticancer Activity of Essential Oil Extracted from Psidium guajava (L.) Leaves

Essential oils (EO) are used as a natural remedy to treat various chronic diseases, although clinical evidence is lacking. In this context, we have endeavored to measure the percentage of chemical composition and biological efficacy of Psidium guajava (guava) leaf essential oil in treating oral infections and oral cancer. The essential oil obtained from hydrodistillation of P. guajava L. leaves was analyzed by gas chromatography−mass spectrometry (GC−MS). The activities of selected oral pathogens Candida albicans (C. albicans) and Streptococcus mutans (S. mutants) were studied in vitro and in silico. MTT assay was used to test for anticancer activity against human oral epidermal carcinoma (KB). GC−MS showed that the main components of PGLEO were limonene (38.01%) and β-caryophyllene (27.98%). Minimum inhibitory concentrations (MICs) of 0.05−0.1% were demonstrated against C. albicans and S. mutans. Antimicrobial activity against C. albicans and S. mutans, as shown by molecular linkage analysis, revealed that the main metabolites, limonene and β-caryophyllene, potentially inhibited the receptors of C. albicans and S. mutans. PGLEO showed significant (p < 0.001) anticancer activity (45.89%) at 200 µg/mL compared to doxorubicin (47.87%) with an IC50 value of 188.98 µg/mL. The outcomes of the present study suggest that PGLEO has promising antimicrobial and anticancer activities and could be a useful source for developing a natural therapeutic agent for oral infections and oral cancer.

A GC-MC analysis of chemical compounds and identification of the antibacterial characteristics of the essential oil of two species exclusive to Iranian habitats: New chemotypes

BACKGROUND

The diversity found in the chemical compounds of a single species in different regions results in different biologic characteristics which can be considered as a strong source for identifying new chemotypes. Hymenocrater incanus Bunge and Dracocephalum kotschyi Boiss. are exclusive species of the Lamiaceae family which grow in the western and central habitats of Iran. This study was designed and carried out to determine the yield, identify the chemical compounds, and evaluate the antimicrobial characteristics of the essential oil (EO) of these two species in Iran for the first time.

METHODS

The flowering twigs of the species D. kotschyi and H. incanus were collected from the villages of Totmach and Kamu in Isfahan province respectively, in May 2019. The EO of these plants was extracted and separated using the water distillation method, utilizing the Clevenger device. The EO compounds were analyzed using a gas chromatograph coupled with a mass spectrometer (GC-MS). The evaluation of antimicrobial characteristics was carried out by determining the growth inhibition zone implementing the Agar method, the minimum inhibition concentration (MIC), and the minimum bactericidal/fungicidal concentration (MFC/MBC) utilizing liquid dilution culture.

RESULTS

The results indicated that the highest yield belonged to the EO of D. kotschyi at %2.6 (w/w). In this EO there were citral (%25.44), neral (%20.87), α-pinene (%14.48), trans-geranic acid methyl ester (%9.74), and D-limonene (%6.87). Moreover, H. incanus had the dominant compounds (-)-Spathulenol (%12.61), caryophyllene (%10.00), linolenic acid (%8.54), 1,8-cineole (%5.95), palmitic acid (%5.35), and α-cadinol (%5.17). The largest diameter of growth inhibition zone belonged to the H. incanus EO against the Gram-positive bacteria S. pyogenes (~17.67mm). The strongest inhibition activities in the form of growth inhibition diameter exhibited by the D. kotschyi EO were against the Gram-negative bacteria S. paratyphi-A serotype (~ 12 mm), K. pneumoniae, and Sh. dysenteriae (~ 11 mm) which was significant compared to the Gram-positive rifampin (~ 8 mm).

CONCLUSIONS

It can be seen that these species are new chemotypes with special and novel chemical compounds which can potentially be used to manufacture natural antibiotics against some bacterial strains.

Development and Physicochemical Characterization of Eugenia brejoensis Essential Oil-Doped Dental Adhesives with Antimicrobial Action towards Streptococcus mutans

Dental caries is a multifactorial, biofilm-dependent infectious disease that develops when detrimental changes occur in the oral cavity microenvironment. The antimicrobial and antivirulence properties of the essential oil obtained from the leaves of Eugenia brejoensis Mazine (EBEO) have been reported against Gram-positive and Gram-negative bacteria. Herein, the antimicrobial action of EBEO towards Streptococcus mutans is reported, along with the development and characterization of dental adhesives doped with. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of EBEO were determined against S. mutans, while its toxicity was analyze using Tenebrio molitor larvae. EBEO (MIC and 10×MIC) was incorporated into the Ambar Advanced Polymerization System® (Ambar APS), a two-step total-etch adhesive system (FGM Dental Group), and the antibiofilm action was evaluated. The reflective strength, modulus of elasticity, degree of conversion, and maximum rate of polymerization of each adhesive were also determined. The MIC and MBC values of EBEO against S. mutans were 62.5 µg/mL. The tested concentrations of EBEO were non-toxic to T. molitor larvae. The formation of S. mutans biofilms was significantly inhibited by EBEO and EBEO-coated resin discs (p < 0.05). Importantly, EBEO incorporation did not affect the mechanical and physicochemical properties in relation to oil-free adhesive version. EBEO showed strong antibacterial and antibiofilm activity against S. mutans, no toxicity effect against T. molitor larvae, and did not jeopardize the physical-chemical properties tested.

Essential oil from the leaves of Eugenia pohliana DC. (Myrtaceae) alleviate nociception and acute inflammation in mice

Eugenia pohliana DC.(Myrtaceae) is used in folk medicine by communities in Brazil. However, there are no reports on its biological activity. This is the first study to identify the components of E. pohliana essential oil (EpEO) and evaluate their antinociceptive and anti-inflammatory activities in an in vivo model at doses of 25, 50, and 100 mg/kg. The essential oil (EO) was obtained by hydrodistillation, and the analysis was performed by gas chromatography coupled with mass spectrometry. Antinociceptive activity was evaluated by writhing tests, tail movement, and formalin (neurogenic and inflammatory pain); naloxone was used to determine the nociception mechanism. Anti-inflammatory activity was assessed by oedema and peritonitis tests. We found that (E)-β-caryophyllene (BCP) (15.56%), δ-cadinene (11.24%) and α-cadinol (10.89%) were the major components. In the writhing test, there was a decrease in writing by 42.95-70.70%, in the tail movement, an increase in latency time by 69.12-86.63%, and in the formalin test, there was a reduction in pain neurogenic by 29.54-61.74%, and inflammatory pain by 37.42-64.87%. The antinociceptive effect of EpEO occurs through the activation of opioid receptors. In addition, a reduction in inflammation by 74.93‒81.41% was observed in the paw edema test and inhibition of the influx of leukocytes by 51.86‒70.38% and neutrophils by 37.74‒54.72% in the peritonitis test. It was concluded that EpEO has antinociceptive effect by the opioid pathway, as shown by the inhibitory effect of naloxone, and anti-inflammatory actions, and that its use does not cause hemolytic damage or behavioral change.

Mechanisms, Anti-Quorum-Sensing Actions, and Clinical Trials of Medicinal Plant Bioactive Compounds against Bacteria: A Comprehensive Review

Bacterial strains have developed an ability to resist antibiotics via numerous mechanisms. Recently, researchers conducted several studies to identify natural bioactive compounds, particularly secondary metabolites of medicinal plants, such as terpenoids, flavonoids, and phenolic acids, as antibacterial agents. These molecules exert several mechanisms of action at different structural, cellular, and molecular levels, which could make them candidates or lead compounds for developing natural antibiotics. Research findings revealed that these bioactive compounds can inhibit the synthesis of DNA and proteins, block oxidative respiration, increase membrane permeability, and decrease membrane integrity. Furthermore, recent investigations showed that some bacterial strains resist these different mechanisms of antibacterial agents. Researchers demonstrated that this resistance to antibiotics is linked to a microbial cell-to-cell communication system called quorum sensing (QS). Consequently, inhibition of QS or quorum quenching is a promising strategy to not only overcome the resistance problems but also to treat infections. In this respect, various bioactive molecules, including terpenoids, flavonoids, and phenolic acids, exhibit numerous anti-QS mechanisms via the inhibition of auto-inducer releases, sequestration of QS-mediated molecules, and deregulation of QS gene expression. However, clinical applications of these molecules have not been fully covered, which limits their use against infectious diseases. Accordingly, the aim of the present work was to discuss the role of the QS system in bacteria and its involvement in virulence and resistance to antibiotics. In addition, the present review summarizes the most recent and relevant literature pertaining to the anti-quorum sensing of secondary metabolites and its relationship to antibacterial activity.

Phytochemical Screening, Nutritional Value, Anti-Diabetic, Anti-Cancer, and Anti-Bacterial Assessment of Aqueous Extract from Abelmoschus esculentus Pods

Known for its high nutritional and medicinal value, okra (Abelmoschus esculentus) is commonly used for replacing plasma and expanding blood volume in humans. It is a major economic crop cultivated in tropical and subtropical regions worldwide. The present study aimed to investigate and evaluate the nutritional properties and prospective applications of the consumable parts of okra. The total ash content (mineral content), carbohydrate, crude fiber, fat, protein, and moisture fractions of okra pod aqueous extract were determined. The results show that okra aqueous extract contained 84.670–87.650% moisture, 1.514–1.197% ash, 7.857–8.261% carbohydrate, 2.367–3.410% crude protein, and 6.781–8.314% crude fiber. Okra was determined to have high nutritional value, with γ-tocopherol and α-tocopherol contents about 2.67 mg/100 g and 1.62 mg/100 g, respectively. High-performance liquid chromatography (HPLC) was performed to determine the sugars present in okra aqueous extract. The water-soluble polysaccharide content was 10.22–16.45 g/100 g. The tested aqueous extract was a rich source of total phenolic compounds in gallic acid equivalents (288.2–3426.2 mg/100 g), chlorophyll a (3.53 mg/100), chlorophyll b (2.43 mg/100), and carotenoids (1.3 mg/100 g). The detected minerals were Ca, Mg, Cu, Zn, Fe, K, Na, and Mn. Atomic absorption spectrometry analysis of these ashed minerals was performed. In addition to the nutritional benefits, okra pods exhibited antimicrobial, anticancer, and antioxidant properties. The aqueous extract was found to be potentially active against bacterial strains of Staphylococcus aureus (MIC value = 21.8 mg/mL), Escherichia coli (MIC value = 18.7 mg/mL), Bacillus cereus (MIC value = 20.7 mg/mL), and Klebsiella pneumoniae (MIC value = 20.2 mg/mL). Okra aqueous extract exhibited inhibitory activity against α-amylase (IC50 = 120 µg/mL) and α-glucosidase (IC50 = 115 µg/mL). The okra extract exhibited high anticancer activity, concentration-dependent and with an IC50 value of about 158.3 mg/mL. The results indicated that okra pods have nutritional and medicinal properties and, hence, can be used as a functional food and broad-spectrum nutraceutical supplement.

Inhibitory effect of a gel paste containing surface pre-reacted glass-ionomer (S-PRG) filler on the cariogenicity of Streptococcus mutans

Surface pre-reacted glass-ionomer (S-PRG) filler is a bioactive functional glass that releases six different ions. Although several dental materials containing S-PRG filler have been developed, few self-care products containing S-PRG filler have been reported. We investigated the inhibitory effects of PRG gel paste containing S-PRG filler on Streptococcus mutans, a major pathogen of dental caries. PRG gel paste inhibited bacterial growth of S. mutans in a concentration-dependent manner, and all S. mutans were killed in the presence of ≥ 1% PRG gel paste. Additionally, it was difficult for S. mutans to synthesize insoluble glucan from sucrose in the presence of 0.1% PRG gel paste. A biofilm formation model was prepared in which slices of bovine enamel were infected with S. mutans after treatment with or without PRG gel paste. Biofilm formation was inhibited significantly more on the enamel treated with PRG gel paste than on enamel without PRG gel paste (P < 0.001). The inhibitory effects on bacterial growth and biofilm formation were more prominent with PRG gel paste than with S-PRG-free gel paste, suggesting that PRG gel paste may be effective as a self-care product to prevent dental caries induced by S. mutans.

Exploiting the chemical composition of essential oils from Psidium cattleianum and Psidium guajava and its antimicrobial and antioxidant properties

The genus Psidium comprises several native Brazilian plants, such as the araçá and guava trees. They are interesting sources of essential oils (EOs) that can be used as natural preservatives in foods due to their bioactive properties. This work aimed to evaluate and correlate the biological properties of the EOs from araçá and guava leaves with their chemical compounds. The gas chromatography-mass spectrometry (GC/MS) was used to determine the chemical composition of EOs. The antimicrobial activity was tested against 16 foodborne pathogens and the antioxidant capacity was determined by ABTS, DPPH, and FRAP assays. The major compounds identified in the essential oil of araçá (EOA) were β-caryophyllene and β-elemene, representing 38.69% and 7.47%, respectively, whereas β-selinene (13.83%), α-humulene (10.90%), and β-caryophyllene (7.61%) were the major compounds identified in the essential oil of guava (EOG). Both EOs showed activity against Salmonella Enteritidis, with MIC being 1.41 µg/ml for the EOA and 1.37 µg/ml for the EOG. The EOA was more effective than the EOG against strains of Listeria monocytogenes and Pseudomonas aeruginosa, with the MIC being 1.41 µg/ml. The EOA showed 10.43, 12.35, and 3.92 µmol TE/ml at 90 µg/ml whereas the EOG showed 4.54, 8.94, and 3.43 µmol TE/ml at 88 µg/ml for ABTS, DPPH, and FRAP, respectively. Thus, the EOs demonstrated an effective action against foodborne pathogens and free radicals, indicative of their potential use as natural preservatives for foods. PRACTICAL APPLICATION: Guava and araçá are native Brazilian plants producers of essential oils, natural compounds with antimicrobial and antioxidant potential. The chemical composition of essential oils is responsible for its beneficial properties. The results demonstrated that the essential oils studied are rich in β-caryophyllene and has excellent activity against malefic microorganisms and free radicals, and can also be used as natural preservatives in foods.

Inhibitory effects of sodium new houttuyfonate on growth and biofilm formation of Streptococcus mutans

The present study aimed to assess the impact of sodium new houttuyfonate (SNH) on growth and biofilm formation of Streptococcus mutans, and the combinatorial effects of SNH with cariostatic agents. The effects of SNH on S. mutans planktonic cultures were assessed by growth curve assay. The effects of SNH on S. mutans biofilm and extracellular polysaccharides (EPS) production were observed via crystal violet (CV) assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, colony-forming unit (CFU) counting assay, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Quantitative real-time polymerase chain reaction (qPCR) was applied to investigate the regulatory effects of SNH on the expression of virulence genes of S. mutans. Checkerboard microdilution assay was performed to investigate the combinatorial effects of SNH with two common cariostatic agents. SNH acted as an inhibitor on planktonic cell growth, biofilm formation and EPS production of S. mutans. SNH also downregulated the expression of gtfBCD and comDE systems and exhibited synergism with chlorhexidine (CHX). In conclusion, this study indicated a possibility for SNH to become an anticaries agents by its antimicrobial activity and synergistic effects with CHX against S. mutans.

Brazilian southeast brown propolis: gas chromatography method development for its volatile oil analysis, its antimicrobial and leishmanicidal activities evaluation

INTRODUCTION

Propolis is widely used in folk medicine, and many factors can affect its chemical composition, including abiotic factors that can influence plants and bees. Therefore, analytical methods are powerful techniques in the quality control of such products.

OBJECTIVE

Develop and validate an analytical method for quantifying volatile compounds in Brazilian brown propolis, and evaluate its biological activities.

METHODS

A gas chromatography flame ionisation detector (GC-FID) analytical method was validated, attending the parameters of international validation guidelines as ANVISA 2017 and ICH 2005, for quantification of compounds present in volatile oils from propolis. Evaluation of cytotoxic, antimicrobial, and leishmanicidal activities of the oil.

RESULTS

The compounds 1,8-cineole, terpinen-4-ol, α-copaene, β-caryophyllene, γ-muurolene, nerolidol, spathulenol, and γ-palmitolactone were isolated from the volatile fraction of a Brazilian brown propolis and used in the method validation. All the validation parameters of the method were satisfactory. The volatile fraction displayed a significant leishmanicidal activity, with half maximal inhibition concentration (IC₅₀ ) = 21.3 μg/mL against amastigote forms and IC₅₀ = 25.1 μg/mL against promastigote forms of Leishmania amazonensis. The oil also displayed an antibacterial effect by inhibiting the growth of Streptococcus mutans and Staphylococcus aureus at 25 μg/mL and 50 μg/mL, respectively, but it was not cytotoxic against AGP-01, He-La and CHO-K1cell lines, with IC₅₀ > 100 μg/mL.

CONCLUSION

The GC-FID method can be a useful tool in the quality control of propolis material. The southeast brown propolis showed a high chemical complexity in its volatile fraction, which displayed leishmanicidal activity and bactericidal activity.

Candida albicans-The Virulence Factors and Clinical Manifestations of Infection

Candida albicans is a common commensal fungus that colonizes the oropharyngeal cavity, gastrointestinal and vaginal tract, and healthy individuals' skin. In 50% of the population, C. albicans is part of the normal flora of the microbiota. The various clinical manifestations of Candida species range from localized, superficial mucocutaneous disorders to invasive diseases that involve multiple organ systems and are life-threatening. From systemic and local to hereditary and environmental, diverse factors lead to disturbances in Candida's normal homeostasis, resulting in a transition from normal flora to pathogenic and opportunistic infections. The transition in the pathophysiology of the onset and progression of infection is also influenced by Candida's virulence traits that lead to the development of candidiasis. Oral candidiasis has a wide range of clinical manifestations, divided into primary and secondary candidiasis. The main supply of C. albicans in the body is located in the gastrointestinal tract, and the development of infections occurs due to dysbiosis of the residential microbiota, immune dysfunction, and damage to the muco-intestinal barrier. The presence of C. albicans in the blood is associated with candidemia-invasive Candida infections. The commensal relationship exists as long as there is a balance between the host immune system and the virulence factors of C. albicans. This paper presents the virulence traits of Candida albicans and clinical manifestations of specific candidiasis.

Essential Oils Biofilm Modulation Activity, Chemical and Machine Learning Analysis. Application on Staphylococcus aureus Isolates from Cystic Fibrosis Patients

Bacterial biofilm plays a pivotal role in chronic Staphylococcus aureus (S. aureus) infection and its inhibition may represent an important strategy to develop novel therapeutic agents. The scientific community is continuously searching for natural and "green alternatives" to chemotherapeutic drugs, including essential oils (EOs), assuming the latter not able to select resistant strains, likely due to their multicomponent nature and, hence, multitarget action. Here it is reported the biofilm production modulation exerted by 61 EOs, also investigated for their antibacterial activity on S. aureus strains, including reference and cystic fibrosis patients' isolated strains. The EOs biofilm modulation was assessed by Christensen method on five S. aureus strains. Chemical composition, investigated by GC/MS analysis, of the tested EOs allowed a correlation between biofilm modulation potency and putative active components by means of machine learning algorithms application. Some EOs inhibited biofilm growth at 1.00% concentration, although lower concentrations revealed different biological profile. Experimental data led to select antibiofilm EOs based on their ability to inhibit S. aureus biofilm growth, which were characterized for their ability to alter the biofilm organization by means of SEM studies.

Chemical Composition, Nutritional Value, and Biological Evaluation of Tunisian Okra Pods (Abelmoschus esculentus L. Moench)

The aim of this work was to perform an unprecedented in-depth study on the bioactive phytochemicals of Abelmoschus esculentus L. Moench Tunisian landrace (Marsaouia). For this purpose, its nutritional, aroma volatile, and phenolic profiles were characterized, and sundry biological activities were assessed in vitro. The approximate composition revealed that total dietary fiber as the most abundant macronutrient, mainly insoluble dietary fiber, followed by total carbohydrates and proteins. In addition, okra pods were rich in K, Ca, Mg, organic acids, tocopherols, and chlorophylls. Gas Chromatography-Electron Impact Mass Spectrometry (GC-EIMS) analysis showed that oxygenated monoterpenes, sesquiterpene hydrocarbons, and phenylpropanoids were the predominant essential volatile components in A. esculentus pods. A total of eight flavonols were detected by High-Performance Liquid Chromatography coupled to a DAD detector and mass spectrometry by electrospray ionization (HPLC-DAD-MS/ESI); with quercetin-3-O-glucoside being the majority phenolic component, followed by quercetin-O-pentosyl-hexoside and quercetin-dihexoside. This pioneering study, evidences that Tunisian okra display promising antioxidant and cytotoxic actions, in addition to relevant inhibitory effects against α-amylase and α-glucosidase enzymes, and interesting analgesic activity.

Effects of Cinnamon (Cinnamomum spp.) in Dentistry: A Review

Dental medicine is one of the fields of medicine where the most common pathologies are of bacterial and fungal origins. This review is mainly focused on the antimicrobial effects of cinnamon essential oil (EO), cinnamon extracts, and pure compounds against different oral pathogens and the oral biofilm and the possible effects on soft mouth tissue. Basic information is provided about cinnamon, as is a review of its antimicrobial properties against the most common microorganisms causing dental caries, endodontic and periodontal lesions, and candidiasis. Cinnamon EO, cinnamon extracts, and pure compounds show significant antimicrobial activities against oral pathogens and could be beneficial in caries and periodontal disease prevention, endodontics, and candidiasis treatment.

Antimicrobial Potential of Essential Oils from Cerrado Plants against Multidrug-Resistant Foodborne Microorganisms

Foodborne pathogens are a real public health concern in an escalating antimicrobial resistance scenario. Natural products represent a promising source of bioactive molecules, and essential oils have attracted much attention due to their myriad of biological properties, including antibacterial activities. In this context, essential oils obtained from the leaves of Chromolaena squalida, Campomanesia sessiliflora, Myrsine guianensis, Matayba guianensis, Siparuna guianensis, Ocotea minarum and Endlicheria paniculata—species from the Cerrado biome of Midwest Brazil—were extracted and evaluated for their antibacterial activity against a panel of four standard and three clinical multidrug−resistant bacterial strains. All tested oils showed moderate to good activity against at least four bacterial strains, including Salmonella Typhi and oxacillin−resistant Staphylococcus. The essential oils from C. squalida, C. sessiliflora, My. guianensis and Ma. guianensis showed strong inhibition of clinical Staphylococcus strains, which cause bovine mastitis and are related to milk−borne diseases. Their chemical profiles were investigated by gas chromatography coupled to mass spectrometry (GC/MS), which revealed a predominance of mono− and sesquiterpene hydrocarbons, some of which with well−known antimicrobial properties. The essential oil from Cerrado plants proved active against resistant Gram−positive and Gram−negative bacteria, revealing their potentialities for the development of new alternative agents to prevent the spreading of resistant bacterial contamination.

Cajuputs candy impairs Candida albicans and Streptococcus mutans mixed biofilm formation in vitro

Background: Cajuputs candy (CC), an Indonesian functional food, utilizes the bioactivity of Melaleuca cajuputi essential oil (MCEO) to maintain oral cavity health. Synergistic interaction between Candida albicans and Streptococcus mutans is a crucial step in the pathogenesis of early childhood caries. Our recent study revealed several alternative MCEOs as the main flavors in CC. The capacity of CC to interfere with the fungus-bacterium relationship remains unknown. This study aimed to evaluate CC efficacy to impair biofilm formation by these dual cariogenic microbes.

Methods: The inhibition capacity of CC against mixed-biofilm comprising C. albicans and S. mutans was assessed by quantitative (crystal violet assay, tetrazolium salt [MTT] assay, colony forming unit/mL counting, biofilm-related gene expression) and qualitative analysis (light microscopy and scanning electron microscopy).

Result: Both biofilm-biomass and viable cells were significantly reduced in the presence of CC. Scanning electron microscopy imaging confirmed this inhibition capacity, demonstrating morphology alteration of C. albicans, along with reduced microcolonies of S. mutans in the biofilm mass. This finding was related to the transcription level of selected biofilm-associated genes, expressed either by C. albicans or S. mutans. Based on qPCR results, CC could interfere with the transition of C. albicans yeast form to the hyphal form, while it suppressed insoluble glucan production by S. mutans. G2 derived from Mojokerto MCEO showed the greatest inhibition activity on the relationship between these cross-kingdom oral microorganisms (p < 0.05).

Conclusion: In general, all CC formulas showed biofilm inhibition capacity. Candy derived from Mojokerto MCEO showed the greatest capacity to maintain the yeast form of C. albicans and to inhibit extracellular polysaccharide production by S. mutans. Therefore, the development of dual-species biofilms can be impaired effectively by the CC tested.

Sequestration of Exogenous Volatiles by Plant Cuticular Waxes as a Mechanism of Passive Associational Resistance: A Proof of Concept

Numerous plant-derived volatile organic compounds (VOCs) induce the expression of resistance-related genes and thereby cause an "associational resistance" in neighbouring plants. However, VOCs can also be sequestered by plant cuticular waxes. In case that they maintain their biological activity, such sequestered VOCs could generate a "passive" associational resistance that is independent of any gene expression in the receiver. As a proof of concept, we used major components of the cuticular wax layers of the tree, Parkinsonia praecox, and conidia of Colletotrichum lindemuthianum, a fungal pathogen that has not been reported to infect P. praecox. Wax layers were re-constituted on glass slides and exposed to each of 20 pure VOCs for 1 d and then to ambient air for 1 d or 15 d. Gas chromatography-mass spectrometry (GC-MS) analyses showed that all 20 VOCs were sequestered by the re-constituted wax layers. Exposure to 18 of the VOCs significantly inhibited the germination of C. lindemuthianum conidia on these wax layers after 1 day of exposure to ambient air. Four of the VOCs: 4Z-heptenol, farnesene, limonene, and 2E-decenal, inhibited germination rates to less than 25% of the controls. After 15 d, all VOCs were still detectable, although at strongly reduced concentrations, and no significant inhibition of conidial germination could be detected anymore. Exogenous VOCs can be sequestered by the components of plant cuticular waxes and maintain their biological activity, at least over a certain time span: an effect that could generate a transient "passive associational resistance" to pathogens.

Management of Streptococcus mutans-Candida spp. Oral Biofilms' Infections: Paving the Way for Effective Clinical Interventions

Oral diseases are considered the most common noncommunicable diseases and are related to serious local and systemic disorders. Oral pathogens can grow and spread in the oral mucosae and frequently in biomaterials (e.g., dentures or prostheses) under polymicrobial biofilms, leading to several disorders such as dental caries and periodontal disease. Biofilms harbor a complex array of interacting microbes, increasingly unapproachable to antimicrobials and with dynamic processes key to disease pathogenicity, which partially explain the gradual loss of response towards conventional therapeutic regimens. New drugs (synthesized and natural) and other therapies that have revealed promising results for the treatment or control of these mixed biofilms are presented and discussed here. A structured search of bibliographic databases was applied to include recent research. There are several promising new approaches in the treatment of Candida spp.-Streptococcus mutans oral mixed biofilms that could be clinically applied in the near future. These findings confirm the importance of developing effective therapies for oral Candida-bacterial infections.

β-Caryophyllene: A Sesquiterpene with Countless Biological Properties

β-Caryophyllene (BCP), a natural bicyclic sesquiterpene, is a selective phytocannabinoid agonist of type 2 receptors (CB2-R). It isn’t psychogenic due to the absence of an affinity to cannabinoid receptor type 1 (CB1). Among the various biological activities, BCP exerts anti-inflammatory action via inhibiting the main inflammatory mediators, such as inducible nitric oxide synthase (iNOS), Interleukin 1 beta (IL-1β), Interleukin-6 (IL-6), tumor necrosis factor-alfa (TNF-α), nuclear factor kapp a-light-chain-enhancer of activated B cells (NF-κB), cyclooxygenase 1 (COX-1), cyclooxygenase 2 (COX-2). Peroxisome proliferator-activated receptors alpha (PPAR-α) effects are also mediated by the activation of PPAR-α and PPAR-γ receptors. In detail, many studies, in vitro and in vivo, suggest that the treatment with β-caryophyllene improves the phenotype of animals used to model various inflammatory pathologies, such as nervous system diseases (Parkinson’s disease, Alzheimer’s disease, multiple sclerosis, amyotrophic lateral sclerosis, stroke), atherosclerosis, and tumours (colon, breast, pancreas, lymphoma, melanoma and glioma cancer). Furthermore, pre-clinical data have highlighted that BCP is potentially useful in Streptococcus infections, osteoporosis, steatohepatitis, and exerts anticonvulsant, analgesic, myorelaxing, sedative, and antidepressive effects. BCP is non-toxic in rodents, with a Lethal dose, 50% (LD50) greater than 5000 mg/kg. Nevertheless, it inhibits various cytochrome P450 isoforms (above all, CYP3A4), which metabolise xenobiotics, leading to adverse effects, due to drug levels over therapeutic window. All the reported data have highlighted that both pharmacological and toxicological aspects need to be further investigated with clinical trials.

Effects of nano-hydroxyapatite on the formation of biofilms by Streptococcus mutans in two different media

OBJECTIVES

The aim of this study was to examine the effect of nano-hydroxyapatite (nHA) on biofilm formation by Streptococcus mutans, which is actively involved in the initiation of dental caries.

DESIGN

The effects of nHA on growth and biofilm formation by S. mutans were investigated in two media: a saliva analog medium, basal medium mucin (BMM); and a nutrient-rich medium, brain heart infusion (BHI); in the presence and absence of sucrose.

RESULTS

Sucrose enhanced the growth of S. mutans in both media. In the presence of sucrose, nHA enhanced bacterial growth and biofilm formation more in BMM medium than in BHI. nHA also affected the transcription of glucosyltransferase (gtf) genes and production of polysaccharide differently in the two media. In BHI medium, the transcription of all three gtf genes, coding for enzymes that synthesize soluble and insoluble glucans from sucrose, was increased more than 3-fold by nHA. However, in BMM medium, only the transcription of gtfB and gtfC, coding for insoluble glucans, was substantially enhanced by nHA.

CONCLUSIONS

nHA appeared to enhance biofilm formation by increasing glucosyltransferase transcription, which resulted in an increase in production of insoluble glucans. This effect was influenced by the growth conditions.

Inhibition of Streptococcus mutans and S. sobrinus biofilms by liamocins from Aureobasidium pullulans

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Liamocins are polyol lipids that specifically inhibit Streptococcus spp..

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Liamocins inhibited biofilms of S. mutans and S. sobrinus in MTP assays.

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MTP results were verified in biofilm flow cell assays.

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Liamocins are potential new inhibitors of oral streptococcal biofilms.

The aim of this study was to determine if the novel anti-streptococcal inhibitors, liamocins, also inhibit biofilm formation by S. mutans and S. sobrinus. S. mutans strain ATCC 25175 and S. sobrinus strain ATCC 33478 were tested for biofilm formation in a rapid microtiter plate (MTP) assay and the effects of added liamocins were determined. This assay measures relative biofilm growth on pin lids. Results were verified in a biofilm flow cell assay, using hydroxyapatite-coated coupons to simulate dental material. Planktonic cultures of S. mutans and S. sobrinus were inhibited by 0.1 mg liamocins/ml. When liamocins were added after the adhesion phase in a rapid microtiter plate assay, S. mutans was inhibited 53% by 5 mg liamocins/ml, while S. sobrinus was more sensitive, showing 100% inhibition at 0.5 mg liamocins/ml. When liamocins were added during the adhesion phase, biofilms of S. mutans showed 78% inhibition at 3.0 mg liamocins/ml. In a biofilm flow cell assay, liamocins added after the adhesion phase at 0.5 mg liamocins/ml inhibited biofilms of S. sobrinus, and appeared to remove biofilms over time. Liamocins were shown for the first time to inhibit biofilm formation by S. mutans and S. sobrinus. Since liamocins are specific for Streptococcus spp., they are potential new inhibitors of oral streptococcal biofilms that should not affect normal oral microflora.