Systematic screening of plant extracts from the Brazilian Pantanal with antimicrobial activity against bacteria with cariogenic relevance

Cymbopogon citratus Essential Oil Increases the Effect of Digluconate Chlorhexidine on Microcosm Biofilms

The aim of this study was to evaluate the effect of the Cymbopogon citratus essential oil and its association with chlorhexidine on cariogenic microcosm biofilm composition and acidogenicity. Minimum inhibitory and bactericide concentrations from the essential oil and chlorhexidine were determined by broth microdilution assay. Microcosms (polymicrobial) biofilms were produced on glass coverslips, using inoculum from human saliva in McBain culture medium (0.5% sucrose exposure for 6 h/day) for 3 days in 24-well plates. The biofilms were treated twice a day and their composition was evaluated by microorganism quantification. The acidogenicity was evaluated by measuring the pH of the spent culture medium in contact with the biofilm. Overall, the association of C. citratus and chlorhexidine reduced total bacterial counts and aciduric bacteria (maximum reduction of 3.55 log UFC/mL) in microcosm biofilms. This group also presented the lowest acidogenicity even when exposed to sucrose-containing medium. C. citratus essential oil increases the effect of digluconate chlorhexidine on microcosm biofilms. Based on these findings, this study can contribute to the development of new formulations that might allow for the use of mouthwashes for a shorter period, which may reduce undesirable effects and increase patient compliance to the treatment.

Antibiotics: Conventional Therapy and Natural Compounds with Antibacterial Activity-A Pharmaco-Toxicological Screening

Antibiotics are considered as a cornerstone of modern medicine and their discovery offers the resolution to the infectious diseases problem. However, the excessive use of antibiotics worldwide has generated a critical public health issue and the bacterial resistance correlated with antibiotics inefficiency is still unsolved. Finding novel therapeutic approaches to overcome bacterial resistance is imperative, and natural compounds with antibacterial effects could be considered a promising option. The role played by antibiotics in tumorigenesis and their interrelation with the microbiota are still debatable and are far from being elucidated. Thus, the present manuscript offers a global perspective on antibiotics in terms of evolution from a historical perspective with an emphasis on the main classes of antibiotics and their adverse effects. It also highlights the connection between antibiotics and microbiota, focusing on the dual role played by antibiotics in tumorigenesis. In addition, using the natural compounds with antibacterial properties as potential alternatives for the classical antibiotic therapy is discussed.

Antibiofilm effects of Thymus vulgaris and Hyptis spicigera essential oils on cariogenic bacteria

Aim: The inhibitory and antibiofilm effects of Thymus vulgaris (EOTv) and Hyptis spicigera essential oils (EOHs) on cariogenic microorganisms were evaluated. Materials & methods: The chemical characterization of EOTv was performed by gas chromatography/mass spectrometry. Streptococcus mutans, Streptococcus gordonii, Streptococcus sanguinis, Streptococcus mitis, Streptococcus sobrinus, Lactobacillus acidophilus and Actinomyces naeslundii were used for agar diffusion assays and determination of minimal inhibitory and minimal bactericide concentrations. In addition, 20 streptococci and lactobacilli clinical isolates were also tested. The effects of essential oil on microbial initial biofilm formation and on preformed microcosm biofilm formed from human saliva were studied. Results & conclusion: Both essential oils had inhibitory effects on the cariogenic species and reduced the bacterial adherence to dental enamel. Essential oils were able to disrupt preformed microcosm biofilms. Thymus vulgaris and Hyptis spicigera essential oils have potential to be used in the development of formulations to the control of cariogenic biofilms.

Ellagic Acid-Cyclodextrin Complexes for the Treatment of Oral Candidiasis

The increase in the prevalence of fungal infections worldwide and the rise in the occurrence of antifungal resistance suggest that new research to discover antifungal molecules is needed. The aim of this study was to evaluate the potential use of ellagic acid–cyclodextrin complexes (EA/HP-β-CD) for the treatment of oral candidiasis. First, the effect of EA/HP-β-CD on C. albicans planktonic cells and biofilms was evaluated. Then, the cytotoxicity of the effective concentration was studied to ensure safety of in vivo testing. Finally, the in vivo effectiveness was determined by using a murine model of induced oral candidiasis. Data was statistically analyzed. The minimal inhibitory concentration of EA/HP-β-CD was 25 µg/mL and a concentration of 10 times MIC (250 µg/mL) showed an inhibitory effect on C. albicans 48 h-biofilms. The complex at concentration 250 µg/mL was classified as slightly cytotoxic. In vivo experiments showed a reduction in fungal epithelial invasion after treatment with EA/HP-β-CD for 24 h and 96 h when compared to the negative control. In conclusion, the results demonstrated that EA/HP-β-CD has antifungal and anti-inflammatory effects, reducing the invasive capacity of C. albicans, which suggests that EA/HP-β-CD may be a promising alternative for the treatment of oral candidiasis.

The genus Jatropha (Euphorbiaceae): A review on secondary chemical metabolites and biological aspects

The genus Jatropha belongs to the Euphorbiaceae family and has about 175 species. Originally from tropical America, the Jatropha genus can be found all over the tropics and subtropics of Asia and Africa. Jatropha species are recognized to be important sources of secondary metabolites with a broad spectrum of biological functions. Extracts and isolated compounds from species of this genus have been known to have properties of cytotoxicity, antimicrobial, antifungal, anti-inflammatory, antioxidant, insecticidal, larvicidal, inhibition AChE, and toxicity activities. Investigations on the chemical aspects of the genus Jatropha have led to the identification of cyclic peptides, lignans, flavonoids, coumarins, alkaloids, eudesmenoic acids, and mainly terpenes. In this review, we provide a comprehensive picture of the phytochemical and biological characteristics of Jatropha species. The information gathered and approached in this paper might support the planning and discussion of future studies on the topic.

Streptococcus mutans and Actinomyces naeslundii Interaction in Dual-Species Biofilm

The study of bacterial interaction between Streptococcus mutans and Actinomyces naeslundii may disclose important features of biofilm interspecies relationships. The aim of this study was to characterize-with an emphasis on biofilm formation and composition and metabolic activity-single- and dual-species biofilms of S. mutans or A. naeslundii, and to use a drip flow reactor (DFR) to evaluate biofilm stress responses to 0.2% chlorhexidine diacetate (CHX). Single- and dual-species biofilms were grown for 24 h. The following factors were evaluated: cell viability, biomass and total proteins in the extracellular matrix, 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide-"XTT"-reduction and lactic acid production. To evaluate stress response, biofilms were grown in DFR. Biofilms were treated with CHX or 0.9% sodium chloride (NaCl; control). Biofilms were plated for viability assessment. Confocal laser-scanning microscopy (CLSM) was also performed. Data analysis was carried out at 5% significance level. S. mutans viability and lactic acid production in dual-species biofilms were significantly reduced. S. mutans showed a higher resistance to CHX in dual-species biofilms. Total protein content, biomass and XTT reduction showed no significant differences between single- and dual-species biofilms. CLSM images showed the formation of large clusters in dual-species biofilms. In conclusion, dual-species biofilms reduced S. mutans viability and lactic acid production and increased S. mutans' resistance to chlorhexidine.

Mouthwash containing Croton doctoris essential oil: in vitro study using a validated model of caries induction

Aim: To validate an in vitro caries model and to evaluate an experimental mouthwash containing Croton doctoris essential oil.  Materials & methods: To validate the experimental model, we used McBain medium and polymicrobial biofilms. The EOM (essential oil mouthwash) was tested using the validated model. Microbial composition (colony-forming unit/ml), acidogenicity, enamel demineralization (percentage of surface enamel hardness loss), cytotoxicity and essential oil composition were evaluated. Results: The model was validated with 0.5% sucrose, duration of 4 days and treatments twice per day. There were statistically significant differences between the EOM, the negative control and chlorhexidine mouthwash in colony-forming unit/ml and percentage of surface enamel hardness loss. Cytotoxicity was similar to that of chlorhexidine mouthwash.  A total of 66.11% of the essential oil consists of sesquiterpenes. Conclusion: The experimental mouthwash showed antimicrobial activity against polymicrobial biofilms and reduced enamel demineralization.

Screening of plants with antimicrobial activity against enterobacteria, Pseudomonas spp. and Staphylococcus spp

AIM

This study screened plants for antibacterial properties against bacteria of medical importance.

MATERIALS & METHODS

60 extracts were obtained from the leaves of ten plants (Jatropha weddelliana, Attalea phalerata, Buchenavia tomentosa, Croton doctoris, Mouriri elliptica, Mascagnia benthamiana, Senna aculeata, Unonopis guatterioides, Allagoptera leucocalyx and Bactris glaucescens) using different extraction methods: A) Ethanol 70°C/72 h; B) Water/5 min/100°C; C) Water/1 h/55°C; D) Water/72 h; E) Hexane/72 h and F) Ethanol 99°C/72 h. Enterobacteria/Pseudomonas and staphylococci reference strains and 201 clinical isolates were used. Primary screening was done using agar well-diffusion assay. MIC/minimum bactericidal concentration and chemical characterization were determined.

RESULTS

Extracts 5F and 3A showed the best MIC/minimum bactericidal concentration against clinical isolates and showed the presence of phenols.

CONCLUSION

The present study demonstrated that Mouriri elliptica and Buchenavia tomentosa were the most active plants against the studied bacteria.

Plant extracts: initial screening, identification of bioactive compounds and effect against Candida albicans biofilms

AIM

This study screened plants from Brazilian Pantanal for Candida albicans antibiofilm activity.

MATERIAL & METHODS

Sixty extracts were obtained from ten plants using different extraction methods. Antifungal activity was assessed. Effects on biofilm inhibition and disruption and cytotoxicity were also evaluated. The most active extract was chemically characterized.

RESULTS

Buchenavia tomentosa ethanolic extract showed noticeable antifungal activity and was selected for biofilm experiments. Subinhibitory concentration of extract inhibited fungal adhesion. Maximum killing reached 90% of C. albicans cells in suspension and 65% of cells in biofilms. The active extract was noncytotoxic. Chemical characterization showed the presence of phenols. Ellagic and gallic acids showed activity on C. albicans.

CONCLUSION

B. tomentosa extract and its isolated compound, ellagic acid, presented antibiofilm activity and low toxicity.

Antifungal activity of extracts and isolated compounds from Buchenavia tomentosa on Candida albicans and non-albicans

AIM

This study aimed to evaluate the antifungal activity of Buchenavia tomentosa extract and bioactive compounds on six Candida species.

MATERIALS & METHODS

The antimicrobial activity of extract was evaluated using standard strains and clinical isolates. Cytotoxicity was tested in order to evaluate cell damage caused by the extract. Extract was chemically characterized and the antifungal activity of its compounds was evaluated.

RESULTS

Extract showed antifungal activity on Candida species. Candida non-albicans were more susceptible than Candida albicans. Low cytotoxicity for extract was observed. The isolated compounds presented antifungal activity at least against one Candida spp. and all compounds presented antifungal effect on Candida glabrata.

CONCLUSION

Extracts from Buchenavia tomentosa showed promising antifungal activity on Candida species with low cytotoxicity. Gallic acid, corilagin and ellagic acid showed promising inhibitory activity on Candida glabrata.

Cariogram outcome after 90 days of oral treatment with Streptococcus salivarius M18 in children at high risk for dental caries: results of a randomized, controlled study

Dental caries is the most common chronic disease of childhood. Cariogram is a well-recognized algorithm-based software program based on different caries-related risk factors and intended to aid clinicians in performing more objective and consistent dental caries risk assessments. This type of approach precedes the diagnosis of caries and allows the dentist to identify at-risk patients and then take appropriate preventive measures before caries develop further. One of the etiological factors favoring the development of dental caries is the mutans streptococci. These acidogenic dental plaque inhabitants can be effectively antagonized by the activity of bacteriocins released by the probiotic Streptococcus salivarius M18 (salivarius M18). Moreover, salivarius M18 after colonizing the human oral mucosa produces the enzymes dextranase and urease that are able to counteract plaque formation and saliva acidity, respectively. Seventy-six subjects at high risk of dental caries were randomized and then either treated or not treated for 90 days with an oral formulation containing the oral probiotic salivarius M18 (Carioblis(®)). The results indicate that the use of salivarius M18 increases the chances of avoiding new dental caries development in children, and its application could be proposed as a new tool in the dentist's armory to be adopted in subjects considered at high risk on the basis of their Cariogram outcome.