Structure-Metabolism Relationships of benzimidazole derivatives with anti-Trypanosoma cruzi activity for Chagas disease.

This study introduces further insights from the hit-to-lead optimization process involving a series of benzimidazole derivatives acting as inhibitors of the cruzain enzyme, which targets Trypanosoma cruzi, the causative parasite of Chagas disease. Here, we present the design, synthesis and biological evaluation of 30 new compounds as a third generation of benzimidazole analogues with trypanocidal activity, aiming to enhance our understanding of their pharmacokinetic profiles and establish a structure-metabolism relationships within the series. The design of these new analogues was guided by the analysis of previous pharmacokinetic results, considering identified metabolic sites and biotransformation studies. This optimization resulted in the discovery of two compounds (42e and 49b) exhibiting enhanced metabolic stability, anti-Trypanosoma cruzi activity compared to benznidazole (the reference drug for Chagas disease), as well as being non-cruzain inhibitors, and demonstrating a satisfactory in vitro pharmacokinetic profile. These findings unveil a new subclass of aminobenzimidazole and rigid compounds, which offer potential for further exploration in the quest for discovering novel classes of antichagasic compounds.

Evaluation and discovery of novel benzothiazole derivatives as promising hits against Leishmania infantum.

An early exploration of the benzothiazole class against two kinetoplastid parasites, Leishmania infantum and Trypanosoma cruzi, has been performed after the identification of a benzothiazole derivative as a suitable antileishmanial initial hit. The first series of derivatives focused on the acyl fragment of its class, evaluating diverse linear and cyclic, alkyl and aromatic substituents, and identified two other potent compounds, the phenyl and cyclohexyl derivatives. Subsequently, new compounds were designed to assess the impact of the presence of diverse substituents on the benzothiazole ring or the replacement of the endocyclic sulfur by other heteroatoms. All compounds showed relatively low cytotoxicity, resulting in decent selectivity indexes for the most active compounds. Ultimately, the in vitro ADME properties of these compounds were assessed, revealing a satisfying water solubility, gastrointestinal permeability, despite their low metabolic stability and high lipophilicity. Consequently, compounds 5 and 6 were identified as promising hits for further hit-to-lead exploration within this benzothiazole class against L. infantum, thus providing promising starting points for the development of antileishmanial candidates.

Structure-activity relationships of novel N-imidazoylpiperazines with potent anti-Trypanosoma cruzi activity.

Background: Chagas disease is caused by the parasite Trypanosoma cruzi, and the lack of effective and safe treatments makes identifying new classes of compounds with anti-T. cruzi activity of paramount importance. Methods: Hit-to-lead exploration of a metabolically stable N-imidazoylpiperazine was performed. Results: Compound 2, a piperazine derivative active against T. cruzi, was selected to perform the hit-to-lead exploration, which involved the design, synthesis and biological evaluation of 39 new derivatives. Conclusion: Compounds 6e and 10a were identified as optimized compounds with low micromolar in vitro activity, low cytotoxicity and suitable preliminary absorption, distribution, metabolism and excretion and physicochemical properties. Both compounds reduced parasitemia in mouse models of Chagas disease, providing a promising opportunity for further exploration of new antichagasic compounds.

Morphological changes and viability of Streptococcus mutans biofilm treated with erythrosine: A confocal laser scanning microscopy analysis.

Antimicrobial photodynamic therapy (a-PDT) is a modality that aims to induce microorganisms through visible light, a photosensitizer, and molecular oxygen. This therapy has shown promising results in controlling cariogenic biofilm in vitro and in vivo counterparts. This study investigated bacterial viability and morphological characterization of Streptococcus mutans mature biofilms after combination of erythrosine and a high potency dental curing light. Biofilms were formed on saliva-coated hydroxyapatite disks in batch culture. The samples were performed in triplicates. Fresh medium was replaced daily for five days and treated using 40 µM of E activated by HL 288 J/cm2 and total dose of 226 J at 1200 mW/cm2. Phosphate buffer saline and 0.12% of chlorhexidine were used as negative and positive control, respectively. After treatment, biofilms were assessed for microbial viability and morphological characterization by means of bio-volume and thickness. COMSTAT software was used for image analysis. Data were analyzed using two-way ANOVA followed by Tukey test with significance level 5%. The application of a-PDT and CHX treatments decreased S. mutans bacterial viability. The image analysis showed more red cells on biofilms when compared to other groups, demonstrating photobacterial killing. Erythrosine irradiated with a high potency curing light can potentially act as an antimicrobial tool in the treatment of cariogenic biofilms. The morphology and viability of microorganisms were impacted after treatment. Treatment with photodynamic therapy may be able to reduce the bio-volume and viability of bacteria present in biofilms. CLINICAL RELEVANCE AND RESEARCH HIGHLIGHTS: The use of the a-PDT technique has been applied in dentistry with satisfactory results. Some applications of this technique are in stomatology and endodontics. In the present study, we sought to understand the use of photodynamic therapy in the control of biofilm and the results found are compatible with the objective of microbiological control proposed by this technique, thus raising the alert for future studies in vivo using the combination of a-PDT with erythrosine, since they are easily accessible materials for the dental surgeon and can be applied in clinical practice.

Effect of titanium dioxide on Streptococcus mutans biofilm.

BACKGROUND: Streptococcus mutans (S. mutans) participates in the dental caries process. Titanium dioxide (TiO2) nanoparticles produce reactive oxygen species capable of disrupting bacterial DNA synthesis by creating pores in cell walls and membranes. OBJECTIVE: The objective of this study was to determine the effect of TiO2 on the disruption of S. mutans biofilm. METHODS: This study was conducted in four phases involving a TiO2-containing toothbrush and TiO2 nanoparticles. Each phase was completed using 24 h established S. mutans biofilm growth. Phase one data was collected through a bacterial plating study, assessing biofilm viability. Biofilm mass was evaluated in phase two of the study by measuring S. mutans biofilm grown on microtiter plates following crystal violet staining. The third phase of the study involved a generalized oxygen radical assay to determine the relative amount of oxygen radicals released intracellularly. Phase four of the study included the measurement of insoluble glucan/extracellular polysaccharide (EPS) synthesis using a phenol-sulfuric acid assay. RESULTS: Both exposure time and time intervals had a significant effect on bacterial viability counts (p = 0.0323 and p = 0.0014, respectively). Bacterial counts after 6 min of exposure were significantly lower than after 2 min (p = 0.034), compared to the no treatment control (p = 0.0056). As exposure time increased, the amount of remaining biofilm mass was statistically lower than the no treatment control. Exposure time had a significant effect on oxygen radical production. Both the 30 and 100 nm TiO2 nanoparticles had a significant effect on bacterial mass. The silver nanoparticles and the 30 and 100 nm TiO2 nanoparticles significantly inhibited EPS production. CONCLUSION: The TiO2-containing toothbrush kills, disrupts, and produces oxygen radicals that disrupt established S. mutans biofilm. TiO2 and silver nanoparticles inhibit EPS production and reduce biofilm mass. The addition of TiO2 to dental products may be effective in reducing cariogenic dental biofilm.

Comparison of In Vitro Biofilm Formation on Titanium and Zirconia Implants.

Background: Peri-implant diseases are emerging issues in contemporary implant dentistry. As biofilms play a critical role in peri-implant diseases, the characteristic of resisting bacterial adhesion would be ideal for dental implants. The aims of the study were to compare titanium (Ti) and zirconia (Zr) implants regarding the amount of biofilm formation at different time frames and assess the distribution of biofilm on different aspects of dental implants. Methods: Biofilm was developed on Ti and Zr dental implants with a peri-implant-related multispecies model with Streptococcus oralis, Actinomyces naeslundii, Veillonella dispar, and Porphyromonas gingivalis, for 3 and 14 days. Quantitative assessment was performed with the measurement of total bacterial viability (colony forming units, CFU/mg). Scanning electron microscopy (SEM) was used to evaluate biofilm formation on different aspects of the implants. Results: Three-day-old biofilm on Ti implants was significantly higher than that on Zr implants (p < 0.001). The Ti and Zr groups were not significantly different for 14-day-old biofilm. SEM images demonstrated that 3-day-old biofilm on Zr implants was sparse while biofilm growth was more pronounced for 3-day-old biofilm on Ti implants and 14-day-old biofilm groups. It appeared that less biofilm formed on the valley compared to the thread top for 3-day-old biofilm on Zr implants. Differences between the valley and the thread top became indistinguishable with the development of mature biofilm. Conclusion: While early formed biofilms show greater accumulation on Ti implants compared to Zr implants, older biofilms between the two groups are comparable. The distribution of biofilms was not uniform on different areas of implant threads during early biofilm development.

Physical, Mechanical, and Anti-Biofilm Formation Properties of CAD-CAM Milled or 3D Printed Denture Base Resins: In Vitro Analysis.

PURPOSE: To investigate surface characteristics (roughness and contact angle), anti-biofilm formation, and mechanical properties (mini-flexural strength) of computer-aided design and computer-aided manufacturing (CAD-CAM) polymethylmethacrylate (PMMA) polymer, and three-dimensional (3D) printed resin for denture base fabrication compared with conventional heat polymerized denture base resins. MATERIALS AND METHODS: A total of 60 discs and 40 rectangular specimens were fabricated from one CAD-CAM (AvaDent), one 3D printed (Cosmos Denture), and two conventional heat polymerized (Lucitone 199 and VipiWave) materials for denture base fabrication. Roughness was determined by Ra value; the contact angle was measured by the sessile drop method. The biofilm formation inhibition behavior was analyzed through Candida albicans adhesion, while mini-flexural strength test was done using a three-point bending test. The data were analyzed using descriptive and analytical statistics (α = 0.05). RESULTS: The CAD-CAM PMMA group showed the lowest C. albicans adhesion (log CFU/mL: 3.74 ± 0.57) and highest mini-flexural strength mean (114.96 ± 16.23 MPa). 3D printed specimens presented the highest surface roughness (Ra: 0.317 ± 0.151 µm) and lowest mini-flexural strength values (57.23 ± 9.07 MPa). However, there was no statistical difference between CAD-CAM PMMA and conventional groups for roughness, contact angle, and mini-flexural strength. CONCLUSIONS: CAD-CAM milled materials present surface and mechanical properties similar to conventional resins and show improved behavior in preventing C. albicans adhesion. Nevertheless, 3D printed resins present decreased mini-flexural strength.

Hit-to-lead optimization of a 2-aminobenzimidazole series as new candidates for chagas disease.

Chagas disease is a neglected tropical disease caused by Trypanosoma cruzi. Because current treatments present several limitations, including long duration, variable efficacy and serious side effects, there is an urgent need to explore new antitrypanosomal drugs. The present study describes the hit-to-lead optimization of a 2-aminobenzimidazole hit 1 identified through in vitro phenotypic screening of a chemical library against intracellular Trypanosoma cruzi amastigotes, which focused on optimizing potency, selectivity, microsomal stability and lipophilicity. Multiparametric Structure-Activity Relationships were investigated using a set of 277 derivatives. Although the physicochemical and biological properties of the initial hits were improved, a combination of low kinetic solubility and in vitro cytotoxicity against mammalian cells prevented progression of the best compounds to an efficacy study using a mouse model of Chagas disease.

Impact of curcumin loading on the physicochemical, mechanical and antimicrobial properties of a methacrylate-based experimental dental resin.

Oral biofilms are directly linked to one of the most common chronic human diseases, dental caries. Resin-based dental materials have significant potential to replace amalgam, however they lack sufficient antimicrobial power. This innovative study investigates a curcumin-loaded dental resin which can be utilized in an antimicrobial photodynamic therapy (aPDT) approach. The study evaluated the effects of curcumin loading on resin physicochemical, mechanical, and adhesive properties, as well as the antimicrobial response associated with blue light activation. Preliminary tests involving degree of conversion (DC) and sample integrity determined the optimal loading of curcumin to be restricted to 0.05 and 0.10 wt%. These optimal loadings were tested for flexural strength (FS), water sorption (WS) and solubility (SL), shear bond strength to dentin (SBS), and viability of Streptococcus mutans under 14.6 J/cm2 blue light or dark conditions, in 6 h and 24 h biofilms. The results demonstrated that 0.10 wt% curcumin had minimal impact on either FS or SBS, but detectably increased WS and SL. A 2 log10 (CFU/mL) reduction in S. mutans after light application in both 6 h and 24 h biofilms were corroborated by CLSM imaging and highlighted the significant potential of this novel aPDT approach with resin-based dental materials.

Effect of curcumin-loaded photoactivatable polymeric nanoparticle on peri-implantitis-related biofilm.

Curcumin has been used as a photosensitizer (PS) for antimicrobial photodynamic chemotherapy (PACT). However, its low solubility, instability, and poor bioavailability challenge its in vivo application. This study aimed to synthesize curcumin-loaded polymeric nanoparticles (curcumin-NP) and determine their antimicrobial and cytotoxic effects. Nanoparticles (NP) were synthesized using polycaprolactone (PCL) as a polymer by the nanoprecipitation method. Curcumin-NP was characterized by particle size, polydispersity index and zeta potential, scanning electron microscopy, and curcumin encapsulation efficiency (EE). Curcumin-NP was compared to free curcumin solubilized in 10% DMSO as photosensitizers for PACT in single and multispecies Porphyromonas gingivalis, Fusobacterium nucleatum, and Streptococcus oralis biofilms. Chlorhexidine 0.12% (CHX) and ultrapure water were used as positive and negative controls. The cytotoxic effect of curcumin-NP was evaluated on human periodontal ligament fibroblast cells (HPLF). Data were analyzed by ANOVA (α=0.05). Curcumin-NP exhibited homogeneity and stability in solution, small particle size, and 67.5% EE of curcumin. Curcumin-NP presented reduced antibiofilm activity at 500 µg/ml, although in planktonic cultures it showed inhibitory and bactericidal effect. Curcumin-NP and curcumin with and without photoactivation were not cytotoxic to HPLF cells. Curcumin-NP has antimicrobial and antibiofilm properties, with better effects when associated with blue light, being a promising therapy for preventing and treating peri-implant diseases.

In-vitro evaluation of the anti-cariogenic effect of a hybrid coating associated with encapsulated sodium fluoride and stannous chloride in nanoclays on enamel.

OBJECTIVE: The aim of this study is to test, in vitro, the anti-cariogenic effect of experimental hybrid coatings, with nano clays of halloysite or bentonite, loaded with sodium fluoride or with a combination of sodium fluoride and stannous chloride, respectively. METHODOLOGY: The varnish Fluor Protector (1,000 ppm of F-) was used as positive control and no treatment was the negative control. Enamel specimens (5 mm × 5 mm) were obtained from bovine teeth. The specimens (n=10) had their surfaces divided into two halves (5 mm × 2.5 mm each), in which one half received one of the treatments (Hybrid; Hybrid + NaF; Hybrid + NaF + SnCl2; Hybrid + NaF Loaded; Hybrid + NaF + SnCl2 Loaded). The specimens were submitted to a cariogenic challenge using a biofilm model (S. mutans UA159, for 5 days). Enamel surfaces both under and adjacent to the treated area were analyzed for mineral loss and lesion depth, by transverse microradiography. The pH of the medium was measured twice a day, and the fluoride release was analyzed. Additional specimens were submitted to confocal analysis. RESULTS: Data were statistically analyzed by two-way ANOVA followed by Tukey test (α=0.05). None of hybrid groups were able to reduce the lesion depth; the Hybrid + NaF group, however, was able to reduce mineral loss differing from the negative control (p=0.008). The groups showed no significant difference in the pH measurement and fluoride release. Confocal analysis confirmed that for all groups the biofilm growth was similar. CONCLUSION: None of the hybrid groups reduced lesion depth, but the Hybrid + NaF group was able to promote protection against mineral loss.

Low-Temperature Plasma Short Exposure to Decontaminate Peri-Implantitis-Related Multispecies Biofilms on Titanium Surfaces In Vitro.

Background: The use of low-temperature plasma (LTP) is a novel approach to treating peri-implantitis. LTP disrupts the biofilm while conditioning the surrounding host environment for bone growth around the infected implant. The main objective of this study was to evaluate the antimicrobial properties of LTP on newly formed (24 h), intermediate (3 days), and mature (7 days) peri-implant-related biofilms formed on titanium surfaces. Methods: Actinomyces naeslundii (ATCC 12104), Porphyromonas gingivalis (W83), Streptococcus oralis (ATCC 35037), and Veillonella dispar (ATCC 17748) were cultivated in brain heart infusion supplemented with 1% yeast extract, hemin (0.5 mg/mL), and menadione (5 mg/mL) and kept at 37°C in anaerobic conditions for 24 h. Species were mixed for a final concentration of ~105 colony forming units (CFU)/mL (OD = 0.01), and the bacterial suspension was put in contact with titanium specimens (7.5 mm in diameter by 2 mm in thickness) for biofilm formation. Biofilms were treated with LTP for 1, 3, and 5 min at 3 or 10 mm from plasma tip to sample. Controls were those having no treatment (negative control, NC) and argon flow under the same LTP conditions. Positive controls were those treated with 14 µg/mL amoxicillin and 140 µg/mL metronidazole individually or combined and 0.12% chlorhexidine (n = 6 per group). Biofilms were evaluated by CFU, confocal laser scanning microscopy (CLSM), and fluorescence in situ hybridization (FISH). Comparisons among bacteria; 24 h, 3-day, and 7-day biofilms; and treatments for each biofilm were made. Wilcoxon signed-rank and Wilcoxon rank sum tests were applied (α = 0.05). Results: Bacterial growth was observed in all NC groups, corroborated by FISH. LTP treatment significantly reduced all bacteria species compared to the NC in all biofilm periods and treatment conditions (p ≤ 0.016), and CLSM corroborated these results. Conclusion: Within the limitation of this study, we conclude that LTP application effectively reduces peri-implantitis-related multispecies biofilms on titanium surfaces in vitro.

Effect of blue light plus chlorhexidine therapy on Streptococcus mutans biofilm and its regrowth in an in vitro orthodontic model.

INTRODUCTION: Fixed orthodontic appliances create areas of stagnation for dental biofilms and make it difficult to clean the teeth; therefore, there is a risk of developing incipient caries lesions during the orthodontic treatment. The objective of this study is to determine if the combination of 2 different therapies, phototherapy by blue light (BL) and the antimicrobial 0.12% chlorhexidine (CHX) on enamel, orthodontic brackets, and elastics, would reduce or inhibit mature Streptococcus mutans biofilms and their regrowth on these substrates 24 hours after the application of the treatment; and if this treatment would interfere with bracket adhesion to the enamel. METHODS: Biofilms of S. mutans UA159 were formed for 5-days over samples composed of a bovine enamel, orthodontic bracket, and orthodontic elastic. Then, the specimens were treated with 0.89% NaCl for 1 minute, BL for 12 minutes (72 J/cm2), 0.12% CHX for 1 minute, and BL for 12 minutes, followed by 0.12% CHX for 1 minute (BL+CHX). Biofilm was evaluated by colonies forming units and dry weight immediately after treatments and 24 hours after treatments (regrowth). The pH of the spent media was measured on the fifth and sixth days. Biofilm formation on the samples after the treatments and regrowth was visually evaluated by confocal laser scanning microscopy. Shear bond strength (SBS) between bracket and enamel was evaluated using a universal testing machine at a crosshead speed of 1 mm/min. After bonding, specimens were thermocycled (500× at 5-55°C), treated, and thermocycled again. RESULTS: After 5 days of biofilm formation, BL+CHX significantly reduced the bacterial viability on enamel compared with NaCl (P = 0.004) and BL (P = 0.014). For bracket and elastic, all the treatments resulted in similar bacterial viability (P ≥0.081). In the regrowth, CHX and BL+CHX significantly reduced the bacterial viability in the enamel compared with the NaCl (P ≤0.015) and BL (P ≤0.013). For bracket, BL+CHX significantly reduced the bacterial viability compared with NaCl (P = 0.008) and BL (P = 0.009). For the elastic, BL+CHX eliminated the biofilms from the substrate. CHX and BL+CHX significantly reduced the bacterial viability 24 hours after treatment for all substrates (P ≤0.05). The media pH significantly increased when samples were treated with CHX and BL+CHX (P ≤0.001). Confocal laser scanning microscopy images visually showed an abundant quantity of red cells in the samples treated with BL+CHX. There was no difference in the SBS between the treatments (P ≥0.932). CONCLUSIONS: The association between BL and CHX reduced S. mutans biofilm and its regrowth on an in vitro orthodontic model and did not influence the bonding strength between bracket and enamel.

Physiochemical and bactericidal activity evaluation: Silver-augmented 3D-printed scaffolds-An in vitro study.

HYPOTHESIS: Injuries requiring resection of tissue followed by autogenous bone transfer may be prone to infection by Staphylococcus aureus, impeding recovery and increasing medical costs. For critical sized defects, the common approach to reconstruction is a tissue transfer procedure but is subject to limitations (e.g., donor site morbidity, cost, operating time). Utilizing beta tricalcium phosphate (ß-TCP) as bone grafting material augmented with silver (Ag), a custom graft may be 3D printed to overcome limitations and minimize potential infections. EXPERIMENTS: Scaffolds were 3D printed and augmented with Ag by external attack on the surface by silver nitrate (AgNO3 ) at varying concentrations (0.1, 1.0, 10% wt/wt of scaffold). The augmented scaffolds were evaluated utilizing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and inductively coupled plasma mass spectroscopy (ICP-MS) to verify the presence of Ag and phosphate (PO4 ) groups followed by electron microscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) to gather information of chemical and physical properties. Preliminary biocompatibility and bactericidal capacity of the scaffolds were tested using human osteoprogenitor (hOP) cells and methicillin-sensitive S. aureus strain, respectively. RESULTS: XRD, FTIR, ICP-MS, TGA, and DSC confirmed presence of Ag and PO4 groups, whereas electron microscopy showed a decrease in Ca and an increase in Ag ions, decreasing Ca/P ratio with increasing surfactant concentrations. PrestoBlue assays yielded an increase in fluorescence cell counts among experimental groups with lower concentrations of Ag characterized by their characteristic trapezoidal shape whereas cytotoxicity was observed at higher concentrations. Similar observations were made with alkaline phosphatase assays. Antimicrobial evaluation showed reduced colony-forming units (CFU) among all experimental groups when compared to 100% ß-TCP. ß-TCP scaffolds augmented with Ag ions facilitate antibacterial effects while promoting osteoblast adhesion and proliferation.

In-vitro evaluation of the anti-cariogenic effect of a hybrid coating associated with encapsulated sodium fluoride and stannous chloride in nanoclays on enamel

Abstract Objective The aim of this study is to test, in vitro, the anti-cariogenic effect of experimental hybrid coatings, with nano clays of halloysite or bentonite, loaded with sodium fluoride or with a combination of sodium fluoride and stannous chloride, respectively. Methodology The varnish Fluor Protector (1,000 ppm of F-) was used as positive control and no treatment was the negative control. Enamel specimens (5 mm × 5 mm) were obtained from bovine teeth. The specimens (n=10) had their surfaces divided into two halves (5 mm × 2.5 mm each), in which one half received one of the treatments (Hybrid; Hybrid + NaF; Hybrid + NaF + SnCl2; Hybrid + NaF Loaded; Hybrid + NaF + SnCl2 Loaded). The specimens were submitted to a cariogenic challenge using a biofilm model (S. mutans UA159, for 5 days). Enamel surfaces both under and adjacent to the treated area were analyzed for mineral loss and lesion depth, by transverse microradiography. The pH of the medium was measured twice a day, and the fluoride release was analyzed. Additional specimens were submitted to confocal analysis. Results Data were statistically analyzed by two-way ANOVA followed by Tukey test (α=0.05). None of hybrid groups were able to reduce the lesion depth; the Hybrid + NaF group, however, was able to reduce mineral loss differing from the negative control (p=0.008). The groups showed no significant difference in the pH measurement and fluoride release. Confocal analysis confirmed that for all groups the biofilm growth was similar. Conclusion None of the hybrid groups reduced lesion depth, but the Hybrid + NaF group was able to promote protection against mineral loss.

Diaminomaleonitrile derivatives as new potential antichagasic compounds: a study of structure-activity relationships.

Background: Schiff bases are synthetically accessible compounds that have been used in medicinal chemistry. Methods & results: In this work, 27 Schiff bases derived from diaminomaleonitrile were synthesized in high yields (80-98%). Molecular docking studies suggested that the Schiff bases interact with the catalytic site of cruzain. The most active cruzain inhibitor, analog 13 (IC50 = 263 nM), was predicted to form an additional hydrophobic contact with Met68 in the binding site of the enzyme. A strong correlation between the IC50 values and ChemScore binding energies was observed (R = 0.99). Kernel-based 2D quantitative structure-activity relationship models for the whole dataset yielded sound correlation coefficients (R2 = 0.844; Q2 = 0.719). Conclusion: These novel and potent cruzain inhibitors are worthwhile starting points in further Chagas disease drug discovery programs.

Correction: Trans,trans-farnesol, an antimicrobial natural compound, improves glass ionomer cement properties.

[This corrects the article DOI: 10.1371/journal.pone.0220718.].

Candida biofilm matrix as a resistance mechanism against photodynamic therapy.

BACKGROUND: Antimicrobial photodynamic therapy (aPDT) efficiency on Candida albicans is recognized in free-floating cultures. Though, the lack of aPDT effectiveness against C. albicans organized in biofilms is still unclear. This study aimed to explore the role of the extracellular matrix (ECM) in the protection against aPDT in C. albicans biofilms. METHODS: C. albicans SN 425 wild-type and two mutant strains CNJ 2302; Δ/Δefg1 and CJN 2330; Δ/Δtec1 (ECM deficient) were used. Biofilms were grown on 24-well plates and exposed twice-daily to aPDT with 44 µM toluidine blue-O (TBO) for 5 min followed by red light (635 nm) for 1 min (87.6 J/cm²) or 2 min (175.2 J/cm2). Application of just TBO, light, 0.12% chlorhexidine, and ultrapure water were used as controls. After 48 h, biofilms were assessed for dry-weight (DW), colony forming units (CFU), extracellular DNA (eDNA), soluble and insoluble protein (SP/IP), water-insoluble (alkali-soluble) polysaccharide (ASP), water-soluble polysaccharides (WSP), and confocal scanning laser microscopy. RESULTS: The strains with ECM deficient were affected by aPDT. For the mutant strain Δ/Δefg1, aPDT significantly reduced CFU, ASP, DW, eDNA, WSP and IP when compared to NC (p<0.001) and for the Δ/Δtec1, aPDT significantly reduced CFU, eDNA, IP and SP. Whereas CFU, DW, ASP of the wild-type strain biofilms were not reduced (p>0.05). CONCLUSIONS: C. albicans strains with reduced ECM compounds were more sensitive to aPDT suggesting that the ECM may have a significant protection role from aPDT in C. albicans biofilms.

In vitro study on how cold plasma affects dentin surface characteristics.

PURPOSE: Studies evaluating different features of cold plasma action on dentin surface characteristics are lacking. Thus, this in vitro study aimed to determine the effect of cold plasma under different protocols of exposure time, distance to plasma source, and the association of argon gas with distinct concentrations of oxygen on the wettability, surface energy, total free interaction energy, surface roughness, morphology and chemical composition of dentin. MATERIAL AND METHODS: One hundred and twenty-five bovine dentin samples were used and divided into twenty-five groups according to the exposure time to plasma (15, 30, or 60 s); distance between plasma source and dentin surface (3 or 6 mm); argon gas without plasma generation; and plasma generated by argon gas and association of argon gas with distinct concentrations of oxygen (2 % or 3 %) (n = 5). Contact angle (θ), surface energy (γs) and total free interaction energy (ΔG) were measured using a goniometer (Krüss), while surface roughness (Ra) was evaluated by a profilometer (Mitutoyo). Representative samples were submitted to scanning electron microscopy (JEOL) to ilustrate the morphology and chemical composition of dentin. Data comparing control group with all experimental groups were submitted to ANOVA followed by Tukey's test (α = .05). Data comparing oxygen gas action at different concentrations and argon gas on dentin characteristics were submitted to non-parametric Kruskal-Wallis test, followed by Dunn test for comparison between the groups and methods (α = 0.05). RESULTS: In general, argon gas without plasma generation promoted no significant difference on dentin surface characteristics compared to control group (P > .05), differently for the cold plasma that significantly reduced contact angle values and increased total free interaction energy of dentin surface (P < .05). Overall, feeding of oxygen at distinct concentrations promoted significant difference on dentin surface characteristics compared to control group (P < .05). Exposure time and distance protocols interfered with contact angle, surface energy and total free interaction energy analyses for each gas. There was no significant difference on surface roughness (P > .05), morphology and chemical composition of dentin submitted to argon gas, cold plasma, and distinct concentrations of oxygen. CONCLUSION: In conclusion, plasma generated by argon gas and its feeding with 2 % and 3 % oxygen gas improved the dentin surface characteristics about wettability, surface energy and total free interaction energy. Such treatments preserved the surface roughness, morphology and chemical composition of dentin. The protocols of groups Ar-6mm-15sec, ArO2-3mm-30sec and ArO3-3mm-15sec are recommended for improvement of dentin surface characteristics.

Evaluation of the impact of pain from dental urgencies on the patients' oral health- related quality of life: a cross- sectional study

Background. This cross-sectional study aimed to evaluate the impact of pain from dental urgencies on the oral health-related quality of life (OHRQoL). Methods. A sample of sixty-eight patients seeking urgent attention to a primary health unit were included. Clinical diagnosis and sociodemographic data were assessed, dental pain measured by visual analog scale (VAS) and numerical pain rating scale (NPRS). The Oral Health Impact Profile-14 (OHIP-14) instrument was used to measure the OHRQoL. Associations were analyzed using the Student t-test, except for types of urgencies, that were evaluated with one-way analysis of variance (ANOVA) test. Results. The most prevalent urgency type was of endodontic origin (81%). There was no difference between pain and other variables. The type of tooth showed significant differences in OHIP-14 scores. Conclusion. Dental urgencies were associated with a high level of pain and impacted negatively on the patients' OHRQoL. The type of tooth had a positive association the OHRQoL measures.