Gallic acid triphenylphosphonium derivatives TPP+-C10 and TPP+-C12 inhibit mitochondrial function in Candida albicans exerting antifungal and antibiofilm effects.

AIMS: To evaluate the antifungal and antibiofilm activity of gallic acid derivatives TPP+-C10 and TPP+-C12 and their effects on mitochondrial function on two Candida albicans reference strains (ATCC 90029 and ATCC 10231). METHODS AND RESULTS: First, we determined minimal inhibitory concentration (MIC) using a microdilution assay. Both compounds exerted antifungal effects, and their MICs ranged from 3.9 to 13 µM, with no statistically significant differences between them (P > 0.05, t-test). These concentrations served as references for following assays. Subsequently, we measured oxygen consumption with a Clark electrode. Our observations revealed that both drugs inhibited oxygen consumption in both strains with TPP+-C12 exerting a more pronounced inhibitory effect. We then employed flow cytometry with TMRE as a probe to assess mitochondrial membrane potential. For each strain assayed, the compounds induced a decay in transmembrane potential by 75%-90% compared to the control condition (P < 0.05, ANOVA). Then, we measured ATP levels using a commercial kit. TPP+-C12 showed a 50% decrease of ATP content (P < 0.05 ANOVA), while TPP+-C10 exhibited a less pronounced effect. Finally, we assessed the antibiofilm effect using the MTT reduction assay. Both compounds were effective, but TPP+-C12 displayed a greater potency, requiring a lower concentration to inhibit 50% of biofilms viability (P < 0.05, t-test). CONCLUSIONS: Derivatives of gallic acid linked to a TPP+ group exert antifungal and antibiofilm activity through impairment of mitochondrial function in C. albicans.

Kaempferol Induces Cell Death and Sensitizes Human Head and Neck Squamous Cell Carcinoma Cell Lines to Cisplatin.

Cisplatin is a first-line chemotherapeutic drug commonly used to treat patients with head and neck cancer; nevertheless, cisplatin resistance poses a main challenge for its clinical efficacy. Recent studies have shown that kaempferol, a natural flavonoid found in various plants and foods, has an anticancer effect. The following study evaluated the cytotoxic effects of kaempferol on head and neck tumor cells and their mechanism of action, evaluating the effects on proliferation, the oxygen consumption rate, transmembrane potential, tumor cell migration and induction of apoptosis. Moreover, we determined the effects of a combination of kaempferol and cisplatin on head and neck tumor cells. We found that kaempferol inhibited the oxygen consumption rate and decreased the intracellular ATP content in tumor cells. This novel mechanism may inhibit the migratory capacity and promote antiproliferative effects and apoptosis of tumor cells. Additionally, our in vitro data indicated that kaempferol may sensitize head and neck tumor cells to the effects of cisplatin. These effects provide new evidence for the use of a combination of kaempferol and cisplatin in vivo and their future applications in head and neck cancer therapy.

The consumption of milk supplemented with probiotics decreases the occurrence of caries and the salivary concentration of hßD-3 in children.

OBJECTIVES: This study evaluated the effect of milk supplemented with Lactobacillus rhamnosus SP1 on the occurrence of caries and the salivary concentration of human ß-defensin-3 (hßD-3) in preschool children with high caries risk. MATERIALS AND METHODS: A sample of 42 children was randomly assigned to two groups; children in the intervention group were given 150 mL of milk supplemented with 107 CFU/mL of Lactobacillus rhamnosus SP1, while children in the control group were given standard milk, for 10 months. The occurrence of dental caries was assessed using the International Caries Detection and Assessment System (ICDAS), and the concentration of hßD-3 was measured in unstimulated saliva using an ELISA test at baseline and after the intervention. RESULTS: There was an increase in the number of teeth with carious lesions (dICDAS2-6 mft) in the control group, and this increase was statistically significant (p = 0.0489). The concentration of hßD-3 in saliva from the intervention group decreased from 597.91 to 126.29 pg/mL (p = 0.0061), unlike in the control group, where no change in hßD-3 salivary concentration was found. CONCLUSIONS: These findings showed that regular intake of probiotic-supplemented milk in preschool children with high caries risk decreased the occurrence of caries and the salivary levels of hßD-3. CLINICAL RELEVANCE: Our results suggest the need for developing and implementing probiotic supplementation, as adjuvants to the conventional treatments for caries and allow to considerate the salivary levels of hßD-3 as markers of oral tissue homeostasis.

Chemical Characterization of Lavandula dentata Essential Oil Cultivated in Chile and Its Antibiofilm Effect against Candida albicans.

Candida albicans is the most common human fungal pathogen, and with the increase in resistance rates worldwide, it is necessary to search for new pharmacological alternatives. Lavandula dentata L. essential oil is recognized as having antimicrobial properties. However, its effect against fungal biofilms has been poorly described. C. albicans-related infections involve the development of biofilms, which are highly resistant to conventional antifungals. In this work, we evaluated the antibiofilm effect of L. dentata L. essential oil against C. albicans. First, we characterized the essential oil by gas chromatography-mass spectrometry. The antifungal effect on C. albicans reference strains was evaluated by a disk diffusion assay and the minimal inhibitory concentration was obtained through a microdilution assay. The effect of the essential oil on the adhesion ability of C. albicans was determined through a crystal violet assay, and morphogenesis inhibition was assessed by light microscopy. The effect of the essential oil on the microarchitecture of biofilms was evaluated through scanning electron microscopy. Finally, the antibiofilm effect was evaluated through an adapted biofilm scratch assay and XTT viability assay. The main constituent of the essential oil was the monoterpenoid eucalyptol (60%). The essential oil presented minimal inhibitory concentrations of 156 and 130 µg/mL against two strains assayed. This minimal inhibitory concentration inhibited adhesion, morphogenesis, biofilm formation, altered microarchitecture, and decreased the viability of established biofilms formed on abiotic surfaces for both strains assayed. This study demonstrates that the essential oil from L. dentata could be a promising treatment against C. albicans biofilms.

Nanoencapsulation of Maqui (Aristotelia chilensis) Extract in Chitosan-Tripolyphosphate and Chenopodin-Based Systems.

Maqui berries contain a high percentage of anthocyanins with high antioxidant and anti-inflammatory capacity but that are unstable in the colonic site. Nanocarriers based on polysaccharides and/or proteins can protect against the degradation of anthocyanins. The aim of this study was the nanoencapsulation of maqui extract (ME) in chitosan-tripolyphosphate (CTPP-ME), chenopodin (CH-ME), and chenopodin-alginate (CHA-ME). A standardised ME was prepared and then encapsulated in the nanosystems. The physicochemical properties, encapsulation parameters, and the interactions of ME with the nanovehicles were characterised. The cyanidin-3-glucoside released and ORAC activity in phosphate buffer at pH 7.4 were evaluated. The content of ME was 8-9 mg of cyanidin-3-glucoside/g of extract. CTPP with ME at 3% obtained the highest encapsulation efficiency (EE = 91%), and no significant differences were observed in size (274-362 nm), PDI (0.5-0.7), and zeta potential (+34-+41 mV) when the concentration of ME changed from 1% to 5%. CH-ME was shown to be smaller (152 nm) than CTPP-ME, and CH-ME and CHA-ME showed lower EE (79% and 54%, respectively) than CTPP-ME. FT-IR revealed a stronger interaction of ME with CTPP-ME than with CH-ME. Both systems showed a significantly lower release than free ME, and the T50 value of CTPP-ME 3% (328 min) was higher than CH-ME (197 min). Both protected the ORAC activity of ME.

Worldwide Variations in Fluoride Content in Beverages for Infants.

In situations where breastfeeding is impractical, milk formulas have emerged as the primary choice for infant nutrition. Numerous global studies have scrutinized the fluoride content in these formulas, uncovering fluctuations in fluoride levels directly associated with the method of preparation. This variability poses a potential risk of elevated fluoride concentrations and, consequently, an increased susceptibility to dental fluorosis in infants. The primary objective of this review is to intricately delineate the fluoride content in dairy formulas and emphasize the variability of these values concerning their reconstitution process. The review's findings reveal that, among the 17 studies assessing fluoride levels in infant formula, milk-based formulas exhibit a range of 0.01-0.92 ppm, with only two studies exceeding 1.30 ppm. Conversely, soy-based formulas demonstrate values ranging from 0.13-1.11 ppm. In conclusion, the observed variability in fluoride levels in infant formulas is ascribed to the choice of the water source employed in the preparation process. This underscores the paramount importance of meticulously adhering to recommendations and guidelines provided by healthcare professionals concerning the utilization of these formulas and their meticulous reconstitution.

Origanum vulgare L. essential oil inhibits virulence patterns of Candida spp. and potentiates the effects of fluconazole and nystatin in vitro.

BACKGROUND: Recurrence and resistance of Candida spp. infections is associated with the ability of these microorganisms to present several virulence patterns such as morphogenesis, adhesion, and biofilm formation. In the search for agents with antivirulence activity, essential oils could represent a strategy to act against biofilms and to potentiate antifungal drugs. OBJECTIVE: To evaluate the antivirulence effect of Origanum vulgare L. essential oil (O-EO) against Candida spp. and to potentiate the effect of fluconazole and nystatin. METHODS: The effect of O-EO was evaluated on ATCC reference strains of C. albicans and non-albicans Candida species. Minimum inhibitory concentration (MIC) was determined through broth microdilution assay. Adhesion to microplates was determined by crystal violet (CV) assay. An adapted scratch assay in 24-well was used to determine the effect of essential oil on biofilms proliferation. Viability of biofilms was evaluated by MTT reduction assay and through a checkerboard assay we determined if O-EO could act synergistically with fluconazole and nystatin. RESULTS: MIC for C. albicans ATCC-90029 and ATCC-10231 was 0.01 mg/L and 0.97 mg/L, respectively. For non-albicans Candida strains MIC values were 2.6 mg/L for C. dubliniensis ATCC-CD36 and 5.3 mg/L for C. krusei ATCC-6258. By using these concentrations, O-EO inhibited morphogenesis, adhesion, and proliferation at least by 50% for the strains assayed. In formed biofilms O-EO decreased viability in ATCC 90029 and ATCC 10231 strains (IC50 7.4 and 2.8 mg/L respectively). Finally, we show that O-EO interacted synergistically with fluconazole and nystatin. CONCLUSIONS: This study demonstrate that O-EO could be considered to improve the antifungal treatment against Candida spp.

Li-doped bioglass® 45S5 for potential treatment of prevalent oral diseases.

OBJECTIVES: Despite the excellent properties of both pure bioglasses (BG) and BG doped with therapeutic ions (such as Li) in hard tissue applications, there is not enough information about their role in the remineralization and bacterial-growth in oral diseases. The aim of this contribution is to evaluate the effect of both pure BG and BG doped with 5-wt% of Li (BGLi) on both the remineralization of in vitro demineralized human-teeth and the antimicrobial behavior against strains from caries and periodontitis. METHODS: Bioglass® 45S5 (BG) and BGLi were synthesized by the sol-gel method. The remineralization tests were carried out using in vitro demineralized enamel teeth and evaluated by Electron Microscopy (SEM) and Vickers micro-hardness (HV). The antimicrobial behavior of the particles was evaluated against S. mutans, A. actinomycetemcomitans, and P. gingivalis, representing pathogens from caries and periodontitis. RESULTS: Enamel lesion was partially remineralized when both bioglasses (BG and BGLi) were applied on its surface with micro-hardness recoveries around 45 %. They further inhibited the growth of S. mutans and P. gingivalis, at 50 and 200 mg/mL, respectively. BGLi presented a higher toxicity against A. actinomycetemcomitans than BG, with inhibition concentrations of 20 mg/mL and 100 mg/mL, respectively. CONCLUSIONS: Bioglasses could be used in the treatment of two of the most prevalent oral diseases: caries and periodontitis, promoting the remineralization of the teeth and killing the main pathogens. The presence of Li did not affect the bioactivity of the bioglass and improved the antibacterial effect over A. actinomycetemcomitans strain.

The effect of chitosan as internal or external coating on the 5-ASA release from calcium alginate microparticles.

The effect of chitosan as internal or external coating on the mesalamine (5-ASA) release from calcium alginate microparticles (CaAl) was studied, and a delayed release of 5-ASA system intended for colonic drug delivery was developed. The external chitosan coating was developed by immersion of wetted CaAl in chitosan solution and the internal coating by mixing 5-ASA with chitosan solution and drying before the preparation of CaAl. Both systems were coated with Acryl-EZE® using combined fluid bed coating and immersion procedure. The results showed that in phosphate medium (pH 7.5), chitosan as 5-ASA coating promotes a quick erosion process accelerating drug release, but chitosan as external coating (CaAlCS) does not increase the T (50) value compared with the microparticles without chitosan (CaAl). Chitosan as internal or external coating was not effective to avoid the quick 5-ASA release in acidic medium (pH 1.2). The presence of ß-glucosidase enzymes increases significantly the 5-ASA release for CaAl, while no effect was observed with chitosan as internal or external coating. Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray data revealed that 5-ASA did not form a solid solution but was dispersed in the microparticles. The Acryl-EZE® coating of microparticles was effective because all the formulations showed a low release, less than 15%, of 5-ASA in acid medium at pH 1.2. Significant differences in the percentage of 5-ASA released between formulations were observed in phosphate buffer at pH 6.0. In phosphate buffer at pH 7.2, all the formulations released 100% of 5-ASA.

Selective crystallization of calcium salts by poly(acrylate)-grafted chitosan.

The biopolymer chitosan was chemically modified by grafting polyacrylamide or polyacrylic acid in a homogeneous aqueous phase using potassium persulfate (KPS) as redox initiator system in the presence of N,N-methylene-bis-acrylamide as a crosslinking agent. The influence of the grafted chitosan on calcium salts crystallization in vitro was studied using the sitting-drop method. By using polyacrylamide grafted chitosan as substrate, rosette-like CaSO4 crystals were observed. This was originated by the presence of sulfate coming from the initiator KPS. By comparing crystallization on pure chitosan and on grafted chitosan, a dramatic influence of the grafted polymer on the crystalline habit of both salts was observed. Substrates prepared by combining sulfate with chitosan or sulfate with polyacrylamide did not produce similar CaSO4 morphologies. Moreover, small spheres or donut-shaped CaCO3 crystals on polyacrylic acid grafted chitosan were generated. The particular morphology of CaCO3 crystals depends also on other synthetic parameters such as the molecular weight of the chitosan sample and the KPS concentration.

Synthesis of nanostructured porous silica coatings on titanium and their cell adhesive and osteogenic differentiation properties.

Nanostructured porous silica coatings were synthesized on titanium by the combined sol-gel and evaporation-induced self-assembly process. The silica-coating structures were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and nitrogen sorptometry. The effect of the nanoporous surface on apatite formation in simulated body fluid, protein adsorption, osteoblast cell adhesion behavior, and osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) is reported. Silica coatings with highly ordered sub-10 nm porosity accelerate early osteoblast adhesive response, a favorable cell response that is attributed to an indirect effect due to the high protein adsorption observed on the large-specific surface area of the nanoporous coating but is also probably due to direct mechanical stimulus from the nanostructured topography. The nanoporous silica coatings, particularly those doped with calcium and phosphate, also promote the osteogenic differentiation of hBMSCs with spontaneous mineral nodule formation in basal conditions. The bioactive surface properties exhibited by the nanostructured porous silica coatings make these materials a promising alternative to improve the osseointegration properties of titanium dental implants and could have future impact on the nanoscale design of implant surfaces.

Designing antimicrobial bioactive glass materials with embedded metal ions synthesized by the sol-gel method.

Bioactive glasses (SiO2-P2O5-CaO) having tailored concentrations of different biocide metal ions (copper or silver) were produced by the sol-gel method. All the particles release phosphorous ions when immersed in water and simulated body fluid (SBF). Moreover, a surface layer of polycrystalline hydroxy-carbonate apatite was formed on the particle surfaces after 10 day immersion in SBF as confirmed by X-ray diffraction and scanning electron microscopy (SEM) showing the bioactive materials. Samples with embedded either copper or silver ions were able to further release the biocide ions with a release rate that depends on the metal embedded and the dissolution medium: water or SBF. This biocide ion release from the samples explains the antimicrobial effect of our active particles against Escherichia coli DH5α ampicillin-resistant (Gram-negative) and Streptococcus mutans (Gram-positive) as determined by the Minimum Bactericidal Concentration (MBC) method. The antimicrobial behavior of the particles depends on the bacteria and the biocide ion used. Noteworthy, although samples with copper are able to release more metal ion than samples with silver, they present higher MBC showing the high effect of silver against these bacteria.

Creación de un Currículo de Competencias en Cariología para Estudiantes de Pregrado de Odontología en Chile / Development of a Competency-based Curriculum in Cariology for Undergraduate Dental Students in Chile

RESUMEN: Objetivo: Creación de un currículo de competencias mínimas en Cariología, para la formación de los Cirujano-Dentistas egresados de las escuelas de Odontología de Chile. Metodologías: A partir de una reunión de académicos de las Universidades de Talca y de Chile (año 2011), se elaboró una propuesta de currículo inicial, basado en los dominios propuestos por la Unión Europea (Schulte AG y cols). Durante el año 2016, dicha propuesta fue analizada mediante diálogos digitales y grupos de trabajo, con la participación del 96% de las Escuelas de Odontología existentes en el país, que concluyeron en un documento intermedio. Este documento fue analizado, discutido y perfeccionado durante el Taller para el Desarrollo de un Currículo de Competencias Mínimas en Cariología para las Escuelas de Odontología Chilenas (22/Mayo/2017, Talca, organizado por la Universidad de Talca y la Universidad de Chile) con la asistencia de representantes del 96% de las escuelas dentales chilenas, Ministerio de Salud de Chile, Colegio de Cirujano-Dentistas de Chile y con la asesoría de los profesores de Cariología Dres. Margherita Fontana y Carlos González-Cabezas (Universidad de Michigan, Ann Arbor, EEUU). Cada grupo de trabajo revisó el documento y envió nuevos comentarios, los que fueron incorporados en el documento final por una comisión asesora. Resultados: El documento del Currículo en Cariología se organizó en 5 Dominios: 1. Conocimientos base; 2. Determinación de Riesgo, diagnóstico de caries y detección de lesiones de caries; 3. Toma de decisiones y manejo preventivo no operatorio; 4. Toma de decisiones y manejo operatorio y 5. Cariología basada en la evidencia, en la práctica clínica y de salud pública. Se consensuaron las definiciones operacionales, las competencias principales y las sub-competencias para cada uno de los dominios. Las sub-competencias fueron clasificadas en tres niveles: A: Ser competente en; B: Tener conocimientos sobre y C: Estar familiarizado con. El documento final fue enviado a todos los participantes del taller para su aprobación y difusión en cada una de las instituciones involucradas. Conclusiones: Se logró, por medio de consenso, la construcción del Currículo de Competencias mínimas en Cariología para estudiantes de pregrado de Odontología en las universidades chilenas.

ABSTRACT: Objective: Development of a minimum set of competencies in Cariology that every dentist graduated from a Dental School in Chile must have. Methodology: Starting from a meeting of scholars from the Universities of Talca and Chile (year 2011), an initial proposal for a curriculum was developed, based on the domains proposed by the European Cariology Curriculum (Schulte, et al, 2011). During 2016, this proposal was discussed through online dialogues and working groups, with the participation of 95.2% of the Chilean dental schools, which resulted in an intermediate document. This document was analyzed, discussed and refined during the Workshop for the Development of a Curriculum of Minimum Competencies in Cariology for Chilean Dental Schools (May 22, 2017, Talca, organized by the Universities of Talca and Chile) with the attendance of representatives from 95.2% of the Chilean dental schools, the Chilean Ministry of Health, Chilean College od Dentists and with the assistance of the professors of Cariology Margherita Fontana and Carlos González-Cabezas (University of Michigan, Ann Arbor, USA). Each working group revised the document and provided feedback, which was incorporated in the final document by an advisory committee, elected on the day of the workshop, including the authors of the present article. Results: The Cariology Curriculum was organized in 5 Domains: 1. Basic knowledge; 2. Risk assessment, caries diagnosis and caries lesion detection; 3. Decision-making and non-operative preventive treatment; 4. Decision making and operative treatment; and 5. Evidence-based, clinical and public health practice. Operational definitions, main competencies and sub-competencies for each domain were agreed. Sub-competencies were classified into three levels: A: Be competent in; B: Have knowledge about, and C: Be familiar with. The final document was sent to all the participants of the workshop for dissemination in each of the institutions involved. Conclusions: The development of the Competency-based Curriculum in Cariology for undergraduate dental students at Chilean universities was achieved through consensus.

Preparation and bioactive properties of novel bone-repair bionanocomposites based on hydroxyapatite and bioactive glass nanoparticles.

Bionanocomposites based on ceramic nanoparticles and a biodegradable porous matrix represent a promising strategy for bone repair applications. The preparation and bioactive properties of bionanocomposites based on hydroxyapatite (nHA) and bioactive glass (nBG) nanoparticles were presented. nHA and nBG were synthesized with nanometric particle size using sol-gel/precipitation methods. Composite scaffolds were prepared by incorporating nHA and nBG into a porous alginate (ALG) matrix at different particle loads. The ability of the bionanocomposites to induce the crystallization of the apatite phase from simulated body fluid (SBF) was systematically evaluated using X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray analysis, and Fourier transform infrared spectroscopy. Both nHA/ALG and nBG/ALG composites were shown to notably accelerate the process of crystallization and growth of the apatite phase on the scaffold surfaces. For short immersion times in SBF, nBG (25%)-based nanocomposites induced a higher degree of apatite crystallization than nHA (25%)-based nanocomposites, probably due to the more reactive nature of the BG particles. Through a reinforcement effect, the nanoparticles also improve the mechanical properties and stability in SBF of the polymer scaffold matrix. In addition, in vitro biocompatibility tests demonstrated that osteoblast cells are viable and adhere well on the surface of the bionanocomposites. These results indicate that nHA- and nBG-based bionanocomposites present potential properties for bone repair applications, particularly oriented to accelerate the bone mineralization process.