Effect of treatment time on performance of nano-encapsulated fluoride dentifrices for remineralization of initial carious lesions: an in vitro study.

The aim of this in vitro study was to evaluate the influence of treatment time on the remineralization performance of nanoencapsulated fluoride dentifrices on initial carious lesions. Ninety-six human enamel samples were allocated to eight groups (n = 12): 50% NanoF + 50% free NaF, 100% NanoF, 100% NaF (positive control), and placebo (negative control), using two different treatment times (one and five minutes) for each dentifrice tested. After the carious lesion induction, the specimens were submitted to a pH remineralizing cycling model for seven days. Surface microhardness was measured before and after carious lesion induction and after treatment. The percentage of surface remineralization was calculated for each study time. Data were analyzed using two-way ANOVA and ANOVA repeated-measures tests followed by the Bonferroni correction (p < 0.05). Remineralization differences were observed in the dentifrices analyzed according to the treatment time used. NanoF formulations with 50% (one-min treatment) and 100% (five-min treatment) promoted significant remineralization of enamel after the caries challenge when compared to the placebo dentifrice (p < 0.05). Thus, time was considered an important factor for the fluoride release system. Nanotechnology can be a promising system for caries remineralization as it makes fluoride available on the dental surface for a longer time.

O objetivo deste estudo in vitro foi de avaliar a influência do tempo de tratamento no desempenho de dentifrícios fluoretados nano-encapsulados na remineralização de lesões cariosas iniciais. Noventa e seis amostras de esmalte humano foram divididas em oito grupos (n = 12): 50% NanoF + 50% NaF livre, 100% NanoF, 100% NaF (controle positivo) e Placebo (controle negativo) com dois tempos diferentes (um e cinco minutos). Após a indução da lesão cariosa, os espécimes foram submetidos a um modelo de ciclagem de pH por sete dias. A microdureza superficial foi medida antes e após a indução da lesão cariosa e após o tratamento. O percentual de remineralização superficial foi calculado para cada tempo de estudo. Os dados foram analisados pelo ANOVA e ANOVA de medidas repetidas, seguida de Bonferroni (p <0,05). Diferenças de remineralização foram observadas nos dentifrícios de acordo com o tempo de tratamento utilizado. Formulações NanoF com 50% (tratamento de um minuto) e 100% (tratamento de cinco minutos) promoveram uma remineralização do esmalte, após o desafio cariogênico, quando comparado com o dentifrício placebo (p <0,05). Assim, o tempo foi considerado um fator importante para o sistema de liberação de flúor. A nanotecnologia pode ser um sistema promissor de remineralização da cárie, por disponibilizar o flúor por maior tempo na superfície dentária.

Effect of treatment time on performance of nano-encapsulated fluoride dentifrices for remineralization of initial carious lesions: an in vitro study / Efeito do tempo de tratamento no desempenho de dentifrícios de fluoreto nanoencapsulado para remineralização de lesões iniciais de cárie: um estudo in vitro

ABSTRACT The aim of this in vitro study was to evaluate the influence of treatment time on the remineralization performance of nanoencapsulated fluoride dentifrices on initial carious lesions. Ninety-six human enamel samples were allocated to eight groups (n = 12): 50% NanoF + 50% free NaF, 100% NanoF, 100% NaF (positive control), and placebo (negative control), using two different treatment times (one and five minutes) for each dentifrice tested. After the carious lesion induction, the specimens were submitted to a pH remineralizing cycling model for seven days. Surface microhardness was measured before and after carious lesion induction and after treatment. The percentage of surface remineralization was calculated for each study time. Data were analyzed using two-way ANOVA and ANOVA repeated-measures tests followed by the Bonferroni correction (p < 0.05). Remineralization differences were observed in the dentifrices analyzed according to the treatment time used. NanoF formulations with 50% (one-min treatment) and 100% (five-min treatment) promoted significant remineralization of enamel after the caries challenge when compared to the placebo dentifrice (p < 0.05). Thus, time was considered an important factor for the fluoride release system. Nanotechnology can be a promising system for caries remineralization as it makes fluoride available on the dental surface for a longer time.

RESUMO O objetivo deste estudo in vitro foi de avaliar a influencia do tempo de tratamento no desempenho de dentifrícios fluoretados nano-encapsulados na remineralizagao de lesoes cariosas iniciáis. Noventa e seis amostras de esmalte humano foram divididas em oito grupos (n = 12): 50% NanoF + 50% NaF livre, 100% NanoF, 100% NaF (controle positivo) e Placebo (controle negativo) com dois tempos diferentes (um e cinco minutos). Após a indugao da lesao cariosa, os espécimes foram submetidos a um modelo de ciclagem de pH por sete dias. A microdureza superficial foi medida antes e após a indugao da lesao cariosa e após o tratamento. O percentual de remineralizagao superficial foi calculado para cada tempo de estudo. Os dados foram analisados pelo ANOVA e ANOVA de medidas repetidas, seguida de Bonferroni (p <0,05). Diferengas de remineralizagao foram observadas nos dentifrícios de acordo com o tempo de tratamento utilizado. Formulagoes NanoF com 50% (tratamento de um minuto) e 100% (tratamento de cinco minutos) promoveram uma remineralizagao do esmalte, após o desafio cariogènico, quando comparado com o dentifricio placebo (p <0,05). Assim, o tempo foi considerado um fator importante para o sistema de liberagao de flúor. A nanotecnologia pode ser um sistema promissor de remineralizagao da cárie, por disponibilizar o flúor por maior tempo na superficie dentària.

Potential antibacterial and anti-halitosis activity of medicinal plants against oral bacteria.

This study aimed to evaluate the in vitro activity of the crude extracts obtained from Caesalpinia ferrea Mart. (Jucá), Cinnamomum cassia B. (Cinnamon), Mallow sylvestris L. (Mallow), Punica granatum L. (Pomegranate), Rosmarinus officinalis L. (Rosemary), Aeolanthus suaveolens (Als.) Spreng. (Macassá), Sysygium aromaticum L. (Clove), and Tamarindus indica L. (Tamarind) against oral microorganisms (e.g., Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, and Parvimonas micra) that produce volatile sulfur compounds (VSC). The pure extracts were placed in culture medium for the diffusion test in agar. The Minimum Inhibitory Concentration (MIC) was determined by the microdilution method, and microbial growth was assayed with resazurin. Total polyphenols in the extracts were measured by using the Prussian Blue Method. For the salivary sediment test, the sediments were exposed to the Jucá and Pomegranate extracts, which was followed by incubation and organoleptic measurements with a monitor (Halimeter®) at 1-, 2-, 4-, and 24 -h intervals. The diffusion test revealed mixed results for the extracts. When the zone of inhibition was present, it ranged from 1.6-10.3 mm. The Pomegranate extract was the only extract that inhibited all the evaluated microorganisms; the MIC values ranged from 50 to 400 µg/mL. The Pomegranate and Jucá extracts presented higher levels of polyphenols, 7.3 % and 3.9 %, respectively, and less VSC formation as compared to the negative control. In conclusion, the extracts display antimicrobial activity against the tested microorganisms. The investigated plants have the potential to reduce the main substances related to halitosis of oral origin.

In vitro leishmanicidal, antibacterial and antitumour potential of anhydrocochlioquinone A obtained from the fungus Cochliobolus sp.

The bioassay-guided fractionation of the ethyl acetate extract of the fungus Cochliobolus sp. highlighted leishmanicidal activity and allowed for anhydrocochlioquinone A (ANDC-A) isolation. MS, 1D and 2D NMR spectra of this compound were in agreement with those published in the literature. ANDC-A exhibited leishmanicidal activity with EC 50 value of 22.4 microgram/mL (44 mu M) and, when submitted to the microdilution assay against Gram-ositive and Gram-negative bacteria, showed a minimal inhibitory concentration against Staphylococcus aureus ATCC 25295 of 128 microgram/mL (248.7 mu M). It was also active against five human cancer cell lines, showing IC50 values from 5.4 to 20.3 mu M. ANDC-A demonstrated a differential selectivity for HL-60 (SI 5.5) and THP-1 (SI 4.3) cell lines in comparison with Vero cells and was more selective than cisplatin and doxorubicin against MCF-7 cell line in comparison with human peripheral blood mononuclear cells. ANDC-A was able to eradicate clonogenic tumour cells at concentrations of 20 and 50 mu M and induced apoptosis in all tumour cell lines at 20 mu M. These results suggest that ANDC-A might be used as a biochemical tool in the study of tumour cells biochemistry as well as an anticancer agent with durable effects on tumours.

AgNPs: The New Allies Against S. Mutans Biofilm - A Pilot Clinical Trial and Microbiological Assay.

The purpose of this study was to evaluate the antimicrobial properties of a new formulation containing silver nanoparticles, named Nano Silver Fluoride (NSF), to inhibit Streptococcus mutans biofilm formation on children's dental enamel. The variations in dental biofilm pH and in the Simplified-Oral-Hygiene-Index (OHI-S) also were evaluated after the treatment with NSF. This was a randomized, double-blind, crossover and prospective pilot clinical trial study in which 12 schoolchildren, aged between 7-8 years, had their dental enamel treated with two solutions: S1 - Nano Silver Fluoride and S2 - negative control (saline solution), in different experimental moments. The dental biofilm adhered to enamel treated with NSF had lower values of S. mutans viability (absorbance) and colony forming units (CFU) than the S0 (baseline) and S2. There was a statistically significant difference between the OHI-S mean values of S0 and S1. There were no differences between the biofilm pH (both before and after the use of the test substances) and among the different groups. These properties suggest that NSF has bactericidal effect against S. mutans biofilm and it may be used for clinical control and prevention of dental biofilm formation.

AgNPs: The New Allies Against S. Mutans Biofilm - A Pilot Clinical Trial and Microbiological Assay

Abstract: The purpose of this study was to evaluate the antimicrobial properties of a new formulation containing silver nanoparticles, named Nano Silver Fluoride (NSF), to inhibit Streptococcus mutans biofilm formation on children's dental enamel. The variations in dental biofilm pH and in the Simplified-Oral-Hygiene-Index (OHI-S) also were evaluated after the treatment with NSF. This was a randomized, double-blind, crossover and prospective pilot clinical trial study in which 12 schoolchildren, aged between 7-8 years, had their dental enamel treated with two solutions: S1 - Nano Silver Fluoride and S2 - negative control (saline solution), in different experimental moments. The dental biofilm adhered to enamel treated with NSF had lower values of S. mutans viability (absorbance) and colony forming units (CFU) than the S0 (baseline) and S2. There was a statistically significant difference between the OHI-S mean values of S0 and S1. There were no differences between the biofilm pH (both before and after the use of the test substances) and among the different groups. These properties suggest that NSF has bactericidal effect against S. mutans biofilm and it may be used for clinical control and prevention of dental biofilm formation.

Resumo O objetivo do presente estudo foi avaliar as propriedades antimicrobianas de uma nova formulação composta por nanopartículas de prata, denominada nano silver fluoride (NSF), na inibição de biofilme de Streptococcus mutans sobre a superfície do esmalte dentário de crianças. Variações no pH do biofilme dental e nos valores do índice de Higiene Oral Simplificada (IHO-S) também foram avaliadas após o tratamento com NSF. Trata-se de um estudo piloto, randomizado, duplo cego, cruzado e prospectivo. A amostra foi composta por 12 crianças, de ambos os gêneros, com idades entre 7 e 8 anos, as quais utilizaram as duas soluções testes, S1- NSF e S2- controle negativo (solução salina). O biofilme dental tratado com NSF apresentou menores valores de viabilidade de S. mutans (absorbância) e de unidades formadoras de colônias (UFC) do que o biofilme baseline e o biofilme tratado com S2. Houve diferença estatisticamente significativa entre os valores médios de IHO-S dos grupos baseline e S1, com uma redução dos valores. Não houve qualquer variação nos valores de pH do biofilme dental, antes e depois do tratamento com S1 e S2 e entre os diferentes grupos. Estas propriedades sugerem que NSF possui efeito bactericida sobre o biofilme de S. mutans, podendo ser utilizado clinicamente para o controle e prevenção da formação do biofilme dentário.

Antimicrobial and cytotoxicity evaluation of colloidal chitosan - silver nanoparticles - fluoride nanocomposites.

The present study aimed to evaluate the antimicrobial activity and cytotoxicity of colloidal chitosan - silver nanoparticle - fluoride nanocomposites (CChAgNpFNc), with different silver nanoparticle shapes and sizes. The syntheses of CChAgNpFNc were performed with silver nitrate added to a chitosan solution, addition of a sodium borohydride solution and solid sodium fluoride. Solution of ascorbic acid was added to synthesize larger silver nanoparticles. CChAgNpFNc obtained: S1- 100% spherical, 8.7±3.1nm; S2- 97% spherical, 15.0±7.9nm and 2.5% triangular, 22.2±9.5nm; S3- 77.3% spherical, 31.8±10.4nm, 15.9% triangular, 27.1±10.1nm and 6.8% elliptical, 33.2±7.8nm; and S4- 75.2% spherical, 43.2±14.3nm; 23.3% triangular 38.2±14.8nm, and 1.5% elliptical 38.4±11.6nm. The CChAgNpFNc showed antimicrobial activity against Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa and Candida albicans, by microdilution technique. The influence on the growth of microorganisms was evaluated using a fluorescence assay, and showed an increasing lag phase and a decreasing log phase. Cytotoxicity was investigated using Artemia salina and MTT assays. The S3 and S4 samples exhibited low cytotoxicity. The S1 and S2 samples inhibited murine macrophages and revealed lethal dose concentrations above 1000mg/mL that were classified as moderately toxic. Thus, CChAgNpFNc are potential options for the control of multiple-drug-resistant microorganisms and do not represent substantial risks to human health.

Dentin Cleaning Ability of an Amazon Bioactive: Evaluation by Scanning Electron Microscopy.

UNLABELLED: The role of dentin cleaning is to remove debris that may impair adaptation and marginal sealing, quantitatively reducing microorganisms. The aim of this study was to investigate through scanning electron microscopy (SEM) the morphology of the dentin surface, cut and treated with copaiba oil emulsions (CO) and suspension of ethanol extract of propolis (EP). Twenty four upper pre-molars teeth, divided into eight groups (n=3), were used: G1: no cleaning, G2: air/water spray, G3: 10% CO, G4: 10% CO + A, G5: 30% CO, G6: 30% CO + A, G7: 1% EP, G8: 2% Chlorhexidine. The specimens were dentin discs (1 mm Ø). The SEM photomicrographs were classified and the results were: G1 - Debris dentin on the entire image / countless microorganisms, G2 and G7 - 50-100 debris / countless microorganisms and G3, G4, G5, G6 and G8 - 0-50 debris / countable microorganisms (50-100 colonies). CONCLUSION: The present results suggest that copaiba oil emulsions (CO) and suspension of ethanol extract of propolis (EP) have feasibility to be used as bioactive dental cleaning agents.

In vitro antimicrobial activity of solution blow spun poly(lactic acid)/polyvinylpyrrolidone nanofibers loaded with Copaiba (Copaifera sp.) oil.

In this study poly(lactic acid) (PLA) and polyvinylpyrrolidone (PVP) micro- and nanofiber mats loaded with Copaiba (Copaifera sp.) oil were produced by solution blow spinning (SBS). The Copaiba (Copaifera sp.) oil was characterized by gas chromatography (GC). Neat PLA and four PLA/PVP blends containing 20% (wt.%) oil were spun and characterized by scanning electron microscopy (SEM) and by studying the surface contact angle, in vitro release rate, and antimicrobial activity. All compositions evaluated were able to produce continuous and smooth fibers by SBS. The addition of PVP increased fiber diameter, and decreased the surface contact angle. GC analysis demonstrated that the main component of the Copaiba oil was ß-caryophyllene, a known antimicrobial agent. In vitro release tests of Copaiba oil volatiles demonstrated a higher release rate in fibers containing PVP. Fiber mats made from blends containing higher amounts of PVP had greater antimicrobial action against Staphylococcus aureus. The results confirm the potential of the fiber mats for use in controlled drug release and could lead to promising applications in the biomedical field.

Action of silver nanoparticles towards biological systems: cytotoxicity evaluation using hen's egg test and inhibition of Streptococcus mutans biofilm formation.

This study aimed to evaluate the cytotoxicity and bactericidal properties of four silver nanoparticle (AgNP) colloids and their ability to inhibit Streptococcus mutans biofilm formation on dental enamel. The cytotoxicity of AgNPs was evaluated based on signs of vascular change on the chorioallantoic membrane using the hen's egg test (HET-CAM). Bactericidal properties and inhibition of S. mutans biofilm formation were determined using a parallel-flow cell system and a dichromatic fluorescent stain. The percentage of viable cells was calculated from regression data generated from a viability standard. AgNP colloids proved to be non-irritating, as they were unable to promote vasoconstriction, haemorrhage or coagulation. AgNP colloids inhibited S. mutans biofilm formation on dental enamel, and cell viability measured by fluorescence was 0% for samples S1, S2, S3 and S4 and 36.5% for the positive control (diluted 30% silver diamine fluoride). AgNPs are new products with a low production cost because they have a lower concentration of silver, with low toxicity and an effective bactericidal effect against a cariogenic oral bacterium. Moreover, they do not promote colour change in dental enamel, which is an aesthetic advantage compared with traditional silver products.

Fluoride varnishes containing calcium glycerophosphate: fluoride uptake and the effect on in vitro enamel erosion.

OBJECTIVES: Calcium glycerophosphate (CaGP) was added to fluoride varnishes to analyze their preventive effect on initial enamel erosion and fluoride uptake: potassium hydroxide (KOH)-soluble and KOH-insoluble fluoride bound to enamel. MATERIALS AND METHODS: This study was carried out in two parts. Part 1: 108 enamel samples were randomly distributed into six varnish groups: base varnish (no active ingredients); Duraphat® (2.26%NaF); Duofluorid® (5.63%NaF/CaF2); experimental varnish 1 (1%CaGP/5.63 NaF/CaF2); experimental varnish 2 (5%CaGP/5.63%NaF/CaF2); and no varnish. Cyclic demineralization (90 s; citric acid, pH = 3.6) and remineralization (4 h) was made once a day, for 3 days. Change in surface microhardness (SMH) was measured. Part 2: 60 enamel samples were cut in half and received no varnish (control) or a layer of varnish: Duraphat®, Duofluorid®, experimental varnishes 1 and 2. Then, KOH-soluble and KOH-insoluble fluoride were analyzed using an electrode. RESULTS: After cyclic demineralization, SMH decreased in all samples, but Duraphat® caused less hardness loss. No difference was observed between varnishes containing CaGP and the other varnishes. Similar amounts of KOH-soluble and insoluble fluoride was found in experimental varnish 1 and Duofluorid®, while lower values were found for experimental varnish 2 and Duraphat®. CONCLUSION: The addition of CaGP to fluoride varnishes did not increase fluoride bound to enamel and did not enhance their protection against initial enamel erosion. CLINICAL RELEVANCE: We observe that the fluoride varnishes containing CaGP do not promote greater amounts of fluoride bound to enamel and that fluoride bound to enamel may not be closely related to erosion prevention.

Tolerance response of multidrug-resistant Salmonella enterica strains to habituation to Origanum vulgare L. essential oil.

Multidrug-resistant Salmonella enterica isolates from human outbreaks or from poultry origin were investigated for their ability to develop direct-tolerance or cross-tolerance to sodium chloride, potassium chloride, lactic acid, acetic acid, and ciprofloxacin after habituation in subinhibitory amounts ( of the minimum inhibitory concentration - (MIC) and of the minimum inhibitory concentration - MIC) of Origanum vulgare L. essential oil (OVEO) at different time intervals. The habituation of S. enterica to OVEO did not induce direct-tolerance or cross-tolerance in the tested strains, as assessed by the modulation of MIC values. However, cells habituated to OVEO maintained or increased susceptibility to the tested antimicrobials agents, with up to fourfold double dilution decrease from previously determined MIC values. This study reports for the first time the non-inductive effect of OVEO on the acquisition of direct-tolerance or cross-tolerance in multidrug-resistant S. enterica strains to antimicrobial agents that are largely used in food preservation, as well as to CIP, the therapeutic drug of salmonellosis.

Statistical investigation of Kluyveromyces lactis cells permeabilization with ethanol by response surface methodology

The aim of our study was to select the optimal operating conditions to permeabilize Kluyveromyces lactis cells using ethanol as a solvent as an alternative to cell disruption and extraction. Cell permeabilization was carried out by a non-mechanical method consisting of chemical treatment with ethanol, and the results were expressed as β-galactosidase activity. Experiments were conducted under different conditions of ethanol concentration, treatment time and temperature according to a central composite rotatable design (CCRD), and the collected results were then worked out by response surface methodology (RSM). Cell permeabilization was improved by an increase in ethanol concentration and simultaneous decreases in the incubation temperature and treatment time. Such an approach allowed us to identify an optimal range of the independent variables within which the β-galactosidase activity was optimized. A maximum permeabilization of 2,816 mmol L-1 oNP min-1 g-1 was obtained by treating cells with 75.0% v/v of ethanol at 20.0 °C for 15.0 min. The proposed methodology resulted to be effective and suited for K. lactis cells permeabilization at a lab-scale and promises to be of possible interest for future applications mainly in the food industry.

Statistical investigation of Kluyveromyces lactis cells permeabilization with ethanol by response surface methodology.

The aim of our study was to select the optimal operating conditions to permeabilize Kluyveromyces lactis cells using ethanol as a solvent as an alternative to cell disruption and extraction. Cell permeabilization was carried out by a non-mechanical method consisting of chemical treatment with ethanol, and the results were expressed as ß-galactosidase activity. Experiments were conducted under different conditions of ethanol concentration, treatment time and temperature according to a central composite rotatable design (CCRD), and the collected results were then worked out by response surface methodology (RSM). Cell permeabilization was improved by an increase in ethanol concentration and simultaneous decreases in the incubation temperature and treatment time. Such an approach allowed us to identify an optimal range of the independent variables within which the ß-galactosidase activity was optimized. A maximum permeabilization of 2,816 mmol L(-1) oNP min(-1) g(-1) was obtained by treating cells with 75.0% v/v of ethanol at 20.0 °C for 15.0 min. The proposed methodology resulted to be effective and suited for K. lactis cells permeabilization at a lab-scale and promises to be of possible interest for future applications mainly in the food industry.

Prevalence of dental anomalies in patients with cleft lip and palate, Paraiba, Brazil: clinic and radiographic study.

The aim of this study is to investigate the prevalence of dental anomalies in a group of individuals with different types of clefts attending the reference service in orthodontics for the care of patients with clefts in Paraiba state, northeastern Brazil. This was a cross-sectional, observational study. Two previously trained examiners (kappa = 0.89) performed the clinical examination of 76 patients with post and incisive transforamen unilateral or bilateral clefts, of both sexes, aged 4 to 32 years, and the analysis of periapical and panoramic radiographs from archived records of these patients. Only the upper front teeth were evaluated. Data were processed by descriptive statistics and subjected to statistical Chi-square test considered significant at 5%. Among the patients evaluated, males (57.9%) and left unilateral transforamen clefts (40.8%) were prevalent. Of the total 76 patients examined, 56 (73.68%) had at least one dental anomaly, the most frequent being agenesis (31.6%) and conical teeth (28.9%). The presence of anomalies differed significantly between the cleft and the contralateral sides (p<0.00001). The diagnosis and treatment of patients with clefts should therefore receive more attention. It is suggested that clinical and radiographic examination be performed together with careful planning and implementation of specialist services in an effort to provide early and adequate detection and treatment.

Estudo toxicológico pré-clínico (agudo) do extrato do Syzygium aromaticum (L) em roedores / Preclinical (acute) toxicologic study of the extract of Syzygium aromaticum (L) in rodents

O objetivo desta pesquisa foi estimar a toxicidade aguda do extrato do cravo-da-índia (Syzygium aromaticum Linné) em roedores. O extrato hidro-alcoólico a 80 por cento foi concentrado em evaporador rotativo obtendo-se uma mistura final de extrato pilular. Camundongos albinos (Mus musculus) fêmeas, divididos em 13 lotes de seis animais foram observados por 24 horas a partir da administração do extrato diluído em solução fisiológica a 0,9 por cento nas dosagens de 137,5; 180; 187,5; 250; 375; 437,5; 500 e 1.000 mg/kg para via intraperitoneal e 1.000; 2.400; 2.880; 4.000 e 5.000 mg/kg para via oral. O cálculo proporcional foi realizado a fim de se obter a mesma dose para todos os animais de cada grupo. As punções foram por via intraperitoneal sendo respeitados intervalos de cinco minutos entre as administrações individuais. Nos ensaios de toxicidade por via oral a solução foi introduzida no trato digestório dos animais através de cânula metálica acoplada a seringa (gavagem). Os animais apresentaram alguns sinais de toxicidade, porém não letais até a dose de 5.000 mg/kg. A DL50 para via intraperitoneal foi calculada pelo método de Karber e Behrens (1964), sendo estabelecida em 255 mg/kg (muito tóxico, grau 4). Conclui-se que sob condições agudas de exposição, o extrato do cravo-da-índia é um agente tóxico, devendo ser considerado como tal, dependendo da dose administrada ou absorvida, tempo e freqüência de exposição e vias de administração.

The objective of this research was to estimate the acute toxicity of the extract of clove (Syzygium aromaticum Linné) in rodents. The 80 percent hidro-alcoholic extract was concentrated in rotary evaporator until a final resinous mixture extract was obtained. Albino female mice (Mus musculus), divided in 13 lots of six animals were observed for 24 hours. The extract diluted in 0.9 percent physiologic solution was administrated at the dosages of 137.5; 180.0; 187.5; 250.0; 375.0; 437.5; 500.0 and 1,000 mg/kg through intraperitoneal route and 1000; 2,400; 2,880; 4,000 and 5,000 mg/kg through oral route. A proportional calculation was carried out in order to have the same dose for the animals in each group. The punctures were gotten by intraperitoneal route in intervals of five minutes among the individual doses. For the oral toxicity the solution was introduced in the digestive system of the animals through coupled metallic stem syringe (gavage). The animals presented non lethal toxic signs up to 5,000 mg/kg. DL50 was established by the method of Karber and Behrens (1964). LD50 was estimated in 255 mg/kg (highly poisonous, degree 4). It can be concluded that under acute conditions of exposure, the extract of clove is a poisonous agent and it should be considered as such, depending on the administered or absorbed dose, time and frequency exhibition and administration routes.

In vitro antimicrobial activity of Caesalpinia ferrea Martius fruits against oral pathogens.

AIM: In the Amazon region of Brazil, the fruits of Caesalpinia ferrea Martius (Brazilian ironwood) are widely used as an antimicrobial and healing medicine in many situations including oral infections. This study aimed to evaluate the antimicrobial activity of Caesalpinia ferrea Martius fruit extract against oral pathogens. MATERIALS AND METHODS: Polyphenols estimation and spectral analysis ((1)H NMR) of the methanol extract were carried out. The microorganisms Candida albicans, Streptococcus mutans, Streptococcus salivarius, Streptococcus oralis and Lactobacillus casei were tested using the microdilution method for planktonic cells (MIC) and a multispecies biofilm model. Chlorhexidine was used as positive control. RESULTS: Polyphenols in the extract were estimated at 7.3% and (1)H NMR analysis revealed hydroxy phenols and methoxilated compounds. MIC values for Candida albicans, Streptococcus mutans, Streptococcus salivarius, Streptococcus oralis and Lactobacillus casei were 25.0, 40.0, 66.0, 100.0, 66.0 microg/mL, respectively. For the biofilm assay, chlorhexidine and plant extract showed no growth at 10(-4) and 10(-5) microbial dilution, respectively. At 10(-4) and 10(-5) the growth values (mean+/-SD) of the negative controls (DMSO and saline solution) for Streptococcus mutans, Streptococcus sp. and Candida albicans were 8.1+/-0.7, 7.0+/-0.6 and 5.9+/-0.9 x 10(6)CFU, respectively. CONCLUSION: Caesalpinia ferrea fruit extract can inhibit in vitro growth of oral pathogens in planktonic and biofilm models supporting its use for oral infections.

Optimal activity and thermostability of xylose reductase from Debaryomyces hansenii UFV-170.

Xylose reductase (XR) is the enzyme that catalyzes the first step of xylose metabolism. Although XRs from various yeasts have been characterized, little is known about this enzyme in Debaryomyces hansenii. In the present study, response surface analysis was used to determine the optimal conditions for D. hansenii UFV-170 XR activity. The influence of pH and temperature, ranging from 4.0 to 8.0 and from 25 to 55 degrees C, respectively, was evaluated by a 2(2) central composite design face-centered. The F-test (ANOVA) and the Student's t test were performed to evaluate the statistical significance of the model and the regression coefficients, respectively. The NADPH-dependent XR activity varied from 0.502 to 2.53 U mL(-1), corresponding to 0.07-0.352 U mg(-1), whereas the NADH-dependent one was almost negligible. The model predicted with satisfactory correlation (R (2) = 0.940) maximum volumetric activity of 2.27 U mL(-1) and specific activity of 0.300 U mg(-1) at pH 5.3 and 39 degrees C, which were fairly confirmed by additional tests performed under these conditions. The enzyme proved very stable at low temperature (4 degrees C), keeping its activity almost entirely after 360 min, which corresponded to the half-time at 39 degrees C. On the other hand, at temperatures >or=50 degrees C it was lost almost completely after only 20 min.

Influence of cultivation conditions on xylose-to-xylitol bioconversion by a new isolate of Debaryomyces hansenii.

About 270 yeast isolates were screened for xylitol production using xylose as the sole carbon source. The best isolate, Debaryomyces hansenii UFV-170, released 5.84 g L(-1) xylitol from 10 g L(-1) xylose after 24 h, corresponding to a yield of xylitol on consumed substrate (Y(P/S)) of 0.54 g g(-1). This strain was cultivated batch-wise at variable starting concentrations of xylose (S(o)) and biomass (X(o)) and agitation intensity, in order to improve xylitol production and to evaluate, through simple carbon balances, the influence of these conditions on xylose metabolism. Under the best microaerobic conditions (S(o) = 53 g L(-1), X(o) = 1.4 g L(-1), 200 rpm), xylitol production reached 37.0 g L(-1), corresponding to xylitol volumetric productivity of 1.0 g L(-1)h(-1), specific productivity of 0.22 g g(-1)h(-1) and Y(P/S) = 0.76 g g(-1). Almost 83% of xylose was consumed for xylitol production, the rest being consumed for growth, while respiration was negligible. The new isolate appeared to be a promising alternative for industrial xylitol bioproduction.