Showing papers by "Rafael Guerra Lund published in 2016"

Cellulose Nanocrystal Membranes as Excipients for Drug Delivery Systems

Abstract: In this work, cellulose nanocrystals (CNCs) were obtained from flax fibers by an acid hydrolysis assisted by sonochemistry in order to reduce reaction times. The cavitation inducted during hydrolysis resulted in CNC with uniform shapes, and thus further pretreatments into the cellulose are not required. The obtained CNC exhibited a homogeneous morphology and high crystallinity, as well as typical values for surface charge. Additionally, CNC membranes were developed from CNC solution to evaluation as a drug delivery system by the incorporation of a model drug. The drug delivery studies were carried out using chlorhexidine (CHX) as a drug and the antimicrobial efficiency of the CNC membrane loaded with CHX was examined against Gram-positive bacteria Staphylococcus aureus (S. Aureus). The release of CHX from the CNC membranes is determined by UV-Vis. The obtaining methodology of the membranes proved to be simple, and these early studies showed a potential use in antibiotic drug delivery systems due to the release kinetics and the satisfactory antimicrobial activity.

Antimicrobial and cytotoxic evaluation of eugenol derivatives

Abstract: Eugenol is the major phenolic component of clove essential oil and it has been used in medical and dental practice for its properties like analgesic, local anesthetic, and antioxidant. It is known that eugenol can denature proteins and react with cell membrane phospholipids changing their permeability and inhibiting a great number of Gram-negative and Gram-positive bacteria as well as different types of yeast. Eugenol has ever demonstrated antimicrobial properties; thus, the search for the optimization through structural changes appears to be interesting for the development of new antimicrobials. This study aimed to evaluate the antimicrobial activity and cytotoxic characteristics of eugenol analogs. From natural eugenol, 14 derivatives were obtained by typical acylation and alkylation. Their antimicrobial activity was evaluated by the broth microdilution method. The compounds were assessed against Staphylococcus aureus ATCC 19095, Enterococcus faecalis ATCC 4083, Escherichia coli ATCC29214, Pseudomonas aeruginosa ATCC 9027, Candida albicans ATCC 62342 and the following clinical isolates from the human oral cavity: C. albicans (3), C. parapsilosis C. glabrata C. lipolytica, and C. famata. Cytotoxicity against mouse embryonic fibroblast (NIH/3T3) cell line was evaluated by MTT colorimetric assay. The majority of compounds demonstrated significant antimicrobial activities. In general, the compounds presented very low or no cytotoxicity, with an inhibitory ratio lower than 50 % against NIH/3T3 cell line.

Treatment of Fluorosis Spots Using a Resin Infiltration Technique: 14-month Follow-up.

Abstract: The aim of this study was to report a clinical case of moderate fluorosis spots treated with infiltration of low-viscosity resin. A commercial resin was applied to the facial surfaces on the anterior teeth in both the maxillary and mandibular arches. The white spots of fluorosis lost their whitish appearance and appeared similar to sound enamel. This technique, which might constitute an alternative to white-masking of fluorosis spots, showed optimal esthetic results.

(7-Chloroquinolin-4-yl)arylhydrazones: Candida albicans enzymatic repression and cytotoxicity evaluation, Part 2.

Abstract: Objective: This work describes the anti-enzymatic activity of (7-chloroquinolin-4-yl)arylhydrazones against Candida albicans and examines their cytotoxicity.Material and methods: Ten C. albicans strains [nine isolates and one azole-resistant standard strain (ATCC 62342)] were used to assess the anti-enzymatic activity. Fifteen compounds at sub-antifungal concentrations ranging from 12.5 to 100 µg/ml were assessed after a 30-min exposure. The strains were seeded onto petri dishes with selective agar media for aspartyl proteases (Saps) and phospholipases (PLs). Enzymatic inhibition was measured by the reduction of the precipitation zone (Pz) against untreated strains (positive control). A colorimetric MTT assay was used with 3T3/NIH mouse fibroblasts to evaluate cytotoxicity. Cells were exposed to 15 compounds in concentrations from 6.25 to 100 µg/ml for 24 and 48 h.Results: Four hydrazones showed enzymatic repression values over 40% to Pl and three over 20% to Saps. The cell viability was over 50% ...

In Vitro Cytotoxicity of Plantago australis Ethanol Extract Used as an Anti-Inflammatory for the Treatment of Oral Pathologies

Abstract: Background: Plantago australis Lam. is a plant native to southern Brazil largely used to reduce inflammation and improve the healing process. Interestingly, though, there are no previous studies evaluating the cytotoxicity of its ethanolic extract. Objectives: The main objective is to assess in vitro the cytotoxicity of the crude ethanolic extract of P. australis at dierent concen- trations. Materials and Methods: The MTT cytotoxicity assay was performed on a 3T3 mouse fibroblast cell line to measure the in vitro cyto- toxic activity of the crude formulation. Results: In vitro analysis showed that the greater the concentration of the extract, the greater the cytotoxicity. Conclusions: The crude extract of P. australis might be cytotoxic at high concentrations as evaluated against the cell line.

Experimental and Clinical Evaluation of Plantago australis Extract as an Anti-Inflammatory Agent to Treat Oral Pathologies

Abstract: Background: Plantago australis is a native plant from Southern Brazil used to reduce inflammation. Interestingly, there are no previous studies evaluating its use to treat oral lesions. Objectives: The study aimed to investigate in vivo the anti-inflammatory activity of 10% ethanol extract of P. australis in recurrent aphthous stomatitis (RAS), erosive lichen planus (ELP) and actinic cheilitis (AC). Methods: Thirty patients with RAS, ELP and AC were treated topically with 10% P. australis solution-based or cream. Results: In the comparison of in vivo data before and after the treatment and between different lesions, all P values were less than 0.05. Conclusions: The pharmaceutical formulation of 10% P. australis was therapeutically effective in the subjects with inflammatory oral lesions of RAS, ELP and AC.

Anti-candida and anti-enzyme activity and cytotoxicity of 2-phenyl-4H-chromen-4-one

Abstract: This study determined the fungicidal concentration (MFC), anti-enzymatic (production of proteinases and phospholipase), and cytotoxic activities of 2-phenyl-4H-chromen-4-one against different strains of Candida sp. The results were: MIC> 62.5 µg\ml and MFC>250 µg\ml for C. albicans; MIC/MFC = 31.25 µg\ml for C. parapsilosis; MIC/MFC= 62.5 µg/ml for C. famata; MIC/CFM =125 µg\ml for C. glabrata and MIC = 15.62 µg\ml for C. lipolytica. Values ​​for phospholipase and proteinase before and after exposure of yeast to the compound had no statistical differences. For the cytotoxicity test, there were no statistical differences between the tested and control groups. Data from this study provide evidence that 2-phenyl-4H-chromen-4-one could be an alternative source for the treatment of fungal infections caused by Candida. Key words: Candida albicans, antifungal activity, antifungal agents, anti-enzyme activity, flavone.

Removable orthodontic appliances: frequency and cleaning agents used by students and recommended by dentists

Abstract: Aim: To evaluate the prevalence and hygiene habits of 13-19 years-old adolescent users of removable orthodontic appliances (ROA) and to determine hygiene methods for the appliances prescribed by dentists, in the city of Pelotas. Methods: The study had two stages. The first stage was a telephone interview with dentists. Dentists were interview by telephone calls in order to obtain information regarding the hygiene methods for cleaning acrylic appliances. Second stage was a cross-sectional study performed with schoolchildren. Children from public and private schools with secondary level were included in the sample. A questionnaire was applied to the students using any type of ROA. Questionnaires included demographic information and behavioral characteristics. Data collected were subjected to Chi-square test and logistic regression. Results: The prevalence of children using ROA was 5.4%. Students (89.7%) and dentists (47.2%) reported to prefer mechanical methods to clean their ROA. Cleaning with soup, hydrogen peroxide or effervescent tabs were less used. High frequency of use was associated with higher frequency of hygiene on the ROA. Conclusions: The prevalence of schoolchildren using removable appliances was low. The common cleaning method used by children and prescribed by dentists was mechanical. Hygiene frequency was significantly associated with the routine of use of the appliance and with the type of hygiene method.