Assessment of cytotoxic and antimicrobial activities of two components of Cymbopogon citratus essential oil

There is a continuing search for compuounds to improve the chemical plaque inhibitory action of oral hygiene products. Although the antibacterial effects of chlorhexidine (CHX) and essential oils components, citral/myrcene, have been described, there is contradictory information regarding their cytotoxic effects in host tissues. This study aimed to evaluate the cytotoxic activity of the major components of the oil C. citratus, citral and myrcene on human periodontal ligament fibroblast (HPLF) cultures and their antimicrobial effect on different bacterial species present in supragingival biofilm. Cytotoxicity of the compounds to HPLF was determined by MTT assay. Antimicrobial activity was tested against reference strains of Enterococcus faecalis, Streptococcus mutans and Lactobacillus rhamnosus and for S. mutans clinical strains by broth microdilution assay. One-way analysis of variance (ANOVA) with Games-Howell post-hoc multiple comparison or unpaired t tests were used for inter- and intragroup comparisons. Overall, all of the compounds under study showed a cytotoxic effect to HPLF which varied in a dose-dependant manner. Whilst myrcene did not show bacteriostatic activity at tested concentrations, both citral and CHX exhibited bacteriostatic/bactericidal effects to all strains at specific concentrations, being CHX most effective to inhibit bacterial growth at lower concentrations than what observed for citral. Based on these findings, it would possible to conclude that whereas myrcene might be ineffective to control bacterial growth, citral could have a promising antimicrobial activity against dental colonizers with low cytotoxicity, and may be useful for preventing the onset and progression of oral diseases

In Silico Selection and In Vitro Evaluation of New Molecules That Inhibit the Adhesion of <i>Streptococcus mutants</i> through Antigen I/II

Streptococcus mutans is the main early colonizing cariogenic bacteria because it recognizes salivary pellicle receptors. The Antigen I/II (Ag I/II) of S. mutans is among the most important adhesins in this process, and is involved in the adhesion to the tooth surface and the bacterial co-aggregation in the early stage of biofilm formation. However, this protein has not been used as a target in a virtual strategy search for inhibitors. Based on the predicted binding affinities, drug-like properties and toxicity, molecules were selected and evaluated for their ability to reduce S. mutans adhesion. A virtual screening of 883,551 molecules was conducted; cytotoxicity analysis on fibroblast cells, S. mutans adhesion studies, scanning electron microscopy analysis for bacterial integrity and molecular dynamics simulation were also performed. We found three molecules ZINC19835187 (ZI-187), ZINC19924939 (ZI-939) and ZINC19924906 (ZI-906) without cytotoxic activity, which inhibited about 90% the adhesion of S. mutans to polystyrene microplates. Molecular dynamic simulation by 300 nanoseconds showed stability of the interaction between ZI-187 and Ag I/II (PDB: 3IPK). This work provides new molecules that targets Ag I/II and have the capacity to inhibit in vitro the S. mutans adhesion on polystyrene microplates

Caries dental en adultos jóvenes en relación con características microbiológicas y fisicoquímicas de la saliva

Objetivo Determinar la relación entre características fisicoquímicas de la saliva, el recuento de microorganismos cariogénicos, bacterias anaerobias facultativas y gram negativas, con la experiencia de caries en adultos jóvenes.Materiales y Métodos Se recolectó saliva total estimulada de 120 estudiantes de odontología entre 17 y 34 años de edad, para el análisis de tasa de flujo salivar, pH, concentraciones de iones de calcio y fosfato, ácido láctico, recuento de microorganismos cariogénicos, bacterias facultativas y gram negativas.Resultados La tasa de flujo salivar se incluyó en el intervalo biológico de referencia y no se asoció con la presencia de caries dental, lo mismo sucedió con los niveles de ácido láctico. Se encontró relación directamente proporcional entre las concentraciones de calcio y fosfato y la presencia de caries. Los recuentos de Estreptococos del grupo Mutans se relacionaron con la presencia de lesiones de mancha blanca; Lactobacillusspp, bacterias anaerobias facultativas y gram negativas se asociaron a presencia de lesiones cavitacionales de caries.Conclusiones En el grupo de adultos jóvenes evaluado, las características fisicoquímicas y microbiológicas de las saliva se relacionan de manera diferencial con la presencia de caries dental en diferentes grados de avance