Navegando por Autor "Almeida, Luciana Salles Branco de"

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Antimicrobial activity of Rheedia brasiliensisand 7-epiclusianone against Streptococcus mutans.
(2008) Almeida, Luciana Salles Branco de; Murata, Ramiro Mendonça; Yatsuda, Regiane; Santos, Marcelo Henrique dos; Nagem, Tanus Jorge; Alencar, Severino Matias de; Koo, Hyun; Rosalen, Pedro Luiz
This in vitro study evaluated the antimicrobial activity of extracts obtained from Rheedia brasiliensis fruit (bacupari) and its bioactive compound against Streptococcus mutans. Hexane, ethyl-acet ate and ethanolic extracts obtained (concentrations ranging from 6.25 to 800mg/ml) were tested against S. mutans UA1 59 through MIC /MBC assays. S. mutans5-days -old biofilm s were treat ed with the active extra cts (100 MIC ) for 0, 1, 2, 3 an d 4 h (time-k ill) and plate d for colony counting (CFU/m l). Active extracts were submitted to exploratory chemical analyses so as to isolate and identify the bioactive compound using spectroscopic method s. The bioactive compo und (concentration s ranging from 0.625 to 80mg/ml) was then tested through MIC /MBC assays . Pee l and seed hexane extracts showed antimicrobial activity against planktonic cells at low concentrations and were thus selected for the time kill test. These hexane extracts reduced S. mutans biofilm viability after 4 h, certifying of the bioactive compo und presence. The bioactive compound identified was the polyprenylated benzophenone 7-epiclusianone, which showed a good antimicrobial activity at low concentrations (MIC : 1.25–2 .5 mg/ml; MBC: 10–20mg/ml). The results indicated that 7-epi clusian one may be used as a ne w agent to control S. mutans biofilms; however, more studies are needed to further elucidate the mechanisms of action and the anticariogenic potential of such compound found in R. brasiliensis.
Inhibitory efects of 7-epiclusianone on glucan synthesis, acidogenicityand biofilm formation by Streptococcus mutans.
(2008) Murata, Ramiro Mendonça; Almeida, Luciana Salles Branco de; Yatsuda, Regiane; Santos, Marcelo Henrique dos; Nagem, Tanus Jorge; Rosalen, Pedro Luiz; Koo, Hyun
The aim of this study was to examine the effects of 7-epiclusianone, a new prenylated benzophenone isolated from the plant Rheedia gardneriana, on some of the virulence properties of Streptococcus mutans associated with biofilm development and acidogenicity. The synthesis of glucans by glucosyltransferases B (GTF B) and C (GTF C) was markedly reduced by 7-epiclusianone showing more than 80% inhibition of enzymatic activity at a concentration of 100 mgmL 1. Doublereciprocal analysis (Lineweaver–Burk plots) revealed that the inhibition of GTF B activity was noncompetitive (mixed) while GTF C was inhibited uncompetitively. The glycolytic pH drop by S. mutans cells was also disrupted by 7-epiclusianone without affecting the bacterial viability, an effect that can be attributed, in part, to inhibition of F-ATPase activity (61.1 3.0% inhibition at 100 mgmL 1). Furthermore, topical applications (1-min exposure, twice daily) of 7-epiclusianone (at 250 mgmL 1) disrupted biofilm formation and physiology. The biomass (dryweight), extracellular insoluble polysaccharide concentration and acidogenicity of the biofilms were significantly reduced by the test agent (Po0.05). The data show that 7-epiclusianone disrupts the extracellular and intracellular sugar metabolism of S. mutans, and holds promise as a novel, naturally occurring compound to prevent biofilm-related oral diseases.