RESUMO
A flavonoids-free Brazilian propolis (type 6) showed biological effects against mutans streptococci and inhibited the activity of glucosyltransferases. This study evaluated the influence of the ethanolic extract of a novel type of propolis (EEP) and its purified hexane fraction (EEH) on mutans streptococci biofilms and the development of dental caries in rats. The chemical composition of the propolis extracts were examined by gas chromatography/mass spectrometry. The effects of EEP and EEH on Streptococcus mutans UA159 and Streptococcus sobrinus 6715 biofilms were analysed by time-kill and glycolytic pH drop assays. Their influence on proton-translocating F-ATPase activity was also tested. In the animal study, the rats were infected with S. sobrinus 6715 and fed with cariogenic diet 2000. The rats were treated topically twice a day with each of the extracts (or control) for 5 weeks. After the experimental period, the microbial composition of their dental plaque and their caries scores were determined. The results showed that fatty acids (oleic, palmitic, linoleic and stearic) were the main compounds identified in EEP and EEH. These extracts did not show major effects on the viability of mutans streptococci biofilms. However, EEP and EEH significantly reduced acid production by the biofilms and also inhibited the activity of F-ATPase (60-65%). Furthermore, both extracts significantly reduced the incidence of smooth surface caries in vivo without displaying a reduction of the percentage of S. sobriuns in the animals' plaque (P < 0.05). However, only EEH was able to reduce the incidence and severity of sulcal surface caries (P < 0.05). The data suggest that the cariostatic properties of propolis type 6 are related to its effect on acid production and acid tolerance of cariogenic streptococci; the biological activities may be attributed to its high content of fatty acids.
Assuntos
Cariostáticos/farmacologia , Cárie Dentária/prevenção & controle , Própole/farmacologia , Streptococcus mutans/efeitos dos fármacos , Adenosina Trifosfatases/metabolismo , Animais , Aderência Bacteriana/efeitos dos fármacos , Abelhas , Biofilmes , Brasil , Cariostáticos/química , Cárie Dentária/microbiologia , Placa Dentária/microbiologia , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Glicólise , Concentração de Íons de Hidrogênio , Testes de Sensibilidade Microbiana , Própole/química , Distribuição Aleatória , Ratos , Ratos Wistar , Streptococcus mutans/enzimologiaRESUMO
This study was designed to test whether free radicals are involved in the deleterious effects of compressed gases on cells. The actions of xenon, nitrous oxide, argon, nitrogen, helium, and oxygen and their effects on the toxicity of paraquat (methyl viologen) were studied using Escherichia coli. Growth of E. coli in trypticase-soy broth in an atmosphere of 1.36 MPa (13.6 atm) N2O resulted in an induction of superoxide dismutase (SOD). In addition, when SOD was induced by oxygen, the resulting cells had increased resistance to the killing action of N2O. The toxicity of paraquat was increased in the presence of N2O but not He, N2, or Ar. However, addition of any of the latter three gases to N2O resulted in increased toxicity of paraquat beyond that due to N2O alone. Oxygen is known to increase the reaction of paraquat radicals within cells and to reduce leakage of the radicals out through the cell membrane. N2O and Xe seem to have this same action, and He, N2, or Ar could enhance the actions of N2O, Xe, or O2. The data indicate that the inhibitory and lethal actions of these gases may be due to enhanced reactivity of radicals with cell components and reduced leakage of the radicals to the environment.