Antimicrobial activity of Rheedia brasiliensis and 7-epiclusianone against Streptococcus mutans.

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-acetate and ethanolic extracts obtained (concentrations ranging from 6.25 to 800 microg/ml) were tested against S. mutans UA159 through MIC/MBC assays. S. mutans 5-days-old biofilms were treated with the active extracts (100 x MIC) for 0, 1, 2, 3 and 4h (time-kill) and plated for colony counting (CFU/ml). Active extracts were submitted to exploratory chemical analyses so as to isolate and identify the bioactive compound using spectroscopic methods. The bioactive compound (concentrations ranging from 0.625 to 80 microg/ml) was then tested through MIC/MBC assays. Peel 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 4h, certifying of the bioactive compound 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 microg/ml; MBC: 10-20 microg/ml). The results indicated that 7-epiclusianone may be used as a new 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.

Chemical composition and biological activity of a new type of Brazilian propolis: red propolis.

Propolis has been used as a medicinal agent to treat infections and promote wound healing for centuries. The aim of the present study was to test the antimicrobial, antioxidant, and cytotoxic activities of a new type of Brazilian propolis, popularly called red propolis, as well as to analyze its chemical composition. The antimicrobial activity against Staphylococcus aureus ATCC 25923 and Staphylococcus mutans UA159 was evaluated and the chloroform fraction (Chlo-fr) was the most active with lower MIC ranging from 25 to 50 microg/ml. The hexane fraction (H-fr), having the highest concentration of total flavonoids, showed the best sequestrating activity for the free radical DPPH. The ethanolic extract of propolis (EEP) showed cytotoxic activity for the HeLa tumor cells with an IC(50) of 7.45 microg/ml. When the EEP was analyzed by GC-MS, seven new compounds were found, among which four were isoflavones. Our results showed that the red propolis has biologically active compounds that had never been reported in other types of Brazilian propolis.

Effects of Mikania genus plants on growth and cell adherence of mutans streptococci.

The present study evaluated the chemical composition and the antimicrobial activity of the extracts and fractions of Mikania laevigata and Mikania glomerata on growth and cell adherence of mutans streptococci. Ethanolic extract, hexane and ethyl acetate fractions of Mikania laevigata and Mikania glomerata were chemically identified by chromatographic methods and tested on mutans streptococci from culture collection and clinical isolates. Twenty-two compounds were identified in both Mikania extracts, including coumarin, 1-octadecene, and diterpenic, cupressenic and kaurenoic acids. Antimicrobial activity was assessed by determination of the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and inhibition of cell adherence to a glass surface. Hexane fraction from both plant extracts was the most effective in inhibiting the growth of the bacterial strains tested (MIC values between 12.5 microg/ml and 400 microg/ml, and MBC values between 25 microg/ml and 400 microg/ml). In addition, sub-MIC levels of the crude extracts and their hexane fractions significantly inhibited the adherence of the microorganisms to a glass surface. The data indicate that the biologically active compounds are present mostly in the hexane fraction of both Mikania species, which showed remarkable inhibitory activities against mutans streptococci. Mikania genus plant is a promising source for novel antimicrobial agents against oral pathogens.

In situ effect of frequent sucrose exposure on enamel demineralization and on plaque composition after APF application and F dentifrice use.

Since the effect of the combination of methods of fluoride use on enamel demineralization and on plaque composition is not clearly established, this study examined the effect of the combination of acidulated phosphate fluoride (APF) application and F dentifrice on enamel demineralization and on plaque composition. In this crossover study, 16 volunteers, wearing a palatal appliance containing bovine enamel blocks, were subjected to 4 treatment groups: non-fluoridated dentifrice (PD), FD, APF+PD, and APF+FD. The APF was applied to the enamel before the 14-day experimental period. During the experimental period, test dentifrices were applied 3x/day, and a 20% sucrose solution was applied 4x and 8x/day by being dripped on the blocks. Although APF application was able either to increase F concentration in plaque or to reduce the % of mutans streptococci, its combination with F dentifrice use neither reduced enamel mineral loss nor changed any other measured plaque variable with respect to the FD group alone.

Effects of Apis mellifera propolis on the activities of streptococcal glucosyltransferases in solution and adsorbed onto saliva-coated hydroxyapatite.

Propolis, a resinous hive product collected by Apis mellifera bees, has been used for thousands of years in folk medicine. Ethanolic extracts of propolis (EEP) have been shown to inhibit the activity of a mixture of crude glucosyltransferase (Gtf) enzymes in solution. These enzymes synthesize glucans from sucrose, which are important for the formation of pathogenic dental plaque. In the present study, the effects of propolis from two different regions of Brazil on the activity of separate, purified Gtf enzymes in solution and on the surface of saliva-coated hydroxyapatite (sHA) beads were evaluated. The EEP from Minas Gerais (MG; Southeastern Brazil) and Rio Grande do Sul (RS; Southern Brazil) were tested for their ability to inhibit the enzymes GtfB (synthesis of insoluble glucan), GtfC (insoluble/soluble glucan) and GtfD (soluble glucan). The effects of propolis on Gtf from Streptococcus sanguis (soluble glucan synthesis) was also explored. The EEP from both regions effectively inhibited the activity of all Gtfs in solution (75-95%) and on the surface of sHA beads (45-95%) at concentrations between 0.75 and 3.0 mg of propolis/ml. However, the two samples of propolis showed different levels of inhibition on each of the enzymes tested. In general, EEP RS demonstrated a significantly higher inhibitory activity on GtfB and C activities (both solution and surface assays) than EEP MG at concentrations between 0.047 and 0.187 mg/ml (p<0.05). EEP MG, on the other hand, exhibited a greater inhibitory effect on the activities of surface GtfD (at 0.375, 0.75 and 1.5 mg/ml) and S. sanguis Gtf (at 1.5 and 3.0 mg/ml; p<0.05). These data indicate that EEP is a potent inhibitor of Gtf enzymes in solution and adsorbed on an experimental pellicle; however, its effect on Gtf activity is variable depending on the geographical origin of the propolis samples. There is a need to identify the active compounds of propolis.

In vitro antimicrobial activity of propolis and Arnica montana against oral pathogens.

Arnica and propolis have been used for thousands of years in folk medicine for several purposes. They possess several biological activities such as anti-inflammatory, antifungal, antiviral and tissue regenerative, among others. Although the antibacterial activity of propolis has already been demonstrated, very few studies have been done on bacteria of clinical relevance in dentistry. Also, the antimicrobial activity of Arnica has not been extensively investigated. Therefore the aim here was to evaluate in vitro the antimicrobial activity, inhibition of adherence of mutans streptococci and inhibition of formation of water-insoluble glucan by Arnica and propolis extracts. Arnica montana (10%, w/v) and propolis (10%, w/v) extracts from Minas Gerais State were compared with controls. Fifteen microorganisms were used as follows: Candida albicans--NTCC 3736, F72; Staphylococcus aureus--ATCC 25923; Enterococcus faecalis--ATCC 29212; Streptococcus sobrinus 6715; Strep. sanguis--ATCC 10556; Strep. cricetus--HS-6; Strep. mutans--Ingbritt 1600; Strep. mutans--OMZ 175; Actinomyces naeslundii--ATCC 12104, W 1053; Act. viscosus OMZ 105; Porphyromonas gingivalis; Porph. endodontalis and Prevotella denticola (the last three were clinical isolates). Antimicrobial activity was determined by the agar diffusion method and the zones of growth inhibition were measured. To assess cell adherence to a glass surface, the organisms were grown for 18 h at 37 degrees C in test-tubes at a 30 degree angle. To assay water-insoluble glucan formation, a mixture of crude glucosyltransferase and 0.125 M sucrose was incubated for 18 h at 37 degrees C in test-tubes at a 30 degree angle. Arnica and propolis extracts (20 microl) were added to these tubes to evaluate the % of inhibition of cell adherence and water-insoluble glucan formation. The propolis extract significantly inhibited all the microorganisms tested (p < 0.05), showing the largest inhibitory zone for Actinomyces spp. The Arnica extract did not demonstrate significant antimicrobial activity. Cell adherence and water-insoluble glucan formation were almost completely inhibited by the propolis extract at a final concentration of 400 microg/ml and 500 microg/ml, respectively. The Arnica extract showed slight inhibition of the adherence of the growing cells (19% for Strep. mutans and 15% for Strep. sobrinus) and of water-insoluble glucan formation (29%) at these same concentrations. Thus, the propolis extract showed in vitro antibacterial activity, inhibition of cell adherence and inhibition of water-insoluble glucan formation, while the Arnica extract was only slightly active in those three conditions.

Effect of Apis mellifera propolis from two Brazilian regions on caries development in desalivated rats.

The purpose of the present study was to evaluate the effect of Apis mellifera propolis collected from two regions of Brazil on caries development in desalivated rats. Ethanolic extracts of propolis (EEP) were prepared from crude propolis samples collected in Minas Gerais state (MG), southeastern Brazil, and Rio Grande do Sul state (RS), southern Brazil. The flavonoid composition of EEP was analyzed by high-performance thin-layer chromatography (HPTLC) and reversed-phase high-performance liquid chromatography (HPLC). For the animal study, 30 specific pathogen-free Wistar rats were infected with Streptococcus sobrinus 6715 and surgically desalivated. The rats were randomly divided into three groups which were treated with 80% ethanol (control), EEP from MG and EEP from RS. The animals were placed in a König-Höfer programmed feeder and received 17 meals of diet 2000 daily at hourly intervals. The solutions were applied on the rat molars (25 microl on molars of each quadrant) twice a day, by using graduate syringes. After 3 weeks, the animals were killed by CO(2) asphyxiation. For microbial assessment, the left jaw was removed and sonicated in 154 mM NaCl solution. Dental caries was evaluated according to Larson's modification of Keyes' system. The HPTLC patterns and HPLC profiles demonstrated that both quality and quantity of flavonoid aglycones of EEP from MG were different compared to EEP from RS. In general, it is apparent that EEP from RS contained the highest concentrations of pinocembrin, chrysin, acacetin and galangin. The group of animals treated with EEP from RS showed the lowest smooth-surface and sulcal caries scores as well as less caries severity in smooth-surface and sulcal lesions, and these data were statistically different when compared with the control group. The group treated with EEP from MG only demonstrated a significant difference in the severity of sulcal lesions when compared to the control group. The percentage of S. sobrinus was lower in the groups treated with EEP, but did not differ statistically from the control group. The results showed that the cariostatic effect of propolis depends on its composition, and consequently the region of collection of propolis samples.