Abstract
BackgroundNative bees of the tribe Meliponini produce a distinct kind of propolis called geopropolis. Although many pharmacological activities of propolis have already been demonstrated, little is known about geopropolis, particularly regarding its antimicrobial activity against oral pathogens. The present study aimed at investigating the antimicrobial activity of M. fasciculata geopropolis against oral pathogens, its effects on S. mutans biofilms, and the chemical contents of the extracts. A gel prepared with a geopropolis extract was also analyzed for its activity on S. mutans and its immunotoxicological potential.MethodsAntimicrobial activities of three hydroalcoholic extracts (HAEs) of geopropolis, and hexane and chloroform fractions of one extract, were evaluated using the agar diffusion method and the broth dilution technique. Ethanol (70%, v/v) and chlorhexidine (0.12%, w/w) were used as negative and positive controls, respectively. Total phenol and flavonoid concentrations were assayed by spectrophotometry. Immunotoxicity was evaluated in mice by topical application in the oral cavity followed by quantification of biochemical and immunological parameters, and macro-microscopic analysis of animal organs.ResultsTwo extracts, HAE-2 and HAE-3, showed inhibition zones ranging from 9 to 13 mm in diameter for S. mutans and C. albicans, but presented no activity against L. acidophilus. The MBCs for HAE-2 and HAE-3 against S. mutans were 6.25 mg/mL and 12.5 mg/mL, respectively. HAE-2 was fractionated, and its chloroform fraction had an MBC of 14.57 mg/mL. HAE-2 also exhibited bactericidal effects on S. mutans biofilms after 3 h of treatment. Significant differences (p < 0.05) in total phenol and flavonoid concentrations were observed among the samples. Signs toxic effects were not observed after application of the geopropolis-based gel, but an increase in the production of IL-4 and IL-10, anti-inflammatory cytokines, was detected.ConclusionsIn summary, geopropolis produced by M. fasciculata can exert antimicrobial action against S. mutans and C. albicans, with significant inhibitory activity against S. mutans biofilms. The extract with the highest flavonoid concentration, HAE-2, presented the highest antimicrobial activity. In addition, a geopropolis-based gel is not toxic in an animal model and displays anti-inflammatory effect.
Highlights
Native bees of the tribe Meliponini produce a distinct kind of propolis called geopropolis
Agar diffusion tests showed the antimicrobial action of geopropolis extracts (HAE-2 and hydroalcoholic extracts (HAEs)-3), with inhibition zones ranging from 10 to 13 mm for S. mutans and from 9 to 13 mm for C. albicans
Since HAE-2 presented a lower minimum bactericidal concentrations (MBCs) than the other extracts and since the pathogenesis of the cariogenic process is related to the formation of a dental biofilm, we investigated whether this extract was able to inhibit the viability of S. mutans biofilms
Summary
Native bees of the tribe Meliponini produce a distinct kind of propolis called geopropolis. Distinct pharmacological activities of propolis have been demonstrated, including antimicrobial, anti-inflammatory, antitumor, cytotoxic, hepatoprotective and immunomodulatory properties, among others [2,3,4]. Known pharmacological activities generally refer to propolis produced by Apis mellifera, the most common bee species in many countries and the main producer of honey in those countries [7]. Some of these activities have been observed in propolis produced by other bee species, including members of the tribe Meliponini [6,8]. The final product is used in a similar manner as propolis produced by A. mellifera [11]
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