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Purpose: The aim of this study was to determine the antimicrobial effects of propolis extracted from an endemic species of stingless bee, T. sirindhornae, on the cariogenic bacterium Streptococcus mutans., Materials and Methods: Dichloromethane extracts (DME) of propolis (DMEP) were prepared and analysed by reverse-phase high-performance liquid chromatography. The antibacterial growth and antibiofilm formation effects of DMEP on S. mutans were compared with those of apigenin, a commercial propolis product. The effects of DMEP and apigenin on glucosyltransferase (gtf) B expression in S. mutans were investigated using real-time polymerase chain reaction. Chlorhexidine (CHX) was used as a positive control in the experiments., Results: Apigenin, pinocembrin, p-coumaric acid, and caffeic acid were not detected in the propolis extracts. DMEP and apigenin significantly inhibited S. mutans growth (IC50 = 43.5 and 17.36 mg/ml, respectively). DMEP and apigenin also exhibited antiadherence effects on S. mutans as shown by reduced biofilm formation. Furthermore, a significant inhibition in gtfB expression was observed in DMEP and apigenin treated S. mutans., Conclusion: Propolis produced by T. sirindhornae demonstrated antibacterial and antibiofilm effects, and reduced gtfB expression in S. mutans. The antibacterial activities of propolis observed were not due to apigenin, pinocembrin, p-coumaric acid, or caffeic acid.

Propolis is a material manufactured by bees and contains beeswax, bee salivary secretions and plant resins. Propolis preparations have been used for millennia by humans in food, cosmetics and medicines due to its antibacterial effects. Within the hive, propolis plays an important role in bees' health, with much of its bioactivity largely dependent on the plant resins the bees select for its production. Few chemical studies are available on the chemistry of propolis produced by Australian honeybees (Apis mellifera, Apidae). This study aimed to determine the chemical composition as well as in vitro antimicrobial effects of propolis harvested from honeybees in subtropical eastern Australia. Honeybee propolis was produced using plastic frames and multiple beehives in two subtropical sites in eastern Australia. Methanolic extracts of propolis were analysed by liquid chromatography with ultraviolet detection and high-resolution mass spectrometry (ultra-high-pressure liquid chromatography (UHPLC)-UV-high-resolution tandem mass spectrometry (HR-MS/MS)) and by gas chromatography mass spectrometry (GC-MS). The resulting chemical data were dereplicated for compound characterisation. The two crude extracts in abs. ethanol were tested in vitro by the agar diffusion and broth dilution methods, using a phenol standard solution as the positive control and abs. ethanol as the negative control. Chemical constituents were identified to be pentacyclic triterpenoids and C-prenylated flavonoids, including Abyssinoflavanone VII, Propolin C and Nymphaeol C. The two propolis crude extracts showed bactericidal effects at the minimal inhibitory concentrations of 0.37-2.04 mg mL(-1) against Staphylococcus aureus ATCC 25923. However, the extracts were inactive against Klebsiella pneumoniae ATCC 13883 and Candida albicans ATCC 10231. The antistaphylococcal potential of propolis was discussed, also in relation to honeybees' health, as it warrants further investigations on the social and individual immunities of Australian honeybees.

Yeasts isolated from patients with superficial mycoses were tested against propolis samples collected from different regions and honeybee races. The minimum inhibitory concentration (MIC) values obtained using the agar dilution methods were compared to the diameters of growth inhibition zones by using the disk diffusion method. The results showed that Candida albicans, C. glabrata, Trichosporon spp., and Rhodotorula sp. were susceptible to low concentrations of propolis, the latter showing a higher susceptibility. Relative to the other propolis tested, the propolis sample collected by Apis mellifera caucasica possessed the highest antifungal activity against all of the superficial mycoses. In contrast, the propolis samples collected by A.m. carnica and A.m. anatolica were the least active samples. Also, the propolis sample from the Adana region is more active than samples from other regions. An increase of MIC values was accompanied by a decrease of growth inhibition zone diameters.

Extracts from different samples of Brazilian propolis were obtained by Soxhlet extraction or maceration at room temperature using ethanol, water, and accombination of both solvents. Analysis of their composition using HPLC revealed that no major differences were seen when a propolis sample was subject to different extraction methods. The activity of the 15 extracts was assayed against bloodstream trypomastigotes of Trypanosoma cruzi, the etiologic agent of Chagas' disease. Multivariate analysis was applied to evaluate the efficiency of the different extracts and the trypanocidal activity. The extracts could be divided into two groups. In the first, in which, extracts were obtained by reflux in Soxhlet using 100% ethanol, there was a lower content of bioactive compounds and consequently lower trypanocidal activity. Extract 136-Et100 stands out in this group, since it had the highest levels of bioactive compounds together with highest activity against the parasite when compared with all other extracts. The second group comprises extracts with intermediate levels of bioactive compounds and higher activity against T. cruzi.

The composition of propolis, a resinous hive product collected by honeybees from various plant sources, depends on various factors such as season and vegetation of the area. Based on standards (either isolated from Brazilian propolis or reported from propolis) including chromane, diterpenes and phenolic compounds, different Brazilian propolis were analysed by LC-MS in order to determine their chemical constituents. Dicaffeoylquinic acids were detected in almost all water extracts of Brazilian propolis, whereas diterpenes, flavonoids and prenylated phenolic compounds were found in their methanol extracts. Based on the identified chemical constituents and their biological activities, it was determined that the quality of Brazilian propolis could be directly related to the phenolic constituents. Moreover, Baccharis dracunculifolia was concluded to be an important source of Brazilian propolis. Propolis samples from Peru, China and the Netherlands were also studied.