Propolis is a natural substance produced by bees and is known to have antimicrobial activity. Our aim was to evaluate the antimicrobial effect of micellar nanocomposites loaded with an ethyl acetate extract of Brazilian red propolis as a cavity cleaning agent and its influence on the color and microtensile bond strength (μTBS) of the dentin/resin interface. An ultra-performance liquid chromatography coupled with a diode array detector (UPLC-DAD) assay was used to determine the flavonoids and isoflavones present in an ethyl acetate extract of Brazilian red propolis (EARP) and micellar nanocomposites loaded with EARP (MNRP). The antimicrobial activity of EARP and MNRP was tested against Streptococcus mutans, Lactobacillus acidophilus, and Candida albicans. One of the following experimental treatments was applied to etched dentin (phosphoric acid, 15 s): 5 μL of MNRP (RP3, 0.3%; RP6, 0.6%; or RP1, 1.0% w/v), placebo, and 2% chlorhexidine digluconate. Single Bond adhesive (3 M/ESPE) was applied and a 4-mm-thick resin crown (Z350XT, 3 M/ESPE) was built up. After 24 h, the teeth were sectioned into sticks for the μTBS test and scanning electron microscopy. Spectrophotometry according to the CIE L*a*b* chromatic space was used to evaluate the color. Data were analyzed using one-way ANOVA and the Tukey test or Kruskal-Wallis test and the same test for pairwise comparisons between the means (P < 0.05). The UPLC-DAD assay identified the flavonoids liquiritigenin, pinobanksin, pinocembrin, and isoliquiritigenin and the isoflavonoids daidzein, formononetin, and biochanin A in the EARP and micellar nanocomposites. EARP and MNRP presented antimicrobial activity against the cariogenic bacteria Streptococcus mutans and Lactobacillus acidophilus, and for Candida albicans. ΔE values varied from 2.31 to 3.67 (P = 0.457). The mean μTBS for RP1 was significantly lower than for the other groups (P < 0.001). Dentin treated with RP1 showed the shortest resin tags followed by RP6 and RP3. The EARP and (MNRP) showed antimicrobial activity for the main agents causing dental caries (Streptococcus mutans and Lactobacillus acidophilus) and for Candida albicans. MNRP at concentrations of 0.3 and 0.6% used as a cavity cleaner do not compromise the aesthetics or μTBS of the dentin/resin interface.

Propolis is a natural product of honey bees whose chemical composition is influenced by different plant species and environmental factors, resulting in diverse biological activities. A new propolis type, the greenish-brown propolis (GBPUP), was identified in the northeast of Brazil. This study aimed to evaluate the influence of seasonal variation in the chemical composition of GBPUP extracts over a 12-month period. LC–ESI–Orbitrap–FTMS and UFLC–DAD–UV–Vis revealed a chemical composition with some differences to that of Brazilian green propolis, with pinocembrin as the major compound, followed by galangin, pinostrobin, chrysin, artepillin C, and pinobanksin. The extracts exhibited high levels of total phenolic, flavonoid, and flavanone contents and moderate to high antioxidant activity. Circos plot analysis showed that specific metabolites were responsible for the high activity against S. aureus (artepillin C, kaempferol, and ferulic acid) and C. albicans (galangin, pinobanksin, chrysin, and pinocembrin) and for moderate antibacterial activity against E. faecalis (rutin) and E. coli (luteolin, rutin, quercetin, and caffeic acid). ANOVA simultaneous component analysis (ASCA) showed a strong correlation between the metabolites (p-coumaric acid, artepillin C, luteolin) and leishmanicidal activity. Thus, seasonal evaluation allowed the identification of bioactive molecules, the months with greater bioactivity of the GBPUP extracts representing the first comprehensive study of the seasonality of this new and promising propolis variety.