Artepillin C, drupanin, and plicatin B are prenylated phenylpropanoids that naturally occur in Brazilian green propolis. In this study, these compounds and eleven of their derivatives were synthesized and evaluated for their in vitro antimicrobial activity against a representative panel of oral bacteria in terms of their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values. Plicatin B (2) and its hydrogenated derivative 8 (2′,3′,7,8-tetrahydro-plicatin B) were the most active compounds. Plicatin B (2) displayed strong activity against all the bacteria tested, with an MIC of 31.2 μg/mL against Streptococcus mutans, S. sanguinis, and S. mitis. On the other hand, compound 8 displayed strong activity against S. mutans, S. salivarius, S. sobrinus, Lactobacillus paracasei (MIC = 62.5 μg/mL), and S. mitis (MIC = 31.2 μg/mL), as well as moderate activity against Enterococcus faecalis and S. sanguinis (MIC = 125 μg/mL). Compounds 2 and 8 displayed bactericidal effects (MBC: MIC ≤ 4) against all the tested bacteria. In silico studies showed that the complexes formed by compounds 2 and 8 with the S. mitis, S. sanguinis, and S. mutans targets (3LE0, 4N82, and 3AIC, respectively) had energy score values similar to those of the native S. mitis, S. sanguinis, and S. mutans ligands due to the formation of strong hydrogen bonds. Moreover, all the estimated physicochemical parameters satisfied the drug-likeness criteria without violating the Lipinski, Veber, and Egan rules, so these compounds are not expected to cause problems with oral bioavailability and pharmacokinetics. Compounds 2 and 8 also had suitable ADMET parameters, as the online server pkCSM calculates. These results make compounds 2 and 8 good candidates as antibacterial agents against oral bacteria.

Background/Objectives: Dental caries and candidiasis are major health problems worldwide. Dental caries is caused by cariogenic bacteria, especially those belonging to the Streptococcus genus, whereas candidiasis is caused by Candida species. In this study, the antimicrobial activity of a series of synthetic N-methyl-4-piperidone-derived monoketone curcuminoids (MKCs) against Candida albicans, C. krusei, and a representative panel of cariogenic bacteria was assessed. Methods: Fifteen MKCs were synthesized using an environmentally friendly base-catalyzed Claisen–Schmidt condensation between an aromatic aldehyde (R-PhCHO) and N-methyl-4-piperidone ethanol using NaOH as the catalyst. These compounds were evaluated for their antibacterial activity against a representative panel of cariogenic bacteria, along with their antifungal activity against Candida krusei and C. albicans. The antimicrobial activity was determined based on the Minimum Inhibitory Concentration (MIC) values. Results: Most of the compounds were obtained in about 2 h in yields ranging from 40 to 70%. None of the compounds displayed antifungal activity, even at 100 μg/mL, the highest tested concentration. Similarly, none of the compounds were active against Enterococcus faecalis. On the other hand, compounds 1 (R = H), 10 (R = 3,4,5-OMe), and 13 (R = 3-F) displayed moderate activity against Streptococcus mutans (13), S. salivarus (1), L. paracasei (1 and 10), S. mitis (1, 10, and 13), S. sanguinis (1, 10, and 13), and S. sobrinus (13), with MIC values of 250 μg/mL and 500 μg/mL. The presence of the N-methyl-4-piperidone ring was found to boost the antibacterial activity as compared to the corresponding acetone-derived MKCs. Moreover, the antibacterial activity of compounds 10 and 13 was associated with the presence and position of the fluor atom and the methoxy groups at the aromatic ring. Conclusions: This study contributed to a better understanding of the antimicrobial activity of MKCs, whose data in the literature are still scarce.

The study evaluated the preservative potential of Lafoensia replicata Pohl. leaf extracts in cosmetics, highlighting their antioxidant, antimicrobial, and in vitro cytotoxic activities for ethanolic extract prepared by the maceration and tincture method. Total phenol content showed a higher phenol concentration in ethanolic extract and tinctures, and by LC-MS/MS-ESI-QTOF analysis, flavonoids, hydrolyzed tannins, and phenolic acids were identified. The ethanolic extract and tincture showed high antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans (MIC < 50 µg mL⁻¹), high antioxidant activity (EC₅₀ < 50 µg mL⁻¹ in the DPPH method, and results > 450 µmol trolox equivalent in the ABTS and FRAP method), and low cytotoxicity in human keratinocytes (IC₅₀ > 350 µg mL⁻¹). The results suggest these extracts could be an alternative to synthetic preservatives in the cosmetic industry.

Background/Objectives: Dental caries and candidiasis are major health problems worldwide. Dental caries is caused by cariogenic bacteria, especially those belonging to the Streptococcus genus, whereas candidiasis is caused by Candida species. In this study, the antimicrobial activity of a series of synthetic N-methyl-4-piperidone-derived monoketone curcuminoids (MKCs) against Candida albicans, C. krusei, and a representative panel of cariogenic bac-teria was assessed. Methods: Fifteen MKCs were synthesized using an environmentally friendly base-catalyzed Claisen-Schmidt condensation between an aromatic aldehyde (R-PhCHO) and N-methyl-4-piperidone ethanol us-ing NaOH as the catalyst. These compounds were evaluated for their antibacterial activity against a representative panel of cariogenic bacteria, along with their antifungal activity against Candida krusei and C. albicans. The antimi-crobial activity was determined based on the Minimum Inhibitory Concentration (MIC) values. Results: Most of the compounds were obtained in about 2 hours in yields ranging from 40 to 70%. None of the compounds displayed antifungal activity, even at 100 µg/mL, the highest tested concentration. Similarly, none of the compounds were active against Enterococcus faecalis. On the other hand, compounds 1 (R=H), 10 (R=3,4,5-OMe), and 13 (R=3-F) dis-played moderate activity against Streptococcus mutans (13), S. salivarus (1), L. paracasei (1 and 10), S. mitis (1, 10, and 13), S. sanguinis (1, 10, and 13), and S. sobrinus (13), with MIC values of 250 µg/mL and 500 µg/mL. The presence of the N-methyl-4-piperidone ring was found to boost the antibacterial activity as compared to the corresponding acetone-derived MKCs. Moreover, the antibacterial activity of compounds 10 and 13 was associated with the pres-ence and position of the fluor atom and the methoxy groups at the aromatic ring. Conclusions: This study contrib-uted to a better understanding of the antimicrobial activity of MKCs, whose data in the literature are still scarce.

Although Aspidosperma subincanum Mart. is traditionally used for metabolic and digestive disorders, its volatile nonpolar fraction remains unexplored. This study investigated n-hexane extracts from leaves (HE-GL) and stem bark (HE-GS), targeting antibacterial and enzyme-inhibitory activities based on ethnopharmacological use. GC-MS analysis revealed β-caryophyllene and aromadendrene as major constituents. HE-GL showed strong activity against Xanthomonas citri (MIC/MBC = 50 µg/mL), while HE-GS showed moderate effects (200 µg/mL). Both extracts exhibited acetylcholinesterase inhibition (IC₅₀ ≈ 80 µg/mL) and weak α-amylase and elastase inhibition (IC₅₀ ≥ 500 µg/mL). Cytotoxicity assays in human tumour (HeLa, MCF-7, U-251MG) and non-tumour (GM07492A) cell lines showed no effects up to 250 µg/mL. Molecular docking supported interactions with acetylcholinesterase and bacterial targets. These findings highlight the antibacterial and cholinesterase-modulating potential of A. subincanum volatiles.

Oral caries is a major global public health issue involving complex biofilm interactions and contributing to several systemic conditions. Metallic compounds have gained attention as antimicrobial agents due to their notable antibacterial activity. In this work, we investigated the anticariogenic potential of two copper(II) complexes containing Schiff base ligands, namely [CuCl(atc-Me)] (1, atc-Me = 2-acetylpyridine-N(4)-methyl-thiosemicarbazone) and [{Cu(μ‑atc‑Me)}2μ-SO4] (2). Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), minimum biofilm inhibitory concentration (MBIC50), and synergistic activity with chlorhexidine were evaluated. The in vivo toxicity of the complexes was further assessed using Caenorhabditis elegans. MBC values indicated a bactericidal effect for both complexes. Synergistic activity with chlorhexidine was observed against Streptococcus mutans and Enterococcus faecalis strains. Cytotoxic evaluation in human fibroblast cultures revealed that complexes 1 and 2 showed half maximal inhibitory concentration (IC50) values of 2.9 and 4.9 µg mL–1, respectively. Toxicity assays in C. elegans showed lethal concentration (LC50) values approximately three times higher than the MIC values for complexes 1 and 2. Molecular docking analyses revealed favorable binding energy values between the copper complexes and bacterial proteins. Overall, this investigation suggests an alternative approach for anticariogenic treatment, highlighting significant antibiofilm activity combined with low toxicity.