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The syntheses of the title compounds were performed using lauric and myristic acids. The compounds obtained were characterized using 1H-, 13C-NMR and 2D 1H-1H COSY, 1H-13C HSQC NMR, IR, and high-resolution mass spectrometry. Both compounds exhibited bactericidal activity on S. aureus comparable to that of a reference drug (miramistin). Compound 10, with lauric acid fragment, had a 16-fold higher activity on P. aeruginosa compared to compound 11, which in turn contains myristic acid fragment (with minimum inhibitory concentrations of 32 and 512 μg/mL, respectively). Compound 11 exhibited a pronounced activity against all types of fungi (higher than the activity of miramistin), while the activity of compound 10 was considerably lower. Thus, compound 11 can serve as a promising antimicrobial agent for the treatment of various fungal and staphylococcal infections, while compound 10 is of interest to treat P. aeruginosa-associated infections. [ABSTRACT FROM AUTHOR]

Over the past decades, 2(5H)-furanone derivatives have been extensively studied because of their promising ability to prevent the biofilm formation by various pathogenic bacteria. Here, we report the synthesis of a series of optically active sulfur-containing 2(5H)-furanone derivatives and characterize their biological activity. Novel thioethers were obtained by an interaction of stereochemically pure 5-(l)-menthyloxy- or 5-(l)-bornyloxy-2(5H)-furanones with aromatic thiols under basic conditions. Subsequent thioethers oxidation by an excess of hydrogen peroxide in acetic acid resulted in the formation of the corresponding chiral 2(5H)-furanone sulfones. The structure of synthesized compounds was confirmed by IR and NMR spectroscopy, HRMS, and single crystal X-ray diffraction. The leading compound, 26, possessing the sulfonyl group and l-borneol moiety, exhibited the prominent activity against Staphylococcus aureus and Bacillus subtilis with MICs of 8 μg/mL. Furthermore, at concentrations of 0.4–0.5 μg/mL, the sulfone 26 increased two-fold the efficacy of aminoglycosides gentamicin and amikacin against S. aureus. The treatment of the model-infected skin wound in the rat with a combination of gentamicin and sulfone 26 speeded up the bacterial decontamination and improved the healing of the wound. The presented results provide valuable new insights into the chemistry of 2(5H)-furanone derivatives and associated biological activities. [ABSTRACT FROM AUTHOR]

Here, we report a synthesis of fluoroquinolones carrying a monoterpene moiety at the C7 position of aromatic structure. The minimal inhibitory concentrations of fluoroquinolone fused with trans-3-hydroxy-cis-myrtanylamine 18 against Staphylococcus aureus (MSSA isolates) were two- to eightfold lower compared to moxifloxacin, although fourfold higher against MRSA isolates. The fluoroquinolone fused with (-)-nopylamine 16 was four- to eightfold less active on MSSA compared to moxifloxacin, while had similar activity on MRSA. Against biofilms, both 16 and 18 were four times more active than both moxifloxacin and ciprofloxacin. Both 16 and 18 induced the drop of membrane potential and in silico exhibited similar binding energies with DNA gyrase of S. aureus (ΔG -13.44 to -13.17 kcal/mol), suggesting dual mechanism of action (topoisomerase inhibition by the fluoroquinolone core and membrane damage by the monoterpene fragment). Thus, our data demonstrate the perspectives of monoterpenes fusion to an antibiotic moiety to obtain dual-acting bipharmacophore antimicrobials with improved activity, including biofilm-associated infections., (© 2025 Wiley‐VHCA AG, Zurich, Switzerland.)

Among a variety of antimicrobial compounds, the derivatives of 2(5H)-furanone exhibit different effects on Firmicutes and Proteobacteria. While inhibiting quorum-dependent biofilm formation and virulence factor expression by Gram-negative bacteria through specific interference with the AI-2 signaling pathways, these compounds demonstrate bactericidal effects against Gram-positive bacteria. Here we report that 3,4-dichloro-5(S)-[(1S,2R,4S)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-yloxy]-2(5H)-furanone designed as F123 inhibits growth and biofilm formation by the food-poisoning bacterium Bacillus cereus at 8 μg/ ml and kills bacteria at 16 μg/ml. While the growth of Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus luteus, Bacillus subtilis were also inhibited at 8-16 μg/ml of F123, no bactericidal effect on these strains was observed at concentrations up to 128 μg/ml, suggesting pronounced specificity of F123 for B. cereus. In a checker-board assay F123 increased the efficacy of amikacin, gentamicin and benzalkonium chloride against B. cereus with medians of fractional inhibitory concentration index of 0.38, 0.56 and 0.56, respectively. Moreover, the number of viable B. cereus cells in biofilm was reduced by more than 3 orders of magnitude at 64 μg/ml of F123, suggesting its chemotype as a promising enhancer for specific treatment of B. cereus-associated topical infections, including biofilm-embedded bacteria.

The gram-positive opportunistic bacterium Staphylococcus aureus is one of the most common causatives of a variety of diseases including skin and skin structure infection or nosocomial catheter-associated infections. The biofilm formation that is an important virulence factor of this microorganism renders the antibiotic therapy ineffective, because biofilm-embedded bacteria exhibit strongly increased tolerance to antimicrobials. Here, we describe a novel 3-chloro-5( S )-[(1 R ,2 S ,5 R )-2-isopropyl-5-methylcyclohexyloxy]-4-[4-methylphenylsulfonyl]-2(5 H )-furanone ( F105 ), possessing a sulfonyl group and l -menthol moiety. Minimal inhibitory and bactericidal concentration values (MIC and MBC) of F105 were 10 and 40 mg/L, respectively, suggesting F105 biocidal properties. F105 exhibits pronounced activity against biofilm-embedded S. aureus and increases the efficacy of aminoglycosides (amikacin, gentamicin, and kanamycin) and benzalkonium chloride with fractional inhibitory concentration index values of 0.33-0.44 and 0.29, respectively, suggesting an alternative external treatment option, e.g., for wound infections. Moreover, low concentrations (0.5-1.3 mg/L) of F105 reduced the MICs of these antimicrobials twofold. By using confocal laser scanning microscopy and CFU counting, we show explicitly that F105 also restores the antimicrobial activity of gentamicin and ampicillin against S. aureus biofilms by several orders of magnitude. Biofilm structures were not destroyed but sterilized, with embedded cells being almost completely killed at twofold MBC. While F105 is quite toxic (CC 50 /MBC ratio 0.2), our data suggest that the F105 chemotype might be a promising starting point for the development of complex topical agents for combined anti-staphylococcal biofilm-therapies restoring the efficacy of some antibiotics against difficult to treat S. aureus biofilm.