Anabela Portela Borges

Abstract Polypharmacological approaches have significant potential for the treatment of various complex diseases, including infectious bacteria-related diseases. Actually, multitargeting agents can achieve better therapeutic effects and overcome the drawbacks of monotherapy. Although multidrug multitarget strategies have demonstrated the ability to inactivate infectious bacteria, several challenges have been pointed out. In this way, multitarget direct ligands approaches appear to be a rational and sustainable strategy to combat antibiotic resistance. By combining different pharmacophores, antibiotic hybrids stand out as a promising application in the field of bacterial infections. These new chemical entities can achieve synergistic interactions that allow to extend the spectrum of action and target multiple pathways. In addition, antibiotic hybrids can reduce the likelihood of resistance development and provide improved chemical stability. It is worth highlighting that despite the efforts of the scientific community to discover new solutions for the most complex diseases, there is a significant lack of studies on biofilm-associated infections. This review describes the different polypharmacological approaches that can be used to treat bacterial infections with a particular focus, whenever possible, on those promoted by biofilms. By exploring these innovative approaches, we aim to inspire further research and progress in the search for effective treatments for infectious bacteria-related diseases, including biofilm-related ones. Significance Statement: The importance of the proposed topic lies in the escalating challenge of antibiotic resistance, particularly in the context of infectious bacteria-related infections. Polypharmacological approaches, such as antibiotic hybrids, represent innovative strategies to combat bacterial infections. By targeting multiple signaling pathways, these approaches not only enhance therapeutic effect but also reduce the development of resistance while improving the drug's chemical stability. Despite the urgent need to combat bacterial infectious diseases, there is a notable research gap, in particular in biofilmrelated ones. This review highlights the critical importance of exploring polypharmacological approaches with the aim of motivating further research and advances in effective treatments for infectious bacteria, including biofilm related infections.

Abstract Antimicrobial photodynamic inactivation (aPDI), using photosensitisers in combination with antibiotics, is a promising multi-target strategy to address antibiotic resistance, particularly in wound infections. This study aimed to elucidate the antibacterial mode of action of combinations of berberine (Ber) or curcumin (Cur) with selected antibiotics (Ber-Ab or Cur-Ab) under blue light irradiation (420 nm) against Staphylococcus aureus, including methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) strains. Multiple physiological parameters were assessed using complementary assays (fluorometry, epifluorescence microscopy, flame emission and atomic absorption spectroscopy, zeta potential, flow cytometry, and the plate agar method) to examine the effect on ROS production, membrane integrity, DNA damage, motility and virulence factors of S. aureus. Results indicated that blue light photoactivated Ber-Ab and Cur-Ab combinations led to substantial ROS generation, even at low concentrations, causing oxidative stress that severely impacted bacterial membrane integrity (approximately 90 % in MRSA and 40 % in MSSA). Membrane destabilization was further confirmed by elevated intercellular potassium release (approximate to 2.00 and 2.40 mu g/mL in MRSA and MSSA, respectively). Furthermore, significant DNA damage was observed in both strains (approximate to 50 %). aPDI treatment with blue light also reduced S. aureus pathogenicity by impairing motility and inhibiting key virulence factors such as proteases, lipases, and gelatinases, all of which play key roles in the infectious process. Overall, Ber-Ab combinations demonstrated the highest efficacy across all parameters tested, highlighting for the first time the multi-target therapeutic potential of this phytochemical-based aPDI strategy to combat antibiotic-resistant S. aureus infections and improve wound infection treatment outcomes.

Abstract The ability of Salmonella enterica subsp. enterica to persist and form biofilms on different surfaces can constitute a source of food contamination, being an issue of global concern. The objective of this study was to understand the biofilm formation profile of 14 S. enterica strains among different serovars and sources and to evaluate the ability of essential oil (EO) components (carveol, citronellol, and citronellal) to disinfect the biofilms formed on stainless steel and polypropylene surfaces. All the strains were able to form biofilms with counts between 5.34 to 6.78 log CFU cm(-2). Then, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of EO components were evaluated on two selected strains. All compounds inhibited the growth of Salmonella Typhimurium (strain 1; MIC = 800-1000 mu g ml(-1)) and Salmonella Enteritidis (strain 5; MIC = 400-1000 mu g ml(-1)) and only carveol showed bactericidal activity against strains 1 and 5 (MBC = 1200 mu g ml(-1)). Biofilms were exposed to the EO components at 10 x MIC for 30 min and polypropylene surfaces were more difficult to disinfect showing reductions between 0.9 and <1.2 log CFU cm(-2). In general, the S. enterica biofilms demonstrated a significant tolerance to disinfection, demonstrating their high degree of recalcitrance on food processing surfaces.

Abstract <jats:p>Manuel Simões was included as a corresponding author in the original publication [...]</jats:p>

Abstract Antibacterial resistance poses a critical public health threat, challenging the prevention and treatment of bacterial infections. The search for innovative antibacterial agents has spurred significant interest in quaternary heteronium salts (QHSs), such as quaternary ammonium and phosphonium compounds as potential candidates. In this study, a library of 49 structurally related QHSs was synthesized, varying the cation type and alkyl chain length. Their antibacterial activities against Staphylococcus aureus, including antibiotic-resistant strains, were evaluated by determining minimum inhibitory/bactericidal concentrations (MIC/MBC) <= 64 mu g/mL. Structure-activity relationship analyses highlighted alkyl-triphenylphosphonium and alkyl-methylimidazolium salts as the most effective against S. aureus CECT 976. The length of the alkyl side chain significantly influenced the antibacterial activity, with optimal chain lengths observed between C-10 and C-14. Dose-response relationships were assessed for selected QHSs, showing dose-dependent antibacterial activity following a non-linear pattern. Survival curves indicated effective eradication of S. aureus CECT 976 by QHSs at low concentrations, particularly compounds 1e, 3e, and 5e. Moreover, in vitro human cellular data indicated that compounds 2e, 4e, and 5e showed favourable safety profiles at concentrations <= 2 mu g/mL. These findings highlight the potential of these QHSs as effective agents against susceptible and resistant bacterial strains, providing valuable insights for the rational design of bioactive QHSs.