Percorrer por autor "Ferreira, Susana"
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- 5-Hydrazinylethylidenepyrimidines effective against multidrug-resistant Acinetobacter baumannii: Synthesis and in vitro biological evaluation of antibacterial, radical scavenging and cytotoxic activitiesPublication . Figueiredo, Joana; Serrano, João L.; Soares, MN; Ferreira, Susana; Domingues, F.C.; Almeida, Paulo; Silvestre, SamuelAcinetobacter baumannii has emerged as an important nosocomial pathogen in recent years, with infectious outbreaks caused by multidrug-resistant strains increasing worldwide. Thus, new antibacterial treatments for multidrug-resistant A. baumannii strains are needed. In this work, a series of 5-hydrazinylethylidenepyrimidines were synthesized and in vitro evaluated against two multidrug-resistant A. baumannii strains (AcB 13/10 and AcB 73/10). Minimum inhibitory concentration results demonstrated that generally the compounds in study presented values in a low micromolar range. In the determination of in vitro bacterial growth at 24 h, it was observed that the pyrimidines 3a and 3c, with an unsubstituted hydrazinylphenyl, have bacteriostatic activity in both multidrug-resistant A. baumannii strains, with a concentration-dependent action. In general, an additive effect occurred in the combination of these compounds with gentamicin, rifampicin and polymyxin B, for both strains. Furthermore, all 5-hydrazinylethylidenepyrimidines under study presented a good 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, generally low xanthine oxidase inhibition and low cytotoxicity in normal human dermal fibroblasts as well as potential favorable drug-likeness properties. Thus, these molecules can be considered attractive for the future development of antibacterial agents against multidrug-resistant A. baumannii.
- Antimicrobial and antitumor activity of S-methyl dithiocarbazate Schiff base zinc(II) complexesPublication . Gomes, Filipa Ramilo; Addis, Yemataw; Tekamo, Israel; Cavaco, Isabel; Campos, Débora L.; Pavan, Fernando R.; Gomes, Clara S.B.; Brito, Vanessa; Santos, Adriana O.; Domingues, F.C.; Luís, Ângelo; Marques, M. Matilde; Pessoa, João Costa; Ferreira, Susana; Silvestre, Samuel; Correia, IsabelSchiff bases (SB) obtained from S-methyl dithiocarbazate and aromatic aldehydes: salicylaldehyde (H2L1), o-vanillin (H2L2), pyridoxal (H2L3) and 2,6-diformyl-4-methylphenol (H3L4), and their corresponding Zn(II)-complexes (1-4), are synthesized. All compounds are characterized by elemental analyses, infrared, UV-Vis, nuclear magnetic resonance spectroscopy and mass spectrometry. The structures of H2L2 and [Zn2(L1)2(H2O)(DMF)] (1a) (DMF = dimethylformamide) are solved by single crystal X-ray diffraction. The SB coordinates the metal center through the Ophenolate, Nimine and Sthiolate atoms. The radical scavenging activity is tested using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, with all ligand precursors showing IC50 values ~40 μM. Cytotoxicity studies with several tumor cell lines (PC-3, MCF-7 and Caco-2) as well as a non-tumoral cell line (NHDF) are reported. Interestingly, 1 has relevant and selective antiproliferative effect against Caco-2 cells (IC50 = 9.1 μM). Their antimicrobial activity is evaluated in five bacterial strains (Klebsiella pneumoniae, Acinetobacter baumannii, Listeria monocytogenes, Pseudomonas aeruginosa and Staphylococcus aureus) and two yeast strains (Candida albicans and Candida tropicalis) with some compounds showing bacteriostatic and fungicidal activity. The minimal inhibitory concentration (MIC90) of HnL against Mycobacterium tuberculosis is also reported, with H2L2 and H3L4 showing very high activity (MIC90 < 0.6 μg/mL). The ability of the compounds to bind bovine serum albumin (BSA) and DNA is evaluated for H3L4 and [Zn2(L4)(CH3COO)] (4), both showing high binding constants to BSA (ca. 106 M-1) and ability to bind DNA. Overall, the reported compounds show relevant antitumor and antimicrobial properties, our data indicating they may be promising compounds in several fields of medicinal chemistry.
- Antimicrobial, antibiofilm and cytotoxic activities of Hakea sericea Schrader extractsPublication . Luís, Ângelo; Breintenfeld, Luiza; Ferreira, Susana; Duarte, Ana Paula; Domingues, F.C.Background: Hakea sericea Schrader is an invasive shrub in Portuguese forests. Objective: The goal of this work was to evaluate the antimicrobial activity of H. sericea extracts against several strains of microorganisms, including the ability to inhibit the formation of biofilms. Additionally the cytotoxic properties of these extracts, against human cells, were assessed. Materials and Methods: The antimicrobial activity of the methanolic extracts of H. sericea was assessed by disk diffusion assay and Minimum Inhibitory Concentration (MIC) value determination. The antibiofilm activity was determined by quantification of total biofilm biomass with crystal violet. Cytotoxicity was evaluated by hemolysis assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test. Results: For Gram-positive bacteria, MIC values of H. sericea methanolic extracts ranged between 0.040 and 0.625 mg/mL, whereas the fruits extract yielded the lowest MIC for several strains of microorganisms, namely, S. aureus, B. cereus, L. monocytogenes and clinical methicillin-resistant S. aureus (MRSA). Stems and fruits extract at 2.5 mg/mL effectively eradicated the biofilm of S. aureus ATCC 25923, SA 01/10 and MRSA 12/10. Regarding leaves extract, hemolysis was not observed, and in the case of stems and fruits, hemolysis was verified only for higher concentrations, suggesting its low toxicity. Fruits extract presented no toxic effect to normal human dermal fibroblasts (NHDF) cells however for concentrations of 0.017 and 0.008 mg/mL this extract was able to decrease human breast adenocarcinoma cells (MCF-7) viability in about 60%, as MTT test results had confirmed. This is a clearly demonstrator of the cytotoxicity of this extract against MCF-7 cells.
- Antioxidant and antimicrobial activity and potential of heather (Erica spp.) extracts in the control of Listeria monocytogenesPublication . Santos, Anabela; Luís, Ângelo; Ferreira, Susana; Duarte, Ana PaulaIn this work, heather and its flowers were studied regarding their antioxidant and antimicrobial activities. Plants were subjected to ultrasound‐assisted methanolic extraction followed by fractionation. A phytochemical characterisation of extracts content in total phenols and flavonoids, and their antioxidant activity was performed. The antimicrobial activity was evaluated through the determination of minimum inhibitory concentration and by bioautography. Following, studies on the antilisterial potential were carried out by: time‐kill curves, inhibition of biofilm formation and tolerance of Listeria monocytogenes to adverse conditions. The results evidenced the antioxidant activity in both extracts, as well as, the antimicrobial activity against Gram‐positive bacteria. Concerning the evaluation of the antilisterial potential, a bacteriostatic behaviour and inhibition of biofilms formation ability were observed. Listeria monocytogenes showed an increased susceptibility to adverse conditions when preincubated with extracts. Thus, heather and its flowers may be a source of new compounds with antilisterial activity potential.
- Arcobacter butzleri Ciprofloxacin Resistance: Point Mutations in DNA Gyrase A and Role on Fitness CostPublication . Ferreira, Susana; Correia, Daniela R.; Oleastro, Mónica; Domingues, F.C.Arcobacter butzleri is a widely distributed emerging pathogen resistant to various classes of antimicrobial agents, namely fluoroquinolones. A. butzleri resistance to fluoroquinolones is conferred by point mutations at the antibiotic target. The aim of this study was to evaluate mutations at gyrA associated with ciprofloxacin resistance and evaluate whether acquisition of resistance impacts on fitness and stress tolerance of A. butzleri. A. butzleri ciprofloxacin mutants were generated by laboratory induction. Identification of mutations associated with ciprofloxacin resistance was performed by gyrA sequencing. Growth kinetics, cost of fitness, biofilm formation ability, and stress tolerance were assessed. Two amino acid substitutions in the quinolone resistance-determining region of GyrA were identified in the mutant strains, one previously described (Thr-85-Ile) and a new substitution (Asp-89-Tyr). No differences in growth kinetics were recorded between parental and mutant strains; however, fitness cost was variable, according to the genetic background of the strains, and independently of ciprofloxacin resistance. Overall, the ciprofloxacin resistance development did not significantly affect stress tolerance, motility, or biofilm-forming ability. In conclusion, acquisition of ciprofloxacin resistance in A. butzleri is associated with mutations in gyrA and is likely well compensated, with cost of fitness reflecting the diversity in genetic background of this bacterium.
- Arcobacter spp. at retail food from Portugal: Prevalence, genotyping and antibiotics resistancePublication . Martins, Sofia Vicente; Oleastro, Mónica; Domingues, F.C.; Ferreira, SusanaArcobacter genus is considered a foodborne emergent pathogen able to cause disease among humans and animals. The wide distribution and high prevalence of Arcobacter in food is becoming a concern, since consumption of contaminated food and water is considered the most probable route of Arcobacter transmission to humans. In this work, ready-to-eat packaged vegetables, poultry, pork, beef and fish meat were purchased from several retail markets and supermarkets and tested for the presence of Arcobacter spp. Suspected colonies were isolated and identified, characterized through ERIC-PCR and resistance to nine antibiotics commonly used to treat infections by this microorganism was assessed; in parallel, Arcobacter spp. was directly detected on enrichment broth by multiplex PCR. The results show a high prevalence of Arcobacter spp. among retail food, with an overall prevalence of 60.5% obtained by both molecular and culture detection. A. butzleri was the most frequently isolated species (58.5%) followed by A. cryaerophilus (35.8%) and A. skirrowii (5.7%). A high genetic diversity among the isolates was observed, despite the detection of a possible cross-contamination between food samples. Also, a high rate of multidrug resistance among the isolates (85.7%) was observed. Taken together, our results suggest that the consumption of Arcobacter-contaminated food products is of public health concern.
- Arcobacter spp. in Food Chain-From Culture to OmicsPublication . Ferreira, Susana; Oleastro, Mónica; Domingues, F.C.
- Assessment of the Antimicrobial Activity of L. and (L.) DC Extracts and Their Synergistic Potential with Conventional Antibiotics AgainstPublication . Coimbra, Alexandra; Luís, Ângelo; Gaspar, Pedro Dinis; Ferreira, Susana; Duarte, Ana Paula; Hadjikakou, Sotiris K.This study aimed to evaluate the antibacterial activity of L. and (L.) DC extracts against , including methicillin-resistant (MRSA) strains. To this end, assays were conducted to assess killing kinetics, antibiotic combination effects, modulatory effects on ethidium bromide, inhibition of quorum sensing, and biofilm formation. extract demonstrated the strongest activity, with MIC values ranging from 7.8 to 62.5 µg/mL. When combined with antibiotics such as ampicillin, ciprofloxacin, or vancomycin, the extracts of and predominantly exhibited synergistic (FICI value ≤ 0.5) or additive effects (0.5 < FICI ≤ 1), with some combinations resensitizing resistant strains. The aerial parts of displayed modulatory effects on ethidium bromide MIC, reducing the concentration from 32 to 8 µg/mL, suggesting efflux pump inhibitory activity. In addition, this extract displayed slight quorum-sensing inhibition at a concentration of 125 µg/mL. Moreover, and extracts inhibit the formation of biofilm by strains, even at subinhibitory concentrations (0.5× and 0.25× MIC). The presence of compounds such as myricetin 3 -galactoside, catechin derivatives, gallic acid, kaempferol, and chlorogenic acid in the extracts may contribute to their anti- activity. These results demonstrated the dual antimicrobial and antivirulence potential of and extracts, highlighting their promise as therapeutic agents or adjuvants against These extracts can be promising candidates for further studies on the development of novel strategies targeting multiple pathogenic pathways.
- Bioactive Potential of Wild Plants from Gardunha Mountain: Phytochemical Characterization and Biological ActivitiesPublication . Coimbra, Alexandra; Gallardo, Eugenia; Luís, Ângelo; Gaspar, Pedro Dinis; Ferreira, Susana; Duarte, Ana Paula; Adriana, IrinelThe plants used in folk medicine have been increasingly studied to identify their bioactive properties. Therefore, this study aimed to assess the bioactivity of the hydroethanolic extracts of plants collected in Gardunha Mountain, Portugal. Seven abundant and representative wild plants were studied: , , , , , , and . The phytochemical composition of the extracts was determined by UHPLC-timsTOF-MS and by spectrophotometric methods. The antioxidant, in vitro anti-inflammatory and antimicrobial activity and the biocompatibility of the extracts were tested. The extracts were predominantly composed of flavonoids and phenolic acids, such as gallic acid, neochlorogenic acid and quercetin glycosides. The extracts demonstrated very strong antioxidant activity related to scavenging free radicals (AAI = 2.84 and 2.93). Regarding antimicrobial activity, the extract exhibited inhibitory effects, particularly against Gram-positive bacteria and yeasts (MIC = 0.008-0.5 mg/mL). The , , and extracts showed low cytotoxicity (viability > 70%) in the highest concentration tested. These findings highlight and as promising sources of novel bioactive compounds, particularly antimicrobials in controlling microbial growth and promoting associated health benefits, and underscore the value of traditional medicinal plants as a guide for pharmacological studies.
- Clinical isolates of Acinetobacter baumannii from a Portuguese hospital: PFGE characterization, antibiotic susceptibility and biofilm-forming abilityPublication . Duarte, Andreia; Ferreira, Susana; Almeida, Sofia; Domingues, F.C.Acinetobacter baumannii is an emerging pathogen associated with nosocomial infections that in addition has shown an increasing resistance to antibiotics. In this work the genetic diversity of A. baumannii isolates from a Portuguese hospital, their antibiotic resistance profiles and ability to form biofilms was studied. Seventy-nine clinical A. baumannii isolates were characterized by pulsed-field gel electrophoresis (PFGE) with 9 different PFGE profiles being obtained. Concerning the antimicrobial susceptibility, all A. baumannii isolates were resistant to 12 of the 17 tested antibiotics and classified as multidrug-resistant (MDR). In addition, 74.7% of the isolates showed biofilm formation ability, however no statistical significance with antibiotic resistance was observed. In contrast, urine samples isolates were more likely to form biofilms than strains isolated from other sources. Our findings highlight the high number of MDR A. baumannii isolates and the importance of the formation of biofilms as a potential virulence factor.