Percorrer por autor "Rodrigues, Maria Elisa"
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- Glycyrrhiza glabra hydroethanolic extract and manuka honey alone and in combination inhibit bacterial and fungal planktonic cells and biofilmsPublication . Gomes, Fernanda; Dias, Maria Inês; Rodrigues, Maria Elisa; Barros, Lillian; Henriques, MarianaThe natural tendency of polymicrobial infections and co-habitation of bacteria and Candida are currently well-recognized and reported as highly fatal. This kind of interaction is usually associated with drug tolerance, infection relapse, persistence and high mortality. The interest in natural products has emerged and their potential applicability as therapeutic strategies is being constantly explored. Purpose: The main goal of this work is to evaluate the effect of the hydroethanolic extract of Glycyrrhiza glabra, and Manuka honey, in Staphylococcus aureus and Candida tropicalis planktonic cells and single and mixed biofilms. Methods: The effect of both the G. glabra extract and the honey was evaluated by determination of the minimum inhibitory/bactericidal/fungicidal concentrations and by determination of their antibiofilm activity (alone and in combination) on single and mixed-species biofilms. In addition, phenolic compounds were characterized in the hydroethanolic extract with high performance liquid chromatography and mass spectrometry. Results: Among the phenolic compounds identified in the G. glabra extract, flavonoids were the most abundant (≈75 % of the total phenolic compounds), with liquiritigenin being the most representative. S. aureus and C. tropicalis were susceptible to both antimicrobials acting alone. When tested in combination, a significative synergism was observed against C. tropicalis single biofilm formation. Instead, the combination showed an additive effect against mixed biofilms of S. aureus and C. tropicalis. In general the combination G. glabra+honey showed a broader antibiofilm effect than each partner alone. Conclusion: The results showed the good anti S. aureus and C. tropicalis effect of G. glabra and manuka honey against both pathogens tested and highlighted their potential use in combination as therapeutic strategy to combat S. aureus, C. tropicalis and mixed species infections particularly when growing as biofilms.
- Phenolic plant extracts versus penicillin G: In vitro susceptibility of Staphylococcus aureus isolated from bovine mastitisPublication . Gomes, Fernanda; Rodrigues, Maria Elisa; Martins, Natália; Ferreira, Isabel C.F.R.; Henriques, MarianaAntibiotics are the elective drugs in bovine mastitis (BM) treatment, despite their low rates of e ciency and e ectiveness and increasing risk of pathogen resistance. In this sense, it is urgent to discover new and e ective antimicrobial agents to apply in BM control and even treatment. Plant extracts have been widely recognized as a rich source of phytochemicals with antimicrobial potential. Thus, the present work aims to compare the bioactivity of Eucalyptus globulus and Juglans regia extracts against Staphylococcus aureus bovine mastitis strains with penicillin G. At non-toxic concentrations, E. globulus exerted a bacteriostatic e ect in planktonic cells and J. regia had no antimicrobial activity. Penicillin G, at minimum inhibitory concentration (MIC), demonstrated bactericidal activity, but just for S. aureus 3, 5, 6 and ATCC 25923, while the other strains seem to have acquired resistance. On the other hand, E. globulus and penicillin G in combination demonstrated synergy, being the most e ective approach against S. aureus 1, 2 and 4. Thus, penicillin alone and in combination with E. globulus or J. regia seems to be promissory strategies to control bovine mastitis infections.
- Plant phenolic extracts as an effective strategy to control Staphylococcus aureus, the dairy industry pathogenPublication . Gomes, Fernanda; Martins, Natália; Barros, Lillian; Rodrigues, Maria Elisa; Oliveira, Beatriz; Henriques, Mariana; Ferreira, Isabel C.F.R.Staphylococcus aureus is one of the most common contagious mastitis pathogens. Bovine mastitis is considered an important reservoir for dairy industry contamination, and therefore to ensure S. aureus control has gained a pivotal importance. Natural matrices present multiple biological effects, being its antimicrobial potential increasingly reported. Thus, the present study aims to assess the antibacterial activity of several methanol:water extracts, obtained from plants, against Staphylococcus aureus. Moreover, the most effective extract was characterized in terms of phenolic compounds, by using high performance liquid chromatography coupled to diode array and mass spectrometer detectors. Among the tested extracts, Eucalyptus globulus was the most effective against all tested S. aureus strains, followed by Juglans regia and Foeniculum vulgare. Inhibition halos of the plant extracts varied between 8.0–16.0 mm, excepting for F. vulgare in which two evident halos were observed: one with growth inhibition (5.0–7.0 mm) and a second one with visible cell density reduction (13.0–14.0 mm). Susceptibility assays evidenced that E. globulus extract exerted the highest antibacterial activity (MICs = 0.195–0.39 mg/mL), being effective against all the tested strains. Among the phenolic compounds identified in this extract, gallotannins, ellagic acid glycoside, and quercetin derivatives, were the most abundant; and therefore, may exert a positive and contributive effect to the observed antibacterial effect. Overall, the use of plant extracts to control bovine mastitis caused by S. aureus is a promising solution that could contribute to the reduction of the occurrence of dairy food industry contaminations, providing considerable benefits to agro-industries on the formulation of high-quality and safety dairy products.
- Satureja montana L. And origanum majorana L. decoctions: Antimicrobial activity, mode of action and phenolic characterizationPublication . Gomes, Fernanda; Dias, Maria Inês; Lima, Ângela; Barros, Lillian; Rodrigues, Maria Elisa; Ferreira, Isabel C.F.R.; Henriques, MarianaMedicinal and aromatic plants are known to have a wide range of uses and health benefits, and should be exploited for their bioactivity. Here we evaluated the antimicrobial activity of decoctions of Satureja montana L. and Origanum majorana L. against Gram-positive and Gram-negative bacteria and Candida spp. as well as their mechanism of action and phenolic characterization. The Satureja montana and Origanum majorana extracts were effective against a broad set of species, including the Gram-positive Staphylococcus aureus, Enterococcus faecalis, and Streptococcus dysgalactiae and the Gram-negative Klebsiella pneumoniae and Pseudomonas aeruginosa. Both extracts were found to have rosmarinic acid as the main phenolic compound and to exert their antimicrobial activity at the level of the cell membrane. Membrane perturbations by the extracts impaired cell membrane integrity only a few hours after exposure. This study confirms the bioactive potential of Satureja montana and Origanum majorana decoctions, and supports the development of novel formulations with wide antimicrobial properties based on these medicinal and aromatic herbs.