Browsing by Author "Henriques, Mariana"
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- Activity of phenolic compounds from plant origin against Candida speciesPublication . Martins, Natália; Barros, Lillian; Henriques, Mariana; Silva, Sónia; Ferreira, Isabel C.F.R.Candida albicans and other Candida species have been highly associated with several opportunistic fungal infections. Their ability to develop host infections is incited by different determinants, being virulence factors the most highlighted. Molecular targets of the antifungal drugs are crucial components for determination of yeast survival. Ergosterol, nucleic acids and glucan are the most studied molecular targets to destroy Candida species, being considered the basis of the development of new antifungal drugs. However, increasing levels of resistant Candida species to the current antifungal drugs have been observed, making ineffective those agents. Thus, other therapies more effective and safer than the current ones, are being studied, namely the use plant of extracts enriched in phenolic compounds. In this sense, this manuscript provide an historical perspective of the opportunistic fungal infections, molecular targets of the current anti-Candida drugs, as well as a general description of the active principles present in plants, focused on the antifungal potential of whole plant extracts and isolated phenolic compounds, against Candida species.
- Anti-biofilm activity of hydromethanolic plant extracts against Staphylococcus aureus isolates from bovine mastitisPublication . Gomes, Fernanda; Martins, Natália; Ferreira, Isabel C.F.R.; Henriques, MarianaBovine mastitis (BM) presents a high incidence, being Staphylococcus aureus one of the major causative agents. Antibiotics comprise the most common therapeutic approach, but due to their indiscriminate use, high rates of increasingly resistant bacterial species have been markedly pointed out. Particularly, S. aureus possesses a pronounced ability to form biofilms, and therefore, are of pivotal interest due to its alarming pathogenicity. The present study investigates the antibacterial properties of Eucalyptus globulus methanol: water extracts, alone and in combination with Juglans regia, against S. aureus isolates from BM. All isolates and reference strain proved to be good biofilm producers after 24 h of bacterial growth. Individually, the studied plant extracts (PE) lead to a considerable biofilm cells reduction, but their combination revealed to be the most effective strategy. When tested in combination, both extracts led to a 3 and 5 log reduction for S. aureus ATCC 25923 and S. aureus 1, respectively. Based on these findings, both PE seem to be promissory antimicrobial agents for upcoming use on dairy industry contaminations, BM and even S. aureus-triggered food poisoning. Further studies are needed to understand which of the compounds present in the extracts are responsible for the observed effects, including their corresponding modes of action.
- Antibacterial potential of Northeastern Portugal wild plant extracts and respective phenolic compoundsPublication . Pinho, Eva; Ferreira, Isabel C.F.R.; Barros, Lillian; Carvalho, Ana Maria; Soares, Graça; Henriques, MarianaThe present work aims to assess the antibacterial potential of phenolic extracts, recovered from plants obtained on the North East of Portugal, and of their phenolic compounds (ellagic, caffeic, and gallic acids, quercetin, kaempferol, and rutin), against bacteria commonly found on skin infections. The disk diffusion and the susceptibility assays were used to identify the most active extracts and phenolic compounds. The effect of selected phenolic compounds on animal cells was assessed by determination of cellular metabolic activity. Gallic acid had a higher activity, against gram-positive (S. epidermidis and S. aureus) and gram-negative bacteria (K. pneumoniae) at lower concentrations, than the other compounds. The caffeic acid, also, showed good antibacterial activity against the 3 bacteria used. The gallic acid was effective against the 3 bacteria without causing harm to the animal cells. Gallic and caffeic acid showed a promising applicability as antibacterial agents for the treatment of infected wounds.
- Antifungal activity against Candida species and phenolic characterization of decoction, infusion and hydroalcoholic extract of cultivated Salvia officinalis L.Publication . Martins, Natália; Barros, Lillian; Silva, Sónia; Santos-Buelga, Celestino; Henriques, Mariana; Ferreira, Isabel C.F.R.The freq uency and severity of diagnosed fungal infections is growing and, linked with thi s, it is observed an exacerbated increase of the antifungal drugs resistance. Candida albicans has been considered the main agent responsible for opportunistic pathogenic infections, but, recently, other non-C. albicans Candida species have also been considered [1]. In face to the increased number of Candida species drug resistant, it is crucial to use natural matrices to discover efficient alternative therapies to current antifungal agents. Salvia officina /is L., commonly known as sage, could be one of those natural matrices, containing a wide variety of bioactive molecules. Despite the existence of some reports on antimicrobial activity of sage, the most stud ied preparation is the essential oil, being scarce the aqueous extracts. The antifungal activity of decoction, infusion and hydroalcoholic extract of cultivated sage were evaluated, and further characterized in terms of phenolic composition (HPLC- DAD- ESIIMS). Antifungal activity was assessed against a total of 19 Candida strains of C. albicans, C. tropicalis, C. parapsilosis and C. glabrata recovered from different human biological samples. The most pronounced effect was observed against C. parapsilosis, fo llowed by C. tropicalis and C. albicans. No effect was observed against the three C. glabrata stra ins. In general, decoction presented the most pronounced effect, followed by infusion and hydroalcoholic extract, varying directly according with the extract concentration. Decoction also showed the highest concentration in phenolic compounds, followed by hydroalcoholic extract and infusions. Rosmarinic acid and luteolin 7-0-glucuronide were the main phenolic compounds. Thus, the use of sage decoction, incorporated on daily food dietary, or even as complement to an antifungal therapy, could provide considerable benefits, not only by internal but also external use, without the common side effects reported for essential oil.
- Antifungal activity and detailed chemical characterization of Cistus ladanifer phenolic extractsPublication . Barros, Lillian; Dueñas, Montserrat; Alves, Carlos Tiago; Silva, Sónia; Henriques, Mariana; Santos-Buelga, Celestino; Ferreira, Isabel C.F.R.The life-threatening mycoses caused by opportunistic fungal pathogens (mainly species from the genus Candida) associated with nosocomial infections, are one of the major health problems in our days. Therefore, it is crucial to identify new compounds, especially natural ones, that are active against the most broaden spectrum of Candida species. Herein, a screening of the antifungal potential of a phenolic extract of Cistus ladanifer from Northeastern Portugal, against Candida species was performed. Furthermore, the extract was characterized by HPLC-DAD-ESI/MS. Phenolic acids and derivatives (3.96 mg/g extract), ellagic acid derivatives (30.34 mg/g extract), and flavonoids (4.15 mg/g extract), such as catechins, flavonols and flavones, were found in the sample. The most abundant group was ellagic acid derivatives in which punicalagin gallate, a derivative of punicalagin attached to gallic acid, was found in highest amount (15.99 ± 0.02 mg/g extract). These compounds (i.e., ellagitannins) could be related to the strong inhibition of C. albicans, C. glabrata and C. parapsilosis growth (MIC < 0.05 mg/ml). Moreover, the best antifungal activity was against C. glabrata, where the studied extract was able to cause at least 3 Log of reduction at concentrations below 0.05 mg/mL and a total growth inhibition at concentrations above 0.625 mg/mL.
- Antifungal activity of phenolic compounds identified in flowers from North Eastern Portugal against Candida speciesPublication . Alves, Carlos Tiago; Ferreira, Isabel C.F.R.; Barros, Lillian; Silva, Sónia; Azeredo, Joana; Oliveira, Rosário; Henriques, MarianaTo evaluate the antifungal effect of gallic acid, catechin, luteolin and quercetin, phenolic compounds identified from flowers of North Eastern Portugal, against Candida planktonic and biofilm cells. Materials & methods: The MICs were determined in Candida planktonic cells and the effect of phenolic compounds on Candida biofilms was assessed through quantification of CFUs. Results: MIC values demonstrated that gallic acid presented the highest effect against all Candida species. Catechin showed a similar effect against Candida albicans American Type Culture Collection (ATCC) 90028 cells. In addition, gallic acid and quercetin had demonstrated only a minimal effect against Candida species biofilms. Conclusion: Gallic acid affected the growth of the different planktonic Candida species in all concentrations used; still, catechin showed a similar effect against C. albicans ATCC 90028 and Candida glabrata ATCC 2001 cells. In addition, only gallic acid and quercetin demonstrated a slight effect against all Candida species biofilms.
- Antimicrobial potential of Eucalyptus globulus against biofilms of Staphylococcus aureus isolated from bovine mastitisPublication . Gomes, Fernanda; Martins, Natália; Ferreira, Isabel C.F.R.; Henriques, MarianaStaphylococcus aureus are among the most common species isolated from bovine mastitis. The pathogenesis of this bacterium is facilitated by a number of virulence factors, including the ability to adhere to abiotic surfaces and/or host tissues often leading to biofilms' formation. From the clinical perspective, the most important feature of Staphytococcus species' biofilms is their high tolerance to the conventional antimicrobial therapy. So, the increasing number of bovine mastitis and the higher levels of Staphylococcus species resistance to traditional antimicrobial agents are considered an important alert for the necessity to focus the future research on identification and development of new strategies to combat S. aureus mastitis. RecenUy, the interest in natural alternatives based on plant extracts has been rising. In add~ion to their health benefits, their antimicrobial potential has been increasingly reported. Taking this into consideration, the evaluation of hydromethanolic extracts of E. globulus against S. aureus biofilms was tested and compared with penicillin, one of the antibiotics most often used in the treatment of cattle infections. All mastitis' isolates tested were good-biofilm producers. As expected penicillin has demonstrated poor activity against S. aureus biofilms (<1 log reduction). However, E. globulus Labill was bactericidal, promoting a biofilm cell reduction of 2-3 log. Therefore, the present work showed the potential antimicrobial activity of E. g/obulus against S. aureus from bovine mastitis, namely in biofilm mode of growth and drew attention to its promising use as an alternative to penicillin.
- Bioactive properties and functional constituents of Hypericum androsaemum L.: A focus on the phenolic profilePublication . Jabeur, Inès; Tobaldini, Flávia; Martins, Natália; Barros, Lillian; Martins, Ivone; Calhelha, Ricardo C.; Henriques, Mariana; Silva, Sónia; Achour, Lotfi; Santos-Buelga, Celestino; Ferreira, Isabel C.F.R.Hypericum androsaemum L. ethanol:water extract acted as a lipid peroxidation inhibitor and free radical scavenger. Amarked inhibition of the growth of breast, lung, cervical and hepatocellular human carcinoma cell lineswas also observed, whereas no toxicity was shown against non-tumor porcine liver cells (N400 μg/mL). The extract was also effective in inhibiting nitric oxide production, as an indicator of the anti-inflammatory potential. The anti-Candida effects varied among different strains of the same species, C. glabrata and C. tropicalis being the most sensible species with an effect directly related with the extract concentrations tested. A significant antibiofilm formation potential was also observed, namely for C. glabrata and C. tropicalis (biofilm reduction N90%). 5-O-Caffeoylquinic and 3-O-caffeoylquinic acids were themost abundant phenolic compounds identified in the extract, and might be related with the observed bioactive effects. Nevertheless, future studies should be carried out to obtain dose-response curves of the isolated active compounds, in order to perform further preclinically testing to quantify the presence of the most active compounds in the extract.
- Candidacidal potential of licorice phenolic extract: emphasis on its mode of actionPublication . Martins, Natália; Costa-Oliveira, Sofia; Ferreira, Isabel C.F.R.; Silva, Sónia; Henriques, MarianaMedicinal plants bave gained a special attention in the last years, due to its renowned health benefits, such as antimicrobial effects [I]. In fact, several natural matrices bave been increasingly studied, namely for its antifungal activity against opportunistic fungi [2,3]. Candida species, although commensa! microorganisms, have caused severe organic dysfunctions to the host, once current antifungal agents have lost their recognized efficiency [2]. So, numerous studies have been carried out focusing the mechanisms of acquired drug-resistance by Candida species [
- Candidiasis: predisposing factors, prevention, diagnosis and alternative treatmentPublication . Martins, Natália; Ferreira, Isabel C.F.R.; Barros, Lillian; Silva, Sónia; Henriques, MarianaCandidiasis is the most common opportunistic yeast infection. Candida species and other microorganisms are involved in this complicated fungal infection, but Candida albicans continues to be the most prevalent. In the past two decades, it has been observed an abnormal overgrowth in the gastrointestinal, urinary and respiratory tracts, not only in immunocompromised patients, but also related to nosocomial infections and even in healthy individuals. There is a widely variety of causal factors that contribute to yeast infection which means that candidiasis is a good example of a multifactorial syndrome. Due to rapid increase in the incidence of these infections, this is the subject of numerous studies. Recently, the focus of attention is the treatment and, above all, the prevention of those complications. The diagnosis of candidiasis could become quite complicated. Prevention is the most effective “treatment”, much more than eradication of the yeast with antifungal agents. There are several aspects to consider in the daily routine that can provide a strength protection. However, a therapeutic approach is necessary when the infection is established and, therefore, other alternatives should be explored. This review provides an overview on predisposition factors, prevention and diagnosis of candidiasis, highlighting alternative approaches for candidiasis treatment.