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Description of a strain from an atypical population of Aspergillus parasiticus that produces aflatoxins B only, and the impact of temperature on fungal growth and mycotoxin production

Publication . Arita, Camila; Calado, Thalita; Venâncio, Armando; Lima, Nelson; Rodrigues, Paula

In this study, an atypical strain of Aspergillus parasiticus is described. This strain, reported from Portuguese almonds, was named Aspergillus parasiticus B strain. The strain is herein characterised at the morphological and physiological levels, and compared with the typical A. parasiticus strain and other similar species in section Flavi. Previously published morphological and molecular data support that the B strain is very closely related to the A. parasiticus type strain. However, while A. parasiticus typically produces aflatoxins B and G, B strain produces aflatoxins B only. Furthermore, this atypical strain showed to differ from the typical strain in the fact that higher growth (colony diameter) and aflatoxin B1 production were observed at 25 ºC than at 30 ºC, whereas the opposite was observed for the typical strain. This strain can become a major food safety concern in colder regions where the typical A. parasiticus strains are not well adapted.

2014Journal article

Restricted access

Plants used in folk medicine: the potential of their hydromethanolic extracts against Candida species

Publication . Martins, Natália; Ferreira, Isabel C.F.R.; Barros, Lillian; Carvalho, Ana Maria; Henriques, Mariana; Silva, Sónia

Currently, opportunistic fungal infections are considered a serious problem regarding public health. Despite the advances towards the synthesis of new antifungal agents, an increasing incidence of drug-resistant microorganisms has been observed. In this sense, other alternatives are necessary. In the present work, the antifungal activity of extracts from ten different plants, commonly used in folk medicine, were evaluated against nineteen Candida strains, including C. albicans, C. glabrata, C. parapsilosis and C. tropicalis species. Although the majority of the extracts had no antimicrobial effect, Juglans regia extract was very effective, exerting an inhibitory effect against all the tested Candida strains, while Eucalyptus globulus was effective against seventeen of them. Pterospartum tridentatum and Rubus ulmifolius presented similar antifungal effects, being effective against six Candida strains. The diameter of halo ranged, respectively, between 9-14 mm and 9-21 mm to the mentioned plant extracts, and the MIC50 values evidenced mainly a fungistatic activity. Both extracts showed similar MIC50 values for C. albicans strains, while C. parapsilosis and C. glabrata were more sensible to E. globulus. Otherwise, all the C. tropicalis strains were more sensible to J. regia. Overall, hydromethanolic plant extracts could constitute promissory alternatives to the traditional antifungal agents.

2015Journal article

Open access

Antibacterial potential of Northeastern Portugal wild plant extracts and respective phenolic compounds

Publication . Pinho, Eva; Ferreira, Isabel C.F.R.; Barros, Lillian; Carvalho, Ana Maria; Soares, Graça; Henriques, Mariana

The 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.

2014Journal article

Open access

Activity of phenolic compounds from plant origin against Candida species

Publication . 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.

2015Journal article

Open access

Evaluation of bioactive properties and phenolic compounds in different extracts prepared from Salvia officinalis L.

Publication . Martins, Natália; Barros, Lillian; Santos-Buelga, Celestino; Henriques, Mariana; Silva, Sónia; Ferreira, Isabel C.F.R.

The therapeutic benefits of medicinal plants are well known. Nevertheless, essential oils have been the main focus of antioxidant and antimicrobial studies, remaining scarce the reports with hydrophilic extracts. Thus, the antioxidant and antifungal activities of aqueous (prepared by infusion and decoction) and methanol/water (80:20, v/v) extracts of sage (Salvia officinalis L.) were evaluated and characterized in terms of phenolic compounds. Decoction and methanol/water extract gave the most pronounced antioxidant and antifungal properties, being positively related with their phenolic composition. The highest concentration of phenolic compounds was observed in the decoction, followed by methanol/water extract and infusion. Fungicidal and/or fungi static effects proved to be dependent on the extracts concentration. Overall, the incorporation of sage decoction in the daily diet or its use as a complement for antifungal therapies, could provide considerable benefits, also being an alternative to sage essential oils that can display some toxic effects.

2015Journal article

Open access