Browsing by Author "Nogueira, Teresa"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
- New reports on secretory structures of vegetative and floral organs of Hypericum elodes (Hypericaceae)Publication . Silva, I. Vieira da; Nogueira, Teresa; Ascensão, LiaHypericum elodes L. (Hypericaceae), commonly known as marsh St. John’s wort, is one of the fourteen species found spontaneously in Portugal and it is endemic of Europe. It occurs in acidic waterlogged grounds in the Norwest of Portugal and in the Azores islands, Pico and São Miguel [1]. In the last decades intense phytochemical and pharmacological research have been performed in Hypericum species, namely in H. perforatum, the most studied species of the genus and traditionally used as a medicinal plant. Its bioactive secondary metabolites, naphtodianthrones (e.g. hypericin and pseudohypericin), phloroglucinols (e.g. hyperforin), bioflavonoids and xanthones have been widely studied for their anti-depressant, anti-microbial, anti-viral and anti-proliferative properties [2]. Despite the abundant phytochemical reports available in Hypericum species, the morpho-anatomical studies are scarce and fragmented [3-6]. The present study, included in an ongoing project on Hypericum glands, aims to provide new data on the morphology and anatomy of the secretory structures of H. elodes. Although these glands were previously studied in specimens grown in Italy [5], in the current study we describe in detail their morphology, distribution and histochemistry on the vegetative and floral organs. Small branches of H. elodes were collected from populations occurring in Portugal and samples of leaves and flowers, at different stages of development, were fixed with glutaraldehyde and prepared for scanning electron microscopy or embedding in Leica Historesin®, following standard methods. Additionally, the main classes of compounds present in the secretion were histochemically characterized.
- Profile of antimicrobial potential of fifteen Hypericum species from PortugalPublication . Nogueira, Teresa; Medeiros, Maria Augusta; Curto, Maria João Marcelo; Garcia-Pérez, B. E.; Luna-Herrera, J.; Costa, Maria do CéuThe aim of the present study was the search for the industrial exploitation potential of 15 Hypericum species crops from Portugal. Although Hypericum perforatum is well known worldwide, scarce studies have been published of Hypericum spp. identified in Portugal. Extracts from 15 Hypericum species were screened for its antimicrobial activities against 2 Gram- and 2 Gram+ bacteria, 4 non-tuberculous Mycobacterium species, a reference strain H37Rv and 4 drug-resistant strains of Mycobacterium tuberculosis, as well as 4 drug-resistant clinical isolates. In terms of Gram – standards, H. humifusum and H. elodes were the most active against Agrobacterium tumefasciens, with MIC of 2.5 µg/mL. H. elodes and H. hircinum subsp. majus extracts were the most active against MDR-TB strains and isolates, with MIC of 25–100 µg/mL and both exhibited significant effect against MDR-TB clinical isolates. With the exception of H. androsaemum and H. linarifolium all Hypericum species were active against Staphylococcus aureus, the H. perfoliatum and H. elodes at the level of 6 and 12 µg/mL, respectively, and none showed activity on E. coli. Reference compounds isolated from H. perforatum were also tested and might contribute to the activities observed. The profile of the 15 Hypericum spp. as effective antimicrobial therapy against multidrug resistant pathogens is now available, providing scientific validation on a few available ethnopharmacological data resources. This study may be a starting point for the research on the role of various Hypericum species in integrative medicine for infection control of S. aureus and MDR-MTB. Hypericum species may also constitute a source of new leads towards the discovery of either new candidates and biologically active compounds for pharmaceutical interest, for the treatment of multidrug resistant diseases.
- Requisitos de qualidade em óleos essenciais : a importância das monografias da Farmacopeia Europeia e das normas ISOPublication . Martins, Ana Paula; Nogueira, Teresa; Costa, Maria do Céu; Salgueiro, LígiaOs óleos essenciais são produtos naturais utilizados por diversas indústrias, entre as quais se destacam a indústria alimentar e a indústria farmacêutica. Devido à variabilidade inerente a todos os produtos naturais e também aos crescentes problemas de adulterações, este artigo tem por objectivo divulgar e chamar a atenção da importância das normas internacionais existentes, nomeadamente das monografias da Farmacopeia Europeia e das normas ISO, fazendo simultaneamente uma comparação dos principais requisitos nelas estabelecidos. Só o cumprimento dos requisitos de qualidade e segurança adoptados por este tipo de normas pode garantir que os óleos essenciais utilizados para as mais diversas aplicações tenham a qualidade desejável para o fim a que se destinam e não coloquem problemas de segurança.
- Secretory structures on the flowers of Hypericum Pubescens and H. TomentosumPublication . Silva, I. Vieira da; Nogueira, Teresa; Ascensão, LiaHypericum L. (Hypericaceae) is a genus represented by ca. 484 species, shrubs, perennial and annual herbs, growing widely in warm-temperate areas in Europe, West Asia and America [1]. H. perforatum (St. John’s wort), the most representative member of the genus has been used in folk medicine since Antiquity, and nowadays other Hypericum species have been incorporated in traditional medicine systems of several countries around the world. It is now well known that hypericin, pseudohypericin and hyperforin are the main compounds responsible for their therapeutic properties [2]. Although a large number of studies deal with the phytochemical and pharmacological characteristics of Hypericum species, the secretory structures that produce the bioactive compounds have only been examined in detail in a few species [3, 4, 5, 6]. Within the framework of a wider project on Hypericum glands, we have undertaken cytological studies on the flowers of H. pubescens and H. tomentosum. Here we describe the structure, development and distribution pattern of the glands present in these two Hypericum species. Flowers at different stages of development were collected from natural populations of H. pubescens and H. tomentosum, occurring in Portugal. Samples fixed with glutaraldehyde were prepared for scanning electron microscopy or embedding in Leica Historesin® for anatomy, following standard methods.