Browsing by Author "Silva, I. Vieira da"
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- 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.
- 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.