Jorge Paiva

Chemotaxonomic study on Thymus villosus from Portugal

The composition of the essential oils of four populations of Thymus villosus subsp. lusitanicus (Boiss.) Coutinho from Portugal was investigated by GC and GC-MS. To study the chemical polymorphism the results obtained from GC analyses of the volatile oils from individual plants from four populations were submited to Principal Component and Cluster analyses. A comparision with the essential oil of T. villosus subsp. villosus, previously studied by us was done. Important differences with regard to the major constituents in these two taxa were found. Linalool, geranyl acetate, geraniol and terpinen-4-ol were the main components of the essential oils of T. villosus subsp. lusitanicus, whereas in the oil of T. villosus subsp. villosus p-cymene, myrcene and alpha-terpineol were the major ones. Although, both taxa showed chemical polymorphism, different types of essential oils were characterized in each one: linalool; linalool/ terpinen-4-ol/trans-sabinene hydrate; linalool/1,8-cineole; geranyl acetate/geraniol; geranyl acetate/geraniol/1,8-cineole in T. villosus subsp. lusitanicus and p-cymene/camphor/linalool; p-cymene/borneol; linalool/geraniol/geranyl acetate; alpha-terpineol/camphor/myrcene in T. villosus subsp. villosus. Thus, the two subspecies of T. villosus can be easely differenciated by the composition of their essential oils.

Essential oil composition and variability of Thymus lotocephalus and Thymus × mourae.

Abstract The composition of the essential oils of four populations of Thymus lotocephalus G. Lopez and R. Morales and one population of T.×mourae Paiva and Salgueiro, two endemic taxa from Portugal, was investigated mainly by GC and GC–MS. T×mourae is a natural hybrid between T. lotocephalus and T. mastichina (L.) L. subsp. donyanae R. Morales, which essential oil was analysed for the first time. In its oil, it was possible to find compounds of both parents, which could enable us to confirm its intermediate status between those two taxa. 1,8-Cineole and borneol were the main constituents in the essential oil of T.×mourae, whereas linalool, geranyl acetate and 1,8-cineol were the major ones in T. lotocephalus. Intermedeol was also an important constituent in the oils of both taxa. Nevertheless, the volatile oils of the four populations investigated of T. lotocephalus showed important differences among the main constituents. In order to study their infraspecific variability, the results obtained in the analysis of individual plants were submitted to a Principal Component and Chemometric Cluster Analyses. Five types of essential oils were found: linalool, 1,8-cineole, linalool/1,8-cineole, linalyl acetate/linalool and geranyl acetate.

Screening and identification of neuroprotective compounds relevant to Alzheimer's disease from medicinal plants of S. Tomé e Príncipe

ETHNOPHARMACOLOGICAL RELEVANCE Alzheimer׳s disease (AD) neuropathology is strongly associated with the activation of inflammatory pathways, and long-term use of anti-inflammatory drugs reduces the risk of developing the disease. In S. Tomé e Príncipe (STP), several medicinal plants are used both for their positive effects in the nervous system (treatment of mental disorders, analgesics) and their anti-inflammatory properties. The goal of this study was to determine whether a phenotypic, cell-based screening approach can be applied to selected plants from STP (Voacanga africana, Tarenna nitiduloides, Sacosperma paniculatum, Psychotria principensis, Psychotria subobliqua) in order to identify natural compounds with multiple biological activities of interest for AD therapeutics. MATERIALS AND METHODS Plant hydroethanolic extracts were prepared and tested in a panel of phenotypic screening assays that reflect multiple neurotoxicity pathways relevant to AD-oxytosis in hippocampal nerve cells, in vitro ischemia, intracellular amyloid toxicity, inhibition of microglial inflammation and nerve cell differentiation. HPLC fractions from the extract that performed the best in all of the assays were tested in the oxytosis assay, our primary screen, and the most protective fraction was analyzed by mass spectrometry. The predominant compound was purified, its identity confirmed by ESI mass spectrometry and NMR, and then tested in all of the screening assays to determine its efficacy. RESULTS An extract from the bark of Voacanga africana was more protective than any other plant extract in all of the assays (EC50s≤2.4 µg/mL). The HPLC fraction from the extract that was most protective against oxytosis contained the alkaloid voacamine (MW=704.90) as the predominant compound. Purified voacamine was very protective at low doses in all of the assays (EC50s≤3.4 µM). CONCLUSION These findings validate the use of our phenotypic screening, cell-based assays to identify potential compounds to treat AD from plant extracts with ethnopharmacological relevance. Our study identifies the alkaloid voacamine as a major compound in Voacanga africana with potent neuroprotective activities in these assays.

Pollen morphology of Chamaebuxus (DC.) Schb., Chodatia Paiva and Rhinotropis (Blake) Paiva (Polygala L., Polygalaceae)

Abstract Polygala L. is a large and highly diverse genus with complex taxonomy, but pollen morphological information for this taxon is scarce. In the present study, pollen characters have been used to assess the taxonomic delimitation and phylogenetic relationships of three newly established subgenera of Polygala: Chamaebuxus, Chodatia and Rhinotropis (sensu Paiva). The pollen morphology of 22 species has been examined using light microscopy and scanning electron microscopy of acetolysed material. The pollen of 15 of the species is examined for the first time. The pollen grains are isopolar, radially symmetrical, tectate and, typically, polyzonocolporate with numerous colpi running parallel to the polar axis, and an endocingulum around the equator. Two pollen types can be distinguished: Type I, which includes species belonging to Rhinotropis, and Type II, which includes species from Chamaebuxus and Chodatia. The two pollen types are described and the pollen of the three studied subgenera is illustrated. Despite the low infrageneric morphological diversity observed within the genus Polygala, quantitative characters of pollen grains support the current classification of the subgenera Chamaebuxus, Chodatia and Rhinotropis, and reveal a closer relationship between the first two taxa. Pollen characters are shown to be a useful and informative tool for assessing taxonomic position and phylogenetic relationships within Polygalaceae, especially at higher taxonomic levels.

Revisión de la distribución geográfica y la ecología de tres especies de Arabis L., en Portugal continental.

SILvEIRA. P., PAiv~, J. & MARCOS SAMANIEGo, N. 2000. Revision de la distribucion geografica y la ecologia de tres especies de Aiabis L. en Portugal continental. Bat. Comp/utensjs 24: 65-73. Se ha estudiado la corologia y ecologia de Aiabisjaressi Rothm., Atabis sadine (Samp.) Cout. y A jo bis stenoc-ai-po Eoiss. & Reut. en Portugal continental. Basandonos en la revision de material de herbario y citas bibliograficas, se proponen para las tres especies 41 nuevas coordenadas UTM y se excluyen 4, resultando una nueva lista que incluye 56 coordenadas.

Conservation of Biological Resources: Why Does It Matter?

The world population has grown from 2500 million people in the year 1950 to more than 7300 million people in the year 2015, posing a challenge never faced before in human history. People are less aware about the limitedness of natural resources and the consequences of the present development. Increased population, associated with technological advancement undermines the sustainable development of any nation. Daily, many species are going extinct due to the continuous fragmentation/destruction of habitats, many of which have not been studied or referenced. Presently, we are living in the «Decade of Biodiversity» from the period of year 2011 to the year 2020, which was launched at the end of the year 2011 by the General Secretary of the United Nations, Ban Ki-moon. This poses a great challenge and all societies and nations are saddled with the responsibility of revising their actual models of economic development and increasing their knowledge base, by planning more intelligent and integrative programmes for the conservation of our biological resources and its functions in the ecosystems and human health. This chapter aims to raise awareness on the relevance of biodiversity in people’s life. It emphasizes subjects, such as the importance of forests, the unknown biodiversity, and the extinction of species, in order to alert the general public, students, teachers, and other stakeholders to the importance of all biological resources.

Polygala kalaboensis (Polygalaceae), a new species from Zambia

SummaryPolygala kalaboensis Paiva, a new species from Zambia is described and illustrated. It belongs to the subgenus Polygala, section Tetrasepalae and subsection Hexandriae, a subsection with sixteen species from Tropical Africa and two from Madagascar.

Typification of two Linnaean names in Polygala (Polygalaceae) : P. bracteolata and P. myrtifolia

Two Linnaean names of Polygala, P. bracteolata and P. myrtifolia, are lectotypified.

Sobre quatro taxa pouco frequentes da flora portuguesa

Assinalam-se 4 taxa relevantes (com estatuto de proteccao), que ocorrem na Serra do Caramulo, situada nas provincias de Beira Alta e Beira Litoral, em Portugal. Destaca-se o endemismo iberico Narcissus confusus Pugsley.

Contribuçao para o conhecimiento da flora vascular da serra do Açor (Portugal)

SILVEIRA, P. C., PAIvA, 1. A. R. & MARcos SAMANIEGO, N. 1998. Contribution to the knowledge of the vascular flora of Serrado A~or (Portugal). flor Complutensis 22: 145-151. Fifteen taxa with chorological interest are reponed from Sena do A 9or, situated between ihe provinces Beira Alta, Bejin Litoral ano Bejin Baixa in Portugal. The most interesting records include Ervsimum lagascae Rivas Goday & Bellot, Festuca summilusitana Franco & Rocha Afonso, Saxifraga fragosol Sennen and Fryngium duriar Gay ex Boiss.