New flavone from the leaves of Neea theifera (Nyctaginaceae)

Neea theifera Oerst. (Nyctaginaceae) is widely used in Brazilian folk medicine for the treatment of gastric ulcers and inflammation. Phytochemical investigation of the leaves of Neea theifera afforded the isolation of the new flavone luteolin-7-O-[2″-O-(5‴-O-feruloyl)-β-D-apiofuranosyl]- β-D-glucopyranoside (1) besides the eight-known compounds vitexin, isovitexin, isoorientin, orientin, vicenin-2, chrysoeriol, apigenin and luteolin. Their chemical identification was established by NMR spectroscopic methods including 2D-NMR, as well as UV and ESI-MS analyses. ©2007 Sociedade Brasileira de Química.

Potencial alelopático de extratos e frações de Neea theifera Oerst. (Nyctaginaceae) sobre sementes e plântulas de Lactuca sativa

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Uso sustentável da biodiversidade brasileira: prospecção químico-farmacológica em plantas superiores - Neea theifera Oersted (Nyctaginaceae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Mutagenic effect of native species of the Brazilian Cerrado with anti-ulcerogenic activity

Neea theifera Oerted (Nyctaginaceae), Guapira noxia Linn. (Nyctaginaceae) and Hancornia speciosa Gomes (Apocynaceae) are plant species found in Brazilian Cerrado used popularly for the treatment of gastric ulcers. Here they are assessed for mutagenic activity by analysis of the reverse mutations induced in Salmonella typhimurium strains TA100, TA98, TA102 and TA97a, by extracts of the plants, with and without metabolic activation. Methanol and chloroform extracts of N. theifera and G. noxia and methanolic and aqueous extracts of H. speciosa were tested at five different concentrations. It was found that only the methanolic extract of H. speciosa exhibited a positive mutagenic effect, on strains TA98 and TA100 in the absence of metabolic activation. The phytochemical analysis of the species suggested that condensed tannins are the main compounds responsible for the observed effect.

The relationship between leaf nitrogen, nitrogen metabolites and herbivory in two species of Nyctaginaceae from the Brazilian Cerrado

Guapira graciliflora and Neea theifera are taxonomically related species of the tribe Pisoneae. Both species are found in the same environment, the Brazilian Cerrado, and therefore, are subjected to similar selective pressures. These species occur in oligotrophic environments, yet contain high concentrations of nitrogen in their leaves. The present study was carried out to investigate the ecological role of nitrogen in herbivory on these species. The differences in the N content, compositions of secondary N-metabolites, mechanical resistance, and water content between their leaves indicate that these species have different adaptations as defense mechanisms. In both species, their high nitrogen content seems to promote herbivory. The presence of secondary nitrogen metabolites does not prevent the species from suffering intense damage by herbivores on their early leaves. The herbivory rates observed were lower for mature leaves of both species than for young leaves. In G. graciliflora, nutritional content and leaf hardness are the most important variables correlated with reduction of herbivory rates, whereas in N. theifera, N compounds are also correlated with herbivory rates. Despite the differences in the strategies of these two species, they exhibit a similar efficiency of protection against natural enemies because their total herbivory rates are similar. The difference in their N defense allocation may imply benefits for survival under Cerrado conditions. We briefly discuss the oligotrophic habitat conditions of the studied plants and possible advantages of their strategies of N accumulation and metabolic uses. (C) 2011 Elsevier B.V. All rights reserved.

Custos energéticos e econômicos do agroecossistema milho em consórcio com pinhão-manso

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Custos energéticos do agroecossistema pinhão-manso e milho: comparativo entre o sistema de condução sequeiro e o irrigado

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Contribution of woody habitat islands to the conservation of birds and their potential ecosystem services in an extensive Colombian rangeland

The conservation of birds and their habitats is essential to maintain well-functioning ecosystems including human-dominated habitats. In simplified or homogenized landscapes, patches of natural and semi-natural habitat are essential for the survival of plant and animal populations. We compared species composition and diversity of trees and birds between gallery forests, tree islands and hedges in a Colombian savanna landscape to assess how fragmented woody plant communities affect forest bird communities and how differences in habitat characteristics influenced bird species traits and their potential ecosystem function. Bird and tree diversity was higher in forests than in tree islands and hedges. Soil depth influenced woody species distribution, and canopy cover and tree height determined bird species distribution, resulting in plant and bird communities that mainly differed between forest and non-forest habitat. Bird and tree species and traits widely co-varied. Bird species in tree islands and hedges were on average smaller, less specialized to habitat and more tolerant to disturbance than in forest, but dietary differences did not emerge. Despite being less complex and diverse than forests, hedges and tree islands significantly contribute to the conservation of forest biodiversity in the savanna matrix. Forest fragments remain essential for the conservation of forest specialists, but hedges and tree islands facilitate spillover of more tolerant forest birds and their ecological functions such as seed dispersal from forest to the savanna matrix.

Catalanin yhtälön ratkaisut pienillä, parittomilla alkulukupotensseilla

Catalanin konjektuurin mukaan Diofantoksen yhtälön xp-yq=1, missä p,q ≥2, ainoat nollasta eroavat ratkaisut ovat (x,y,p,q)=(±3,2,2,3). Yhtälöä xp-yq=1 kutsutaan Catalanin yhtälöksi. Konjektuuri on yritetty todistaa oikeaksi 1800-luvulta lähtien, mutta saatiin lopulta todistettua oikeaksi 2000-luvun alussa Preda Mihăilescun todistuksen myötä. Mihăilescun todistus perustuu ympyräkuntien käyttöön ja Galois’n moduleihin. Tässä tutkielmassa esitetään yksi Catalanin konjektuurin ratkaisua helpottava tulos. Tutkielmassa esitetään Mihăilescun todistus väitteelle, ettei yhtälöllä xp-yq=1 ole nollasta eroavia ratkaisuja, kun p ja q ovat parittomia alkulukuja ja vähintään toinen niistä on pienempi kuin 43. Todistus perustuu, Mihăilescun todistusten mukaisesti, ympyräkuntien käyttöön. Tutkielman lopussa kerrotaan, miten todistettua aputulosta voi käyttää apuna Catalanin konjektuurin ratkaisemisessa.

Catalanin yhtälön ratkaisut pienillä, parittomilla alkulukupotensseilla

Catalanin konjektuurin mukaan Diofantoksen yhtälön xp-yq=1, missä p,q ≥2, ainoat nollasta eroavat ratkaisut ovat (x,y,p,q)=(±3,2,2,3). Yhtälöä xp-yq=1 kutsutaan Catalanin yhtälöksi. Konjektuuri on yritetty todistaa oikeaksi 1800-luvulta lähtien, mutta saatiin lopulta todistettua oikeaksi 2000-luvun alussa Preda Mihăilescun todistuksen myötä. Mihăilescun todistus perustuu ympyräkuntien käyttöön ja Galois’n moduleihin. Tässä tutkielmassa esitetään yksi Catalanin konjektuurin ratkaisua helpottava tulos. Tutkielmassa esitetään Mihăilescun todistus väitteelle, ettei yhtälöllä xp-yq=1 ole nollasta eroavia ratkaisuja, kun p ja q ovat parittomia alkulukuja ja vähintään toinen niistä on pienempi kuin 43. Todistus perustuu, Mihăilescun todistusten mukaisesti, ympyräkuntien käyttöön. Tutkielman lopussa kerrotaan, miten todistettua aputulosta voi käyttää apuna Catalanin konjektuurin ratkaisemisessa.