Leishmanicidal Activity of (+)-Phyllanthidine and the Phytochemical Profile of Margaritaria nobilis (Phyllanthaceae)

The effects of the Securinega alkaloid (+)-phyllanthidine on Leishmania (L.) amazonensis and the first chemical investigation of Margaritaria nobilis L.f. (Phyllanthaceae) are described. Treating the parasites with this alkaloid caused a dose-dependent reduction in promastigote growth of 67.68% (IC50 82.37 μg/mL or 353 µM) and in amastigote growth of 83.96% (IC50 49.11 μg/mL or 210 µM), together with ultrastructural alterations in the promastigotes. No cytotoxic effect was detected in mammalian cells (CC50 1727.48 µg/mL or CC50 5268 µM). Classical chromatographic techniques and spectral methods led to the isolation and identification of betulinic acid, kaempferol, corilagin, gallic acid and its methyl ester, besides (+)-phyllanthidine from M. nobilis leaves and stems. Margaritaria nobilis is another source of the small group of Securinega alkaloids, together with other Phyllanthaceae (Euphorbiaceae s.l.) species. The low toxicity to macrophages and the effects against promastigotes and amastigotes are suggestive that (+)-phyllanthidine could be a promising antileishmanial agent for treating cutaneous leishmaniasis

Chemical characterisation of the constituents of Eugenia protenta McVaugh and leishmanicidal activity of dimethylxanthoxylin

Universidade Federal do Pará. Instituto de Ciências Exatas e Naturais. Programa de Pós-Graduação em Química. Belém, PA, Brazil.Universidade Federal do Pará. Instituto de Ciências Exatas e Naturais. Programa de Pós-Graduação em Química. Belém, PA, Brazil / Museu Paraense Emílio Goeldi. Coordenação de Botânica. Programa de Capacitação Institucional. Belém, PA, Brazil.Universidade Federal do Pará. Laboratório de Protozoologia e Biologia Estrutural. Belém, PA, Brazil / Universidade Federal do Rio de Janeiro. Instituto de Ciência e Tecnologia em Biologia Estrutural e Bioimagem. Rio de Janeiro, RJ, Brazil.Universidade Federal do Pará. Instituto de Ciências Exatas e Naturais. Programa de Pós-Graduação em Química. Belém, PA, Brazil.Universidade Federal do Pará. Laboratório de Protozoologia e Biologia Estrutural. Belém, PA, Brazil / Universidade Federal do Rio de Janeiro. Instituto de Ciência e Tecnologia em Biologia Estrutural e Bioimagem. Rio de Janeiro, RJ, Brazil.Museu Paraense Emílio Goeldi. Belém, PA, Brazil.Universidade Federal do Pará. Instituto de Ciências Exatas e Naturais. Programa de Pós-Graduação em Química. Belém, PA, Brazil / Museu Paraense Emílio Goeldi. Belém, PA, Brazil.Universidade Federal do Rio de Janeiro. Instituto de Ciência e Tecnologia em Biologia Estrutural e Bioimagem. Rio de Janeiro, RJ, Brazil / Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Laboratório de Microscopia Eletrônica. Belém, PA, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Laboratório de Microscopia Eletrônica. Belém, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Laboratório de Microscopia Eletrônica. Belém, PA, Brasil.The chemical study of Eugenia protenta McVaugh extracts performed by classical and high-performance liquid chromatography techniques and spectral methods has led to the identification of known triterpenoids, flavonoids and an acetophenone derivative (dimethylxanthoxylin). The effect of dimethylxanthoxylin on Leishmania (Leishmania) amazonensis was evaluated against the promastigotes forms after 96 h of treatment. Dimethylxanthoxylin reduced 57 and 59% of the promastigotes growth when treated with 50 and 100 μg/mL solutions, respectively (IC50 117.35 μg/mL or 52.3 μM). Cytotoxicity experiments using MTT assays showed that this substance did not promote cell death after 24 h of treatment. Dimethylxanthoxylin was active on the promastigotes and could be a promising agent for treating leishmaniasis

Long-Term Changes in Concentration and Yield of Riverine Dissolved Silicon From the Poles to the Tropics

Abstract Riverine exports of silicon (Si) influence global carbon cycling through the growth of marine diatoms, which account for ∼25% of global primary production. Climate change will likely alter river Si exports in biome-specific ways due to interacting shifts in chemical weathering rates, hydrologic connectivity, and metabolic processes in aquatic and terrestrial systems. Nonetheless, factors driving long-term changes in Si exports remain unexplored at local, regional, and global scales. We evaluated how concentrations and yields of dissolved Si (DSi) changed over the last several decades of rapid climate warming using long-term data sets from 60 rivers and streams spanning the globe (e.g., Antarctic, tropical, temperate, boreal, alpine, Arctic systems). We show that widespread changes in river DSi concentration and yield have occurred, with the most substantial shifts occurring in alpine and polar regions. The magnitude and direction of trends varied within and among biomes, were most strongly associated with differences in land cover, and were often independent of changes in river discharge. These findings indicate that there are likely diverse mechanisms driving change in river Si biogeochemistry that span the land-water interface, which may include glacial melt, changes in terrestrial vegetation, and river productivity. Finally, trends were often stronger in months outside of the growing season, particularly in temperate and boreal systems, demonstrating a potentially important role of shifting seasonality for the flux of Si from rivers. Our results have implications for the timing and magnitude of silica processing in rivers and its delivery to global oceans.ISSN:0886-6236ISSN:1944-922