RESUMO
Tropical montane cloud forests (TMCFs) depend on predictable, frequent, and prolonged immersion in cloud. Clearing upwind lowland forest alters surface energy budgets in ways that influence dry season cloud fields and thus the TMCF environment. Landsat and Geostationary Operational Environmental Satellite imagery show that deforested areas of Costa Rica's Caribbean lowlands remain relatively cloud-free when forested regions have well-developed dry season cumulus cloud fields. Further, regional atmospheric simulations show that cloud base heights are higher over pasture than over tropical forest areas under reasonable dry season conditions. These results suggest that land use in tropical lowlands has serious impacts on ecosystems in adjacent mountains.
Assuntos
Atmosfera , Conservação dos Recursos Naturais , Ecossistema , Árvores , Clima Tropical , Altitude , Animais , Costa Rica , Umidade , Estações do AnoRESUMO
A phytochemical investigation of the chloroform leaf extract of Alchornea latifolia has been undertaken. Along with the triterpenoids taraxerone, friedelin, epifriedelinol, and taraxerol, the plant also contains seco-3,4-friedelin (dihydroputranjivic acid) (1) and seco-3,4-taraxerone (2). These A-ring-opened triterpenoids show in vitro cytotoxic activity against Hep-G2 and A-431 human cancer cell lines and are potent inhibitors of topoisomerase II.
Assuntos
Euphorbiaceae , Ácido Oleanólico/análogos & derivados , Ácido Oleanólico/farmacologia , Plantas Medicinais , Triterpenos/farmacologia , Humanos , Medicinas Tradicionais Africanas , Testes de Sensibilidade Microbiana , Ácido Oleanólico/química , Fitoterapia , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Folhas de Planta , Staphylococcus aureus/efeitos dos fármacos , Streptococcus pneumoniae/efeitos dos fármacos , Triterpenos/química , Células Tumorais Cultivadas/efeitos dos fármacosRESUMO
The crude ethanol extract from the leaves of Dendropanax cf. querceti (Araliaceae) from Monteverde, Costa Rica, exhibits cytotoxic activity against Hep-G2, A-431, and H-4IIE tumor cell lines. The active component has been isolated by activity-directed separation and identified by 1H- and 13C-NMR spectroscopy as the triterpene lupeol. The mechanism of cytotoxic activity of lupeol has been determined to be inhibition of topoisomerase II.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Extratos Vegetais/farmacologia , Folhas de Planta/química , Triterpenos/farmacologia , Animais , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/isolamento & purificação , Humanos , Triterpenos Pentacíclicos , Plantas Medicinais/química , Ratos , Triterpenos/química , Triterpenos/isolamento & purificação , Células Tumorais CultivadasRESUMO
The crude ethanol extract from the leaves of Dendropanax arboreus (Araliaceae) from Monteverde, Costa Rica, exhibits cytotoxic activity against Hep-G2, A-431, H-4IIE, and L-1210 tumor cell lines, but is not toxic against normal hepatocytes. The active component has been isolated by activity-directed separation and identified by 1H- and 13C-NMR spectroscopy as the acetylenic compound cis-1,9,16-heptadecatriene-4,6-diyne-3,8-diol.
Assuntos
Alcinos/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Álcoois Graxos/farmacologia , Panax/química , Plantas Medicinais , Alcinos/química , Alcinos/isolamento & purificação , Animais , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/isolamento & purificação , Células Cultivadas , Di-Inos , Ensaios de Seleção de Medicamentos Antitumorais , Álcoois Graxos/química , Álcoois Graxos/isolamento & purificação , Humanos , Fígado/citologia , Fígado/efeitos dos fármacos , Camundongos , Ratos , Células Tumorais CultivadasRESUMO
The crude ethanol extract from the leaves of Tovomitopsis psychotriifolia (Clusiaceae) exhibits antibacterial activity against Bacillus cereus, Staphylococcus aureus, and Pseudomonas aeruginosa. The biologically active agent in the extract has been isolated by chromatographic techniques and identified by NMR spectroscopy as trans-delta-tocotrienoloic acid.
