RESUMO
Tibet's ancient topography and its role in climatic and biotic evolution remain speculative due to a paucity of quantitative surface-height measurements through time and space, and sparse fossil records. However, newly discovered fossils from a present elevation of â¼4,850 m in central Tibet improve substantially our knowledge of the ancient Tibetan environment. The 70 plant fossil taxa so far recovered include the first occurrences of several modern Asian lineages and represent a Middle Eocene (â¼47 Mya) humid subtropical ecosystem. The fossils not only record the diverse composition of the ancient Tibetan biota, but also allow us to constrain the Middle Eocene land surface height in central Tibet to â¼1,500 ± 900 m, and quantify the prevailing thermal and hydrological regime. This "Shangri-La"-like ecosystem experienced monsoon seasonality with a mean annual temperature of â¼19 °C, and frosts were rare. It contained few Gondwanan taxa, yet was compositionally similar to contemporaneous floras in both North America and Europe. Our discovery quantifies a key part of Tibetan Paleogene topography and climate, and highlights the importance of Tibet in regard to the origin of modern Asian plant species and the evolution of global biodiversity.
RESUMO
A new furostanol saponin, (25S)-26-O-ß-D-glucopyranosyl-5ß-furost-20(22)-en-3ß, 15ß,26-triol-3-O-[α-L-rhamnopyranosyl-(1-4)]-ß-D: -glucopyranoside, namely, aspacochioside D (1) were isolated from Asparagus cochinchinensis (Lour.) Merr, along with three known saponins, aspacochioside C (2), (25S)-5ß-spirostan-3ß-yl-O-[O-α-L-rhamnopyranosyl-(1-4)]-ß-D-glucopyranoside (3), and pseudoprotoneodioscin (4). The structure of 1 was elucidated on the basis of chemical reactions and spectral analysis (IR, GC, ESI-MS, (1)H-NMR, (13)C-NMR, DEPT, HMBC, HMQC and NOESY). The antiproliferative effects of 1-4 were evaluated in a cytotoxicity assay against the human tumor cell line, A549. Compound 2 (Aspacochioside C) exhibited moderate cytotoxicity against A-549, with an IC(50) value of 3.87 µg/mL.
Assuntos
Antineoplásicos Fitogênicos/química , Asparagus/química , Saponinas/química , Antineoplásicos Fitogênicos/isolamento & purificação , Antineoplásicos Fitogênicos/farmacologia , Linhagem Celular Tumoral , Cromatografia Gasosa , Corantes , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Hidrólise , Espectroscopia de Ressonância Magnética , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Raízes de Plantas/química , Saponinas/isolamento & purificação , Saponinas/farmacologia , Espectrometria de Massas por Ionização por Electrospray , Espectrofotometria Infravermelho , Esteroides/química , Esteroides/isolamento & purificação , Esteroides/farmacologia , Sais de Tetrazólio , TiazóisRESUMO
Seven lignans having a diarylhydroxybutyrolactone skeleton were isolated from the leaves and stems of Trachelospermum jasminoides (Lindl.) Lem. Their structures were elucidated to be nortrachelogenin 8' -O-beta-D-glucopyranoside (1), nortrachelogenin 5'- C- beta-D-glucopyranoside (2), trachelogenin amide (3), nortracheloside, trachelogenin, tracheloside, and trachelogenin 4'- O- beta-gentiobioside, respectively, on the basis of spectroscopic analyses. Lignans 1 - 3 were structurally identified to be new compounds, and 2 was a rare C-glucosyl-lignan.
Assuntos
Apocynaceae , Fitoterapia , Extratos Vegetais/química , Humanos , Lignanas/química , Folhas de Planta , Caules de PlantaRESUMO
OBJECTIVE: To study the chemical constituents of Ervatamia hainanensis. METHOD: The compounds were separated and purified by column chromatography with silica gel, and identified by IR, MS, NMR and 2D-NMR. RESULT: Five compounds were identified as I (isolariciresinol 9-O-beta-D-glucopyranoside), II (cycloartenol), III (beta-amyrin acetate), IV (beta-sitosterol), V (daucosterol), respectively. CONCLUSION: All the compounds were isolated from this plant for the first time.