Isolation and structure elucidation of cytotoxic polyacetylenes and polyenes from Echinacea pallida

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• 作者：Federica Pellati ; Samuele Calò ; Stefania Benvenuti ; Barbara Adinolfi ; Paola Nieri and Michele Melegari
• 关键词：Echinacea pallida ; Asteraceae ; Structure elucidation ; Cytotoxicity ; Polyacetylenes ; Polyenes
• 刊名：Phytochemistry
• 出版年：2006
• 出版时间：July 2006
• 年：2006
• 卷：67
• 期：13
• 页码：1359-1364
• 全文大小：126 K

文摘

Bioassay-guided fractionation of n-hexane extracts of Echinacea pallida (Asteraceae) roots led to the isolation and structure elucidation of two polyacetylenes (1, 3) and three polyenes (2, 4, 5). Two are known hydroxylated compounds, namely 8-hydroxy-pentadeca-(9E)-ene-11,13-diyn-2-one (1) and 8-hydroxy-pentadeca-(9E,13Z)-dien-11-yn-2-one (2). Two dicarbonylic constituents, namely pentadeca-(9E)-ene-11,13-diyne-2,8-dione (3) and pentadeca-(9E,13Z)-dien-11-yne-2,8-dione (4), were isolated and characterized for the first time. Furthermore, the structure elucidation of pentadeca-(8Z,13Z)-dien-11-yn-2-one (5) is described. The structure of the compounds isolated was determined on the basis of UV, IR, NMR (including 1D and 2D NMR experiments, such as ¹H–¹H gCOSY, gHSQC-DEPT, gHMBC, gNOESY) and MS spectroscopic data. The cytotoxic activity of the isolated constituents against MIA PaCa-2 human pancreatic adenocarcinoma cells was evaluated in the concentration range 1–100 μg/ml. Results show that the hydroxylated compounds (1, 2) have low cytotoxicity, while the more hydrophobic polyacetylenes (3) and polyenes (4, 5) displayed moderate activity.