Isolation and structure elucidation of cytotoxic polyacetylenes and polyenes from Echinacea pallida.
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 microg/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.
Pellati
Federica
F
Department of Pharmaceutical Sciences, University of Modena and Reggio Emilia, Via G. Campi 183, 41100 Modena, Italy. pellati.federica@unimore.it
Calò
Samuele
S
Benvenuti
Stefania
S
Adinolfi
Barbara
B
Nieri
Paola
P
Melegari
Michele
M
D000114:Acetylene / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D020900:Echinacea / Q000737:chemistry*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011090:Polyenes / Q000737:chemistry* / Q000302:isolation & purification / Q000633:toxicity*; D011108:Polymers / Q000737:chemistry* / Q000302:isolation & purification / Q000633:toxicity*; D053279:Polyynes; D013329:Structure-Activity Relationship
D011090:Polyenes; D011108:Polymers; D053279:Polyynes; D000114:Acetylene