A re-collection of Plakortis quasiamphiaster from Vanuatu in 2003 resulted in the isolation of three known compounds, plakinidine A (1) and amphiasterins B1 (6) and B2 (7). Also isolated was a new bis-oxygenated pyrroloacridine alkaloid, plakinidine E (8), with a unique O-substitution versus N-substitution at position C-12 in 1. The biological evaluation of the active compounds in two assays provided complementary data. Plakinidine A (1) exhibited cytotoxicity against human colon H-116 cells with an IC50 of 0.23 microg/mL, but there were no effects against the yeast Saccharomyces cerevisiae diploid homozygous deletion strain of topoisomerase I (top1Delta). By contrast, 8 was inactive against H-116 cells but was potent in the yeast halo screen.
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http://dx.doi.org/10.1021/np060585w | DOI Listing |
J Org Chem
March 2009
Université de Lyon, Institut de Chimie et de Biochimie Moléculaire et Supramoléculaire, 43 Boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex, France.
The first total synthesis of amphiasterin B4, a secondary metabolite previously isolated from Plakortis quasiamphiaster has been achieved. The core structure has been reached according to a highly stereoselective one-pot epoxidation/cyclization of an unsaturated diol. This substrate can be prepared from beta,gamma-unsaturated diesters readily available from the organocatalyzed protonation of a transient dienol generated by UV irradiation of corresponding alpha,beta-unsaturated isomers.
View Article and Find Full Text PDFJ Nat Prod
January 2007
Department of Chemistry and Biochemistry, Institute of Marine Sciences, University of California, Santa Cruz, California 95064, USA.
A re-collection of Plakortis quasiamphiaster from Vanuatu in 2003 resulted in the isolation of three known compounds, plakinidine A (1) and amphiasterins B1 (6) and B2 (7). Also isolated was a new bis-oxygenated pyrroloacridine alkaloid, plakinidine E (8), with a unique O-substitution versus N-substitution at position C-12 in 1. The biological evaluation of the active compounds in two assays provided complementary data.
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