Antimalarial β-Carbolines from the New Zealand Ascidian <i>Pseudodistoma opacum</i>
作者:Susanna T. S. Chan、A. Norrie Pearce、Michael J. Page、Marcel Kaiser、Brent R. Copp
DOI:10.1021/np200509g
日期:2011.9.23
One tetrahydro-beta-carboline, (-)-7-bromohomotrypargine (1), and three alkylguanidine-substituted beta-carbolines, opacalines A, B, and C (2-4), have been isolated from the New Zealand ascidian Pseudodistoma opacum. The structures of the metabolites were determined by analysis of mass spectrometric and 2D NMR spectroscopic data. Natural products 2 and 3, synthetic debromo analogues 8 and 9, and intermediate 16 exhibited moderate antimalarial activity toward a chloroquine-resistant strain of Plasmodium falciparum, with an IC50 range of 2.5-14 mu M. The biosynthesis of 1-4 is proposed to proceed via a Pictet-Spengler condensation of 6-bromotryptamine and the alpha-keto acid transamination product of either arginine or homoarginine. Cell separation and H-1 NMR analysis of P. opacum identified tetrahydro-beta-carboline 1 to be principally located in the zooids, while fully aromatized analogues 2-4 were localized to the test.