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Antimalarial β-carbolines from the New Zealand ascidian Pseudodistoma opacum.

Journal of natural products (2011-08-19)
Susanna T S Chan, A Norrie Pearce, Michael J Page, Marcel Kaiser, Brent R Copp
ABSTRACT

One tetrahydro-β-carboline, (-)-7-bromohomotrypargine (1), and three alkylguanidine-substituted β-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 μM. The biosynthesis of 1-4 is proposed to proceed via a Pictet-Spengler condensation of 6-bromotryptamine and the α-keto acid transamination product of either arginine or homoarginine. Cell separation and 1H NMR analysis of P. opacum identified tetrahydro-β-carboline 1 to be principally located in the zooids, while fully aromatized analogues 2-4 were localized to the test.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Podophyllotoxin
Sigma-Aldrich
Miltefosine, ≥98% (perchloric acid titration)