Referenced in: none

Automatically associated channels: Kir2.3

Title: Epiquinamide: a poison that wasn't from a frog that was.

Authors: Richard W Fitch, Gordon D Sturgeon, Shaun R Patel, Thomas F Spande, H Martin Garraffo, John W Daly, Richard H Blaauw

Journal, date & volume: J. Nat. Prod., 2009 Feb 27 , 72, 243-7

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/19245264

Abstract
In 2003, we reported the isolation, structure elucidation, and pharmacology of epiquinamide (1), a novel alkaloid isolated from an Ecuadoran poison frog, Epipedobates tricolor. Since then, several groups, including ours, have undertaken synthetic efforts to produce this compound, which appeared initially to be a novel, beta2-selective nicotinic acetylcholine receptor agonist. Based on prior chiral GC analysis of synthetic and natural samples, the absolute structure of this alkaloid was established as (1S,9aS)-1-acetamidoquinolizidine. We have synthesized the (1R*,9aS*)-isomer (epi-epiquinamide) using an iminium ion nitroaldol reaction as the key step. We have also synthesized ent-1 semisynthetically from (-)-lupinine. Synthetic epiquinamide is inactive at nicotinic receptors, in accord with recently published reports. We have determined that the activity initially reported is due to cross-contamination from co-occurring epibatidine in the isolated material.