The Traditional Medicine Spilanthes acmella, and the Alkylamides Spilanthol and Undeca‐2E‐ene‐8,10‐diynoic Acid Isobutylamide, Demonstrate In Vitro and In Vivo Antimalarial Activity

Abstract

<jats:p><jats:italic>Spilanthes</jats:italic> spp. are used as traditional herbal medicines in Africa and India to treat malaria. Yet, to date, there are no data on the active constituents or the most effective extraction methods for this indication. The isolated alkylamides, spilanthol and undeca‐2<jats:italic>E</jats:italic>‐ene‐8,10‐diynoic acid isobutylamide, found in <jats:italic>S. acmella</jats:italic> Murr., were shown to have IC<jats:sub>50</jats:sub>s of 16.5 μg/mL and 41.4 μg/mL on <jats:italic>Plasmodium falciparum</jats:italic> strain PFB and IC<jats:sub>50</jats:sub>s of 5.8 μg/mL and 16.3 μg/mL for the chloroquine resistant <jats:italic>P. falciparum</jats:italic> K1 strain, respectively. Further investigations revealed that at relatively low concentrations, spilanthol and the water extract of <jats:italic>S. acmella</jats:italic> reduced the parasitemia 59% and 53% in mice infected with <jats:italic>P. yoelii yoelii</jats:italic> 17XNL at 5 mg/kg and 50 mg/kg, respectively. Unexpectedly, the 95% ethanol extract of <jats:italic>S. acmella</jats:italic> was less effective (36% reduction in parasitemia) at 50 mg/kg. These results provide the first evidence supporting <jats:italic>S. acmella</jats:italic> against malaria and demonstrating active constituents in <jats:italic>S. acmella</jats:italic> against <jats:italic>P. falciparum</jats:italic>. Copyright © 2011 John Wiley &amp; Sons, Ltd.