<jats:title>Abstract</jats:title><jats:p>Two new alkaloids, dehydronitraramine (<jats:bold>1</jats:bold>) and <jats:italic>N</jats:italic>‐formylmyrionine (<jats:bold>2</jats:bold>) were isolated from the leaves of <jats:italic>Myrioneuron nutans</jats:italic>, and their structures were determined from spectroscopic analysis, including mass spectrometry and 2D‐NMR spectroscopy. The absolute configuration 8<jats:italic>S</jats:italic>, 9<jats:italic>R</jats:italic>, 10<jats:italic>S</jats:italic> of <jats:italic>N</jats:italic>‐formylmyrionine (<jats:bold>2</jats:bold>) was established by <jats:italic>N</jats:italic>‐formylation of the known (8<jats:italic>S</jats:italic>,9<jats:italic>R</jats:italic>,10<jats:italic>S</jats:italic>)‐myrionine and then comparison of the optical rotation of the natural <jats:italic>N</jats:italic>‐formylmyrionine (<jats:bold>2</jats:bold>) with that of the semi‐synthetic (8<jats:italic>S</jats:italic>,9<jats:italic>R</jats:italic>,10<jats:italic>S</jats:italic>)‐<jats:italic>N</jats:italic>‐formylmyrionine. Dehydronitraramine (<jats:bold>1</jats:bold>) displayed a moderate antiplasmodial activity against <jats:italic>Plasmodium</jats:italic> <jats:italic>falciparum</jats:italic> with an IC<jats:sub>50</jats:sub> value of 16 μ<jats:sc>M</jats:sc>, whereas both <jats:bold>1</jats:bold> and <jats:bold>2</jats:bold> showed a weak cytotoxicity against KB cells.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)