N-methyl-5-carboxamide-2-pyridone from Mallotus barbatus: AÂ chemosystematic marker of the Euphorbiaceae genus Mallotus

► N1-methyl-2-pyridone-5-carboxamide was isolated from Mallotus barbatus. ► This compound has previously only been identified twice: in Trewia and Mallotus. ► These two Euphorbiaceae genera are placed in the same subtribe Rottlerinae. ► According to a recent molecular phylogenetic study, Trewia was merged with Mallotus. ► This derivative of nicotinamide could be a chemotaxonomical marker of Mallotus.