Calcium oxalate crystals and methyl salicylate as toxic principles of the fresh leaves from Palicourea longiflora, an endemic species in the Amazonas state.

The species of the genus Palicourea (Rubiaceae family) is well-known for its toxicity towards animals, particularly livestock. This work reports the occurrence of skin irritation during the manipulation of Palicourea longiflora, considering the prevalence of the monofluoracetic acid (MFAA) and another toxic compound: methyl salicylate. The MFAA was identified by 19F-NMR and methyl salicylate by gas chromatography linked to mass spectrometry (GC/MS) analysis. Additionally, an anatomical study of leaves had been used to explain the mechanism of penetration of the toxic principles.