RESUMO
A high performance liquid chromatography (HPLC) method was developed for the simultaneous isolation, on a semi-preparative scale, of chavibetol and methyleugenol from the crude essential oil of P. pseudocaryophyllus leaves. The purity of the isolated compounds and their quantifications were developed using GC/FID. Chavibetol was isolated with high purity (98.7%) and mass recovery (94.6%). The mass recovery (86.4%) and purity (85.3%) of methyleugenol were lower than those of chavibetol. Both compounds were identified on the basis of spectral analysis. The results suggest that the method can provide chavibetol with high purity, mass recovery, and productivity from crude essential, which will be used in bioassays against stored insect pests.
Assuntos
Eugenol/análogos & derivados , Pimenta/química , Cromatografia Líquida de Alta Pressão , Eugenol/isolamento & purificação , Óleos Voláteis/química , Folhas de Planta/química , Óleos de Plantas/químicaRESUMO
Plant-based insecticides can play an important role in integrated insect pest management (IPM), especially in protecting stored grains. The aim of this study was to evaluate the bioactivity of derivatives (powder, ethanolic extract, and essential oil (EO)) from the leaves of Pimenta pseudocaryophyllus (Myrtaceae), a Brazilian native species, against Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), the main insect pest of stored corn. The powder and essential oil prepared from leaves showed a repellent effect. Moreover, the EO exhibited promising insecticidal activity through residual contact (LC50 = 1522 mg kg(-1)) and significantly decreased the F 1 progeny and the percentage of damaged grains. However, the essential oil obtained from P. pseudocaryophyllus leaves did not result in significant mortality of S. zeamais adults after 72 h of exposure by fumigation in concentrations up to 400 µL L(-1) of air. Based on GC-MS analysis, 20 compounds were identified in the essential oil of P. pseudocaryophyllus leaves, being chavibetol (38.14%), methyl eugenol (11.35%), and terpinolene (9.17%) as the major constituents. Essential oil from P. pseudocaryophyllus leaves is an interesting source of compounds with grain-protectant properties and should be analyzed in future studies aiming to develop new bioinsecticides to use in the IPM of stored grains.