Essential Oil Composition and DNA Barcode and Identification of Aniba species (Lauraceae) Growing in the Amazon Region.

Lauraceae species are widely represented in the Amazon, presenting a significant essential oil yield, large chemical variability, various biological applications, and high economic potential. Its taxonomic classification is difficult due to the accentuated morphological uniformity, even among taxa from a different genus. For this reason, the present work aimed to find chemical and molecular markers to discriminate Aniba species collected in the Pará State (Brazil). The chemical composition of the essential oils from Aniba canelilla, A. parviflora, A. rosaeodora, and A. terminalis were grouped by multivariate statistical analysis. The major compounds were rich in benzenoids and terpenoids such as 1-nitro-2-phenylethane (88.34-70.85%), linalool (15.2-75.3%), α-phellandrene (36.0-51.8%), and ß-phellandrene (11.6-25.6%). DNA barcodes were developed using the internal transcribed spacer (ITS) nuclear region, and the matK, psbA-trnH, rbcL, and ycf1 plastid regions. The markers psbA-trnH and ITS showed the best discrimination for the species, and the phylogenic analysis in the three- (rbcL + matK + trnH - psbA and rbcL + matK + ITS) and four-locus (rbcL + matK + trnH - psbA + ITS) combination formed clades with groups strongly supported by the Bayesian inference (BI) (PP:1.00) and maximum likelihood (ML) (BS ≥ 97%). Therefore, based on statistical multivariate and phylogenetic analysis, the results showed a significant correlation between volatile chemical classes and genetic characteristics of Aniba species.

Effects of inoculation by arbuscular mycorrhizal fungi on the composition of the essential oil, plant growth, and lipoxygenase activity of Piper aduncum L.

The aim of this study was to evaluate the changes in the production of secondary metabolites Piper aduncum seedlings were inoculated by spores of the arbuscular mycorrhizal fungi (AMF) Rhizophagus clarus and Claroideoglomus etunicatum. P. aduncum seedlings were inoculated by spores of R. clarus and C. etunicatum and then, development parameters, root colonization, lipoxygenase (LOX) activity, and essential oil (OE) chemical composition were monitored at 30, 60 and 90 days' post-inoculation (dpi). The inoculation had influenced the plant height and root length at 30 and 90 dpi and microscopic analysis of roots showed the presence of hyphae, arbuscules and vesicles in the inoculated plants. Phenylpropanoids and sesquiterpene hydrocarbons were the main compounds in the EO. In the leaves, the concentration of phenylpropanoids showed a decrease, mainly at 60 dpi, with increased sesquiterpene hydrocarbon production. The main compounds were dillapiole, myristicin, and germacrene D; the dillapiole concentration decreased in all treatments. LOX activity had an increase in the leaves and roots at 90 dpi. These results suggest that alterations in the secondary metabolites of P. aduncum can be induced by its mechanisms of resistance during AMF interaction.

Antifungal activity and computational study of constituents from Piper divaricatum essential oil against Fusarium infection in black pepper.

Fusarium disease causes considerable losses in the cultivation of Piper nigrum, the black pepper used in the culinary world. Brazil was the largest producer of black pepper, but in recent years has lost this hegemony, with a significant reduction in its production, due to the ravages produced by the Fusarium solani f. sp. piperis, the fungus which causes this disease. Scientific research seeks new alternatives for the control and the existence of other Piper species in the Brazilian Amazon, resistant to disease, are being considered in this context. The main constituents of the oil of Piper divaricatum are methyleugenol (75.0%) and eugenol (10.0%). The oil and these two main constituents were tested individually at concentrations of 0.25 to 2.5 mg/mL against F. solani f. sp. piperis, exhibiting strong antifungal index, from 18.0% to 100.0%. The 3D structure of the ß-glucosidase from Fusarium solani f. sp. piperis, obtained by homology modeling, was used for molecular docking and molecular electrostatic potential calculations in order to determine the binding energy of the natural substrates glucose, methyleugenol and eugenol. The results showed that ß-glucosidase (Asp45, Arg113, Lys146, Tyr193, Asp225, Trp226 and Leu99) residues play an important role in the interactions that occur between the protein-substrate and the engenol and methyleugenol inhibitors, justifying the antifungal action of these two phenylpropenes against Fusarium solani f. sp. piperis.