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The essential oils (EOs) of Guatteria schomburgkiana (Gsch) and Xylopia frutescens (Xfru) (Annonaceae) were obtained by hydrodistillation, and their chemical composition was evaluated by gas chromatography-mass spectrometry (GC/MS). Herbicide activity was measured by analyzing the seed germination percentage and root and hypocotyl elongation of two invasive species: Mimosa pudica and Senna obtusifolia. The highest yield was obtained for the EO of Xfru (1.06%). The chemical composition of Gsch was characterized by the presence of the oxygenated sesquiterpenes spathulenol (22.40%) and caryophyllene oxide (14.70%). Regarding the EO of Xfru, the hydrocarbon monoterpenes α-pinene (35.73%) and β-pinene (18.90%) were the components identified with the highest concentrations. The germination of seeds of S. obtusifolia (13.33 ± 5.77%) showed higher resistance than that of seeds of M. pudica (86.67 ± 5.77%). S. obtusifolia was also more sensitive to the EO of Xfru in terms of radicle (55.22 ± 2.72%) and hypocotyl (71.12 ± 3.80%) elongation, while M. pudica showed greater sensitivity to the EO of Gsch. To screen the herbicidal activity, the molecular docking study of the major and potent compounds was performed against 4-hydroxyphenylpyruvate dioxygenase (HPPD) protein. Results showed good binding affinities and attributed the strongest inhibitory activity to δ-cadinene for the target protein. This work contributes to the study of the herbicidal properties of the EOs of species of Annonaceae from the Amazon region.

The essential oils (EOs) of Duguetia echinophora, D. riparia, Xylopia emarginata and X. frutescens (Annonaceae) were obtained by hydrodistillation and the chemical composition was analyzed by GC-MS. An antioxidant assay using the ABTS and DPPH radicals scavenging method and cytotoxic assays against Artemia salina were also performed. We evaluated the interaction of the major compounds of the most toxic EO (X. emarginata) with the binding pocket of the enzyme Acetylcholinesterase, a molecular target related to toxicity in models of Artemia salina. The chemical composition of the EO of D. echinophora was characterized by β-phellandrene (39.12%), sabinene (17.08%) and terpinolene (11.17%). Spathulenol (22.22%), caryophyllene oxide (12.21%), humulene epoxide II (11.86%) and allo-aromadendrene epoxide (10.20%) were the major constituents of the EO from D. riparia. Spathulenol (5.65%) and caryophyllene oxide (5.63%) were the major compounds of the EO from X. emarginata. The EO of X. frutescens was characterized by α-pinene (20.84%) and byciclogermacrene (7.85%). The results of the radical scavenger DPPH assays ranged from 15.87 to 69.38% and the highest percentage of inhibition was observed for the EO of X. emarginata, while for ABTS radical scavenging, the antioxidant capacity of EOs varied from 14.61 to 63.67%, and the highest percentage of inhibition was observed for the EO of X. frutescens. The EOs obtained from D. echinophora, X. emarginata and X. frutescens showed high toxicity, while the EO of D. riparia was non-toxic. Because the EO of X. emarginata is the most toxic, we evaluated how its major constituents were able to interact with the Acetylcholinesterase enzyme. The docking results show that the compounds are able to bind to the binding pocket through non-covalent interactions with the residues of the binding pocket. The species X. emarginata and X. frutescens are the most promising sources of antioxidant compounds; in addition, the results obtained for preliminary cytotoxicity of the EOs of these species may also indicate a potential biological activity.

Essential oils are biosynthesized in the secondary metabolism of plants, and in their chemical composition, they can be identified different classes of compounds with potential antioxidant and biological applications. Over the years in the Amazon, several species of aromatic plants were discovered and used in traditional medicine. The literature has shown that essential oils extracted from amazon species have several biological activities, such as antioxidant, antibacterial, antifungal, cytotoxic, and antiprotozoal activities. These activities are related to the diversified chemical composition found in essential oils that, by synergism, favors its pharmacological action. In light of this vital importance, this study aimed at performing a review of the literature with particular emphasis on the chemical composition and biological activities in studies conducted with species collected in the Amazon, taking into consideration in particular the last 10 years of collection and research.