Due to the potential of phytochemicals as therapeutic agents, there is increased interest in plant compounds with this biological activity, such as the essential oils of medicinal and aromatic plants. This study assessed the antioxidant activity of essential oils from the species Croton grewioides and its major compounds (CGR106 and CGR126 – 29.51% and 42.68% of eugenol; CGR126 and CGR112 – 45.97% and 85.58% of methyl eugenol; CGR106 – 59.85% of methyl chavicol). Antioxidant activities were evaluated by the systems 2,2-diphenyl-1-picryl-hydrazyl (DPPH), 2,2ʹ-azinobis (3-ethylbenzoathazoline-6-sulfonic acid) (ABTS), Ferric Reducing Ability (FRAP) and co-oxidation of β-carotene/linoleic acid. The best results were found in the essential oils CGR106 and CGR126, from C. grewioides. Samples with eugenol in their composition showed greater free-radical stabilization capacity. Essential oils of both accessions presented antioxidant capacity in the methods tested.

The aim of this work was to evaluate the antifungal activity of essential oils (EOs) of Lippia gracilis and Lippia sidoides accessions, their major compounds and nanoemulsions. Nanoemulsions with 18% of EO or major compound were produced by spontaneous emulsification method. The EO of two L. gracilis accessions (LGRA-106 and LGRA-109) and two L. sidoides accessions (LSID-102 and LSID-104) were extracted by hydrodistillation and the major compounds thymol and carvacrol were purchased commercially. Antifungal activity was tested against Lasiodiplodia theobromae by calculating the percentage of inhibition of mycelial growth caused by different concentrations (0.1, 0.5, 1.0, 5.0, and 10.0 mL.L-1), in relation to the control. The EOs and their respective nanoemulsions presented as major compounds thymol (LGRA-106: 61.84% and Nano-106: 63.43%; LSID-102: 64.07% and Nano-102: 83.03%) or carvacrol (LGRA-109: 54.56% and Nano-109: 45.63%; LSID-104: 69.06% and Nano-104: 38.66%). Nano-104 presented 35.91% of an unidentified compound. The fungicidal activity of the EOs was similar to that of the major compounds, with a minimum fungicidal concentration of 1.0 mL.L-1 for LGRA-106, LSID-102 as well as for thymol, and 0.5 mL.L-1 for LGRA-109, LSID-104 as well as for carvacrol. The nanoemulsions were only able to reduce the mycelial growth of the fungus except for Nano-104 that exhibited fungicidal activity at the concentration of 10 ml.L-1. It was possible to observe that the EOs exhibited greater toxicity against L. theobromae than the nanoemulsions. These results can help in the development of products for the control of this important phytopathogen.

This study aimed to evaluate the antimicrobial activity of essential oils extracted from two genotypes of Croton tetradenius Baill. individually and in combination with antibiotics against Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae. Camphor (13.95 %) was found to be the most dominant compound in essential oil obtained from C. tetradenius CTE101 followed by p-cymene (13.37 %) and trans-ascaridole (8.07 %), while the C. tetradenius CTE407 essential oil presented p-cymene (17.55 %), trans-ascaridole (14.0 %) and 1,8-cineole (12.12 %) as main compounds. High concentrations of essential oils were necessary to inhibit the bacterial strains evaluated, with MIC values ranging from 2.8 to 5.6 mg/mL. CTE407 showed lower values compared to CTE101. The checkerboard dilution method demonstrated that combinations of essential oils with antibiotics (ciprofloxacin and meropenem) resulted in a synergistic effect, with the exception of the combination of CTE101 with ciprofloxacin against E. coli. These results indicate that the essential oils tested have the potential to be used in combination with traditional antibiotics. When used in combination with essential oils, a lower concentration of antibiotics was required to inhibit the growth of microorganisms tested.

The aim of this work was to analyse the chemical diversity of Lantana camara L. essential oils of native populations from Northeast Brazil. A total of 105 plants were collected in twenty-one municipalities from the state of Sergipe. The essential oil content ranged from 0.1% to 0.5%. Twenty-nine compounds and seven chemical clusters were identified and characterised by different numbers of plants and major compounds. E-caryophyllene (4.1–53.4%), germacrene D (2.8–48.3%), bicyclogermacrene (0.0–18.9%), α-humulene (0.7–39.0%) and α-curcumene (24.9–34.3%) were found in higher amounts and formed the chemical clusters. Results revealed chemical variability among L. camara native populations from Northeast Brazil. This knowledge was fundamental for the implantation of a collection of L. camara in the Active Germplasm Bank of Medicinal and Aromatic Plants of the Federal University of Sergipe and will allow studies on the potential biological activities of the essential oil from conserved plants.

Zephyranthes irwiniana (Ravenna) Nic. García is an endemic, red list threatened species from the Brazilian savanna (Cerrado) with pharmacological potential to treat the symptoms of Alzheimer’s Disease (AD). This work analyzed the vegetative growth and phytochemistry of its potential compounds, in response to variations in sucrose concentration and activated carbon (AC). Seeds were germinated in vitro and in the greenhouse. The in vitro bulbs were separated in six treatments with different sucrose concentrations (30, 45 and 60 gL⁻¹) and/or AC (1 gL⁻¹). Biomass increases in individuals grown in the greenhouse were higher than those cultivated in vitro. Sucrose concentration significantly increased biomass and root number. AC had a positive influence on leaf and root size, and a negative influence on root number. GC–MS analyses indicated great variation in the abundance of α-terpenyl-acetate, ethyl linoleate, clionasterol and lycorine between treatments, with maximum concentrations of 53.06%, 38.68, 14.34% and 2.57%, respectively. Histolocalization tests indicated the presence of alkaloids in the leaf chlorenchyma and bulb cataphylls. Finally, the present study provided new evidence that the constitution of the culture medium directly influences the vegetative growth and phytochemistry of this species, providing a good medium condition for propagating the species under threat.