Morphoanatomical, Histochemical, and Essential Oil Composition of the Plectranthus ornatus Codd. (Lamiaceae).

Plectranthus ornatus is a medicinal and aromatic plant used in traditional and alternative medicine. In this study, leaves of P. ornatus were collected in two cities of the state of Pará, "Quatipuru" and "Barcarena", and were used with the objective of analyzing, through morphoanatomical data and histochemical and phytochemical studies of essential oil, the samples present structural differences and differences in their chemical composition. Anatomical and histochemical analyses were performed by transverse, using longitudinal sections of 8 µm to 10 µm to perform epidermal dissociation, diaphonization, and tests to identify classes of secondary metabolites. The essential oils were isolated by hydrodistillation, and the identification of the chemical composition was performed by gas chromatography coupled with mass spectrometry. The anatomical study shows that there is no difference between specimens collected in different locations, and stellate trichomes were identified. The histochemical study detected total lipids and acids, terpenes, polysaccharides, phenolic compounds, tannins, alkaloids, and calcium oxalate. The low essential oil yield may be related to the low density of secretory cells (glandular trichomes), the unidentified compounds in the highest concentration in the essential oil were in relation to the chemical composition of the essential oils, and the major compounds were α-pinene, sabinene, (E)-caryophyllene, caryophyllene oxide, and oct-1-en-3-ol. The results provide new information about the anatomy and histochemistry of P. ornatus.

In Silico Evaluation of the Antimicrobial Activity of Thymol-Major Compounds in the Essential Oil of Lippia thymoides Mart. & Schauer (Verbenaceae).

In this paper, we evaluated the drug-receptor interactions responsible for the antimicrobial activity of thymol, the major compound present in the essential oil (EO) of Lippia thymoides (L. thymoides) Mart. & Schauer (Verbenaceae). It was previously reported that this EO exhibits antimicrobial activity against Candida albicans (C. albicans), Staphylococcus aureus (S. aureus), and Escherichia coli (E. coli). Therefore, we used molecular docking, molecular dynamics simulations, and free energy calculations to investigate the interaction of thymol with pharmacological receptors of interest to combat these pathogens. We found that thymol interacted favorably with the active sites of the microorganisms' molecular targets. MolDock Score results for systems formed with CYP51 (C. albicans), Dihydrofolate reductase (S. aureus), and Dihydropteroate synthase (E. coli) were -77.85, -67.53, and -60.88, respectively. Throughout the duration of the MD simulations, thymol continued interacting with the binding pocket of the molecular target of each microorganism. The van der Waals (ΔEvdW = -24.88, -26.44, -21.71 kcal/mol, respectively) and electrostatic interaction energies (ΔEele = -3.94, -11.07, -12.43 kcal/mol, respectively) and the nonpolar solvation energies (ΔGNP = -3.37, -3.25, -2.93 kcal/mol, respectively) were mainly responsible for the formation of complexes with CYP51 (C. albicans), Dihydrofolate reductase (S. aureus), and Dihydropteroate synthase (E. coli).

First report on the Annona exsucca DC. Essential oil and in silico identification of potential biological targets of its major compounds.

In the present study, the essential oil (EO) of Annona exsucca DC. or Rollinia exsucca was extracted by hydrodistillation, and the identification and quantification of volatile compounds were performed by GC-MS and GC-FID. A. exsucca leaves were collected from the Magalhães Barata, northeast of the State of Pará (Brazil) in March and September of 2019. Moreover, we used computational approaches to evaluate possible biological targets for the major compounds of the EO. In the sample obtained in March, 50 compounds were identified, with hydrocarbon sesquiterpenes being the predominant ones with the content of 80.52%. In the sample collected in September, 58 compounds were identified, and the chemical class of hydrocarbon monoterpenes and sesquiterpenes were the dominant ones with contents of 43.36 and 31.29%, respectively. Computational methods demonstrated that some major compounds have potential biological activity against some strains of pathogenic bacteria, as well as against molecular targets involved in cancer development.

Chemical Composition and Antioxidant Activity of Essential Oils from Leaves of Two Specimens of Eugenia florida DC.

Eugenia florida DC. belongs to the Myrtaceae family, which is present in almost all of Brazil. This species is popularly known as pitanga-preta or guamirim and is used in folk medicine to treat gastrointestinal problems. In this study, two specimens of Eugenia florida (Efl) were collected in different areas of the same region. Specimen A (EflA) was collected in an area of secondary forest (capoeira), while specimen B (EflB) was collected in a floodplain area. The essential oils (EOs) were extracted from both specimens of Eugenia florida by means of hydrodistillation. Gas chromatography coupled to mass spectrometry (GC/MS) was used to identify the volatile compounds present, and the antioxidant capacity of the EOs was determined by antioxidant capacity (AC-DPPH) and the Trolox equivalent antioxidant (TEAC) assay. For E. florida, limonene (11.98%), spathulenol (10.94%) and α-pinene (5.21%) were identified as the main compounds of the EO extracted from sample A, while sample B comprised selina-3,11-dien-6α-ol (12.03%), eremoligenol (11.0%) and γ-elemene (10.70%). This difference in chemical composition impacted the antioxidant activity of the EOs between the studied samples, especially in sample B of E. florida. This study is the first to report on the antioxidant activity of Eugenia florida DC. essential oils.

Drying Effects on Chemical Composition and Antioxidant Activity of Lippia thymoides Essential Oil, a Natural Source of Thymol.

Leaves of Lippia thymoides (Verbenaceae) were dried in an oven at 40, 50 and 60 °C and the kinetic of drying and the influence of the drying process on the chemical composition, yield, and DPPH radical scavenging activity of the obtained essential oils were evaluated. The composition of the essential oils was determined with gas chromatography-mass spectrometry and gas chromatography-flame ionization detection analyses. The influence of drying on the chemical composition of the essential oils of L. thymoides was evaluated by multivariate analysis, and their antioxidant activity was investigated via the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The Midilli model was the most appropriate to describe the behavior of drying kinetic data of L. thymoides leaves. Thymol was the major compound for all analyzed conditions; the maximum content was obtained from fresh leaves (62.78 ± 0.63%). The essential oils showed DPPH radical scavenging activity with an average of 73.10 ± 12.08%, and the fresh leaves showed higher inhibition (89.97 ± 0.31%). This is the first study to evaluate the influence of drying on the chemical composition and antioxidant activity of L. thymoides essential oils rich in thymol.

Physiological performance and chemical compositions of the Eryngium foetidum L. (Apiaceae) essential oil cultivated with different fertilizer sources.

The present work proposed an evaluation of the physiological performance, yield and chemical profile of the essential oil obtained from leaves and roots of Eryngium foetidum L. (Apiaceae) cultivated using different fertilizer sources. The other gas exchange and chlorophyll a fluorescence parameter was not different, suggested that the photosystem II was not affected by the different fertilizer sources. Highest essential oil yield was obtained in leaf samples cultivated with the mineral fertilizer (0.18%) and control conditions (0.22%), while it was obtained by mineral fertilization in the case of root samples (0.22%). The principal component analysis - PCA and hierarchical cluster analysis - HCA showed two groups: the first was formed by roots (OrgR, MinR and ConR), characterized by the constituents 2,3,4-Trimethylbenzaldehyde, Muurola-4,10(14)-dien-1ß-ol, Isoshyobunone, para-Mint-1,5-dien-8-ol, 6-Canphenone, (E)-γ-Atlantone and (E)-ß-Farnesene; and the second group formed by leaves (OrgF, MinF, ConF), related to (2E)-2-Dodecenal, t-2-Tetradecenal, 1-Dodecanal, 1-Decanal, Tetradecanal, γ-Terpinene, Mesitylene and ρ-Cymene.

Chemical Composition, Antimicrobial Properties of Siparuna guianensis Essential Oil and a Molecular Docking and Dynamics Molecular Study of its Major Chemical Constituent.

The essential oil of Siparuna guianensis was obtained by hydrodistillation. The identification of the chemical compounds was performed by gas chromatography coupled with mass spectrometry (GC/MS). Antimicrobial activity was investigated for four microorganisms: Streptococcus mutans (ATCC 3440), Enterococcus faecalis (ATCC 4083), Escherichia coli (ATCC 25922), and Candida albicans (ATCC-10231). The studies of doping and molecular dynamics were performed with the molecule that presented the highest concentration of drug-target proteins, 1IYL (C. albicans), 1C14 (E. coli), 2WE5 (E. faecalis), and 4TQX (S. mutans). The main compounds identified were: Curzerene (7.1%), γ-Elemene (7.04%), Germacrene D (7.61%), trans-ß-Elemenone (11.78%), and Atractylone (18.65%). Gram positive bacteria and fungi were the most susceptible to the effects of the essential oil. The results obtained in the simulation showed that the major compound atractylone interacts with the catalytic sites of the target proteins, forming energetically favourable systems and remaining stable during the period of molecular dynamics.

First Report on Yield and Chemical Composition of Essential Oil Extracted from Myrcia eximia DC (Myrtaceae) from the Brazilian Amazon.

The essential oil (EO) of plants of the Myrtaceae family has diverse chemical composition and several applications. However, data on the oil yield, its composition, and its complete chemistry are still unavailable for some species belonging to this family, such as Myrcia eximia DC. In this study, the chemical compositions of the EOs of Myrcia eximia were evaluated by using gas chromatography (GC) alone and gas chromatography coupled with mass spectrometry (GC-MS). Samples for both evaluations were collected from the city of Magalhães Barata, State of Pará, Brazil, in 2017 and 2018. For the plant material collected in 2017, EO was obtained by hydrodistillation (HD) only, while, for the material collected in 2018, EO was obtained by hydrodistillation and steam distillation (SD), in order to evaluate the differences in chemical composition and mass yield of the EO. The yields of (E)-caryophyllene were 15.71% and 20.0% for the samples collected by HD in 2017 and 2018, respectively, while the yield was 15.0% for the sample collected by SD in 2018. Hexanal was found to be the major constituent in the EO obtained by HD, with yield of up to 26.09%. The oil yields reached 0.08% by using SD, and 0.01% and 0.36% for the samples collected in 2017 and 2018, respectively, using HD. The results of this study provide new information about the mass yield and chemical composition of Myrcia eximia DC, and they can add value and income to traditional populations, as well as facilitate the preservation of this species.

Chemical profile of Lippia thymoides, evaluation of the acetylcholinesterase inhibitory activity of its essential oil, and molecular docking and molecular dynamics simulations.

The essential oils of the fresh and dry flowers, leaves, branches, and roots of Lippia thymoides were obtained by hydrodistillation and analyzed using gas chromatography (GC) and GC-mass spectrometry (MS). The acetylcholinesterase inhibitory activity of the essential oil of fresh leaves was investigated on silica gel plates. The interactions of the key compounds with acetylcholinesterase were simulated by molecular docking and molecular dynamics studies. In total, 75 compounds were identified, and oxygenated monoterpenes were the dominant components of all the plant parts, ranging from 19.48% to 84.99%. In the roots, the main compounds were saturated and unsaturated fatty acids, having contents varying from 39.5% to 32.17%, respectively. In the evaluation of the anticholinesterase activity, the essential oils (detection limit (DL) = 0.1 ng/spot) were found to be about ten times less active than that of physostigmine (DL = 0.01ng/spot), whereas thymol and thymol acetate presented DL values each of 0.01 ng/spot, equivalent to that of the positive control. Based on the docking and molecular dynamics studies, thymol and thymol acetate interact with the catalytic residues Ser203 and His447 of the active site of acetylcholinesterase. The binding free energies (ΔGbind) for these ligands were -18.49 and -26.88 kcal/mol, demonstrating that the ligands are able to interact with the protein and inhibit their catalytic activity.