Microwave-assisted extraction: an alternative to extract Piper aduncum essential oil / Extração assistida por micro-ondas: uma alternativa para a obtenção do óleo essencial de Piper aduncum

Hydrodistillation and steam distillation have been widely described as methods of obtaining essential oils, however, green technologies with lower levels of energy consumption, time, and solvent have gained increasing prominence. Piper aduncum has confirmed occurrences throughout the Brazilian territory and its essential oil has been described with antifungal, anti-helminthic, antioxidant, and repellent activities. In the present study, we compared the essential oil yield and the dillapiole content from the essential oils obtained using hydrodistillation (Clevenger apparatus) and microwave-assisted extraction (using a prototype extractor). A factorial design was applied to evaluate the influence of the entrance variables fraction diameter (FR) and load of material plant/water volume (LW) on the response variables essential oil yield (Yd) and dillapiole content (DC). Via statistical analysis, a polynomial model was obtained, as well as, the response surface. Hydrodistillation provided higher essential oil yields and the dillapiole content was not statistically influenced by the extraction methods.

Structural analysis of viral infectivity factor of HIV type 1 and its interaction with A3G, EloC and EloB.

The virion infectivity factor (Vif) is an accessory protein, which is essential for HIV replication in host cells. Vif neutralizes the antiviral host protein APOBEC3 through recruitment of the E3 ubiquitin ligase complex.Fifty thousand Vif models were generated using the ab initio relax protocol of the Rosetta algorithm from sets of three- and nine-residue fragments using the fragment Monte Carlo insertion-simulated annealing strategy, which favors protein-like features, followed by an all-atom refinement. In the protocol, a constraints archive was used to define the spatial relationship between the side chains from Cys/His residues and zinc ions that formed the zinc-finger motif that is essential for Vif function. We also performed centroids analysis and structural analysis with respect to the formation of the zinc-finger, and the residue disposal in the protein binding domains. Additionally, molecular docking was used to explore details of Vif-A3G and Vif-EloBC interactions. Furthermore, molecular dynamics simulation was used to evaluate the stability of the complexes Vif-EloBC-A3G and Vif-EloC.The zinc in the HCCH domain significantly alters the folding of Vif and changes the structural dynamics of the HCCH region. Ab initio modeling indicated that the Vif zinc-finger possibly displays tetrahedral geometry as suggested by Mehle et al. (2006). Our model also showed that the residues L146 and L149 of the BC-box motif bind to EloC by hydrophobic interactions, and the residue P162 of the PPLP motif is important to EloB binding.The model presented here is the first complete three-dimensional structure of the Vif. The interaction of Vif with the A3G protein and the EloBC complex is in agreement with empirical data that is currently available in the literature and could therefore provide valuable structural information for advances in rational drug design

Assessment of the PETase conformational changes induced bypoly(ethylene terephthalate) binding

Recently, a bacterium strain of Ideonella sakaiensis was identified with the uncommon ability to degrade the poly(ethylene terephthalate) (PET). The PETase from I. sakaiensis strain 201-F6 (IsPETase) catalyzes the hydrolysis of PET converting it to mono(2-hydroxyethyl) terephthalic acid (MHET), bis(2-hydroxyethyl)-TPA (BHET), and terephthalic acid (TPA). Despite the potential of this enzyme for mitigation or elimination of environmental contaminants, one of the limitations of the use of IsPETase for PET degradation is the fact that it acts only at moderate temperature due to its low thermal stability. Besides, molecular details of the main interactions of PET in the active site of IsPETase remain unclear. Herein, molecular docking and molecular dynamics (MD) simulations were applied to analyze structural changes of IsPETase induced by PET binding. Results from the essential dynamics revealed that the β1-β2 connecting loop is very flexible. This loop is located far from the active site of IsPETase and we suggest that it can be considered for mutagenesis to increase the thermal stability of IsPETase. The free energy landscape (FEL) demonstrates that the main change in the transition between the unbound to the bound state is associated with the β7-α5 connecting loop, where the catalytic residue Asp206 is located. Overall, the present study provides insights into the molecular binding mechanism of PET into the IsPETase structure and a computational strategy for mapping flexible regions of this enzyme, which can be useful for the engineering of more efficient enzymes for recycling plastic polymers using biological systems

Analysis of kojic acid derivatives as competitive inhibitors of tyrosinase: a molecular modeling approach

This research received financial support of CAPES and CNPq.Universidade Federal do Pará. Instituto de Ciências Exatas e Naturais. Laboratório de Modelagem Molecular. Belém, PA, Brasil / Universidade Federal do Pará. Instituto de Ciências Exatas e Naturais. Laboratório de Planejamento e Desenvolvimento de Fármacos. Belém, PA, Brasil.Universidade Federal do Pará. Instituto de Ciências Exatas e Naturais. Laboratório de Sistemas Moleculares Complexos. Belém, PA, Brasil.Universidade Federal do Pará. Instituto de Ciências Exatas e Naturais. Laboratório de Planejamento e Desenvolvimento de Fármacos. Belém, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Universidade Federal do Pará. Instituto de Ciências Exatas e Naturais. Laboratório de Planejamento e Desenvolvimento de Fármacos. Belém, PA, Brasil / Universidade Federal do Oeste do Pará. Instituto de Biodiversidade. Santarém, PA, BrasilUniversidade Federal do Pará. Instituto de Ciências Exatas e Naturais. Laboratório de Modelagem Molecular. Belém, PA, Brasil.Universidade Federal do Pará. Instituto de Ciências Exatas e Naturais. Laboratório de Planejamento e Desenvolvimento de Fármacos. Belém, PA, Brasil.Abstract: Tyrosinases belong to the functional copper-containing proteins family, and their structure contains two copper atoms, in the active site, which are coordinated by three histidine residues. The biosynthesis of melanin in melanocytes has two stages depending on the actions of the natural substrates L-DOPA and L-tyrosine. The dysregulation of tyrosinase is involved in skin cancer initiation. In the present study, using molecular modeling tools, we analyzed the inhibition activity of tyrosinase activity using kojic acid (KA) derivatives designed from aromatic aldehydes and malononitrile. All derivatives showed conformational affinity to the enzyme active site, and a favorable distance to chelate the copper ion, which is essential for enzyme function. Molecular dynamics simulations revealed that the derivatives formed promising complexes, presenting stable conformations with deviations between 0.2 and 0.35 Å. In addition, the investigated KA derivatives showed favorable binding free energies. The most stable KA derivatives showed the following binding free energies: −17.65 kcal mol−1 (D6), −18.07 kcal mol−1 (D2), −18.13 (D5) kcal mol−1, and −10.31 kcal mol−1 (D4). Our results suggest that these derivatives could be potent competitive inhibitors of the natural substrates of L-DOPA (−12.84 kcal mol−1) and L-tyrosine (−9.04 kcal mol−1) in melanogenesi

Analysis of Kojic Acid Derivatives as Competitive Inhibitors of Tyrosinase: A Molecular Modeling Approach

Tyrosinases belong to the functional copper-containing proteins family, and their structure contains two copper atoms, in the active site, which are coordinated by three histidine residues. The biosynthesis of melanin in melanocytes has two stages depending on the actions of the natural substrates L-DOPA and L-tyrosine. The dysregulation of tyrosinase is involved in skin cancer initiation. In the present study, using molecular modeling tools, we analyzed the inhibition activity of tyrosinase activity using kojic acid (KA) derivatives designed from aromatic aldehydes and malononitrile. All derivatives showed conformational affinity to the enzyme active site, and a favorable distance to chelate the copper ion, which is essential for enzyme function. Molecular dynamics simulations revealed that the derivatives formed promising complexes, presenting stable conformations with deviations between 0.2 and 0.35 Å. In addition, the investigated KA derivatives showed favorable binding free energies. The most stable KA derivatives showed the following binding free energies: −17.65 kcal mol−1 (D6), −18.07 kcal mol−1 (D2), −18.13 (D5) kcal mol−1, and −10.31 kcal mol−1 (D4). Our results suggest that these derivatives could be potent competitive inhibitors of the natural substrates of L-DOPA (−12.84 kcal mol−1) and L-tyrosine (−9.04 kcal mol−1) in melanogenesis

Determination of macro and trace element levels in honey from the lower amazonian region, Brazil

Project 88881.159143/2017-01 funded by CAPES (Coordination of Improvement of Higher Education Personnel) and FAPESPA (Amazonia Foundation for Studies and Research in Pará)Universidade Federal do Oeste do Pará. Instituto de Biodiversidade e Florestas. Santarém, PA, Brazil.Universidade Federal do Oeste do Pará. Instituto de Biodiversidade e Florestas. Santarém, PA, Brazil.Universidade Federal do Oeste do Pará. Instituto de Biodiversidade e Florestas. Santarém, PA, Brazil.Universidade Federal do Oeste do Pará. Instituto de Biodiversidade e Florestas. Santarém, PA, Brazil.Universidade Federal do Oeste do Pará. Instituto de Biodiversidade e Florestas. Santarém, PA, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Universidade Federal do Oeste do Pará. Instituto de Biodiversidade e Florestas. Santarém, PA, Brazil.The aim of this study was to quantify the macro and trace element concentrations in Apis mellifera and Melipona interrupta honey samples from the Lower Amazonian region in order to evaluate if the samples of different geographical origin and/or species could be distinguished by their mineral content. In addition, it was evaluated the presence of potentially toxic metals in honey samples. The metal contents were determined by inductively coupled plasma optical emission spectrometry (ICP OES) and the most abundant metals found in the samples were K, Ca, Mg, and Na. The total metal (K, Ca, Mg, Na, Cd, Co, Ni, Fe, Mn, Cr, Al and Ba) concentration ranged from 127.7 ± 1.4 to 1844.4 ± 45.2 µg g-1 and from 102.7 ± 2.0 to 639.0 ± 15.3 µg g-1 in Apis mellifera and Melipona interrupta honey, respectively. All mineral content levels found in the honey samples were lower than the maximum established by Brazilian and international law (Cd and Cr 0.1 μg g-1, Pb 0.30 μg g-1, Ni 5 μg g-1, Cu 10 μg g-1, Zn 50 μg g-1). Furthermore, Cu, Pb, and Zn were not detected in any of the samples. However, potentially toxic elements, such as Cd, Co, and Ni, were detected in most of the commercial samples and in Apis mellifera honey from beehives that were close to livestock fields and/or soybean areas. Hierarchical cluster analysis (HCA) was used to study the mineral contents and it was possible to distinguish eight different groups of honey. However, the Melipona interrupta honey could not be separated into different groups

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

Vif theoretical structure showing the binding sites to the proteins of E3 ubiquitin ligase complex and to the A3G and A3F.

<p>The PPLP motif is located away from the hydrophobic region of HCCH domain and the BC-box exhibit the SLQ(Y/F)LA motif.</p

The average atomic B-factor per residue is plotted as function of the residue number and was obtained after 10ns of molecular dynamics simulation.

<p>These figure information have been adapted from Wissing et al., <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089116#pone.0089116-Wissing1" target="_blank">[87]</a> to the Vif sequence modeled.</p

Assembled complex of Vif-EloBC-A3G N-CDA. Panels show interactions of Vif with A3G, EloC, EloB and (in the clockwise direction).

<p>In the first panel, the residues L146 and L149 from Vif BC-box are involved in EloC interaction (Vif is in cyan and EloC in orange). The second panel shows that in the N-terminal region, Vif interact via hydrogen bonding with A3G (Vif is in cyan and A3G in red). Last panel shows residues L161 and P162 from Vif Cullin-box interacting by hydrophobic interaction with the residue E97 and P96 from the C-terminal end of EloB (Vif is in cyan and EloB in green).</p