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Spearmint (Mentha spicata L.) has been widely studied for its diversity of compounds for product generation. However, studies describing the chemical and biological characteristics of commercial spearmint materials from different origins are scarce. For this reason, this research aimed to bioprospecting spearmint from three origins: Colombia (Col), Mexico (Mex), and Egypt (Eg). We performed a biological activity analysis, such as FRAP, DPPH, and ABTS, inhibition potential of S. pyogenes, K. pneumoniae, E. coli, P. aeuroginosa, S. aureus, S aureus Methicillin-Resistant, and E. faecalis. Furthermore, we performed chemical assays, such as total polyphenol and rosmarinic acid, and untargeted metabolomics via HPLC-MS/MS. Finally, we developed a causality analysis to integrate biological activities with chemical analyses. We found significant differences between the samples for the total polyphenol and rosmarinic acid contents, FRAP, and inhibition analyses for Methicillin-Resistant S. aureus and E. faecalis. Also, clear metabolic differentiation was observed among the three commercial materials evaluated. These results allow us to propose data-driven uses for the three spearmint materials available in current markets. [ABSTRACT FROM AUTHOR]

Steel fibers increase the strain capacity of normal and high-strength concrete columns. Availability of normal or high-strength concrete and conventional reinforcement is limited for low-rise concrete houses in rural areas. It is in the interest of society, of the thousands of people that live in those houses, that house performance be evaluated. This paper assesses the behavior of 18 short, square-section columns made of low-strength concrete reinforced with hybrid steel bars and micro-fibers under axial compressive loads. The investigated variables were the steel ratio (2.8% and 5.6%) and layout of transverse reinforcement and the fiber dosage (10 kg/m3 and 20 kg/m3). Response of the specimens was assessed in terms of crack patterns and failure modes, compressive stress–strain curves and the contribution of concrete, conventional steel reinforcement and steel fibers to the performance of the columns. Experimental stress–strain curves of the columns were compared with those computed using existing analytical models. The comparison of the measured and calculated stress–strain curves showed that it is required to calibrate a model for the columns with the key characteristics included in the experimental campaign. The study developed a behavioral model that is consistent with the trends of the results measured. The effectiveness of the proposed model was evaluated through statistical analysis. [ABSTRACT FROM AUTHOR]

Cyclin-dependent kinase 2 (CDK2) is an important member of the CDK family exerting its most important function in the regulation of the cell cycle. It catalyzes the transfer of the gamma phosphate group from an ATP (adenosine triphosphate) molecule to a Serine/Threonine residue of a peptide substrate. Due to the importance of this enzyme, and protein kinases in general, a detailed understanding of the reaction mechanism is desired. Thus, in this work the phosphoryl transfer reaction catalyzed by CDK2 was revisited and studied by means of hybrid quantum mechanics/molecular mechanics (QM/MM) calculations. Our results suggest that the base-assisted mechanism is preferred over the substrate-assisted pathway when one Mg2+ is present in the active site, in agreement with a previous theoretical study. The base-assisted mechanism resulted to be dissociative, with a potential energy barrier of 14.3 kcal/mol, very close to the experimental derived value. An interesting feature of the mechanism is the proton transfer from Lys129 to the phosphoryl group at the second transition state, event that could be helping in neutralizing the charge on the phosphoryl group upon the absence of a second Mg2+ ion. Furthermore, important insights into the mechanisms in terms of bond order and charge analysis were provided. These descriptors helped to characterize the synchronicity of bond forming and breaking events, and to characterize charge transfer effects. Local interactions at the active site are key to modulate the charge distribution on the phosphoryl group and therefore alter its reactivity. [ABSTRACT FROM AUTHOR]

Objective: cognitive reserve (CR) is defined as the brain's ability to tolerate and support neuropathologies before reaching the threshold that gives rise to clinical manifestations. Due to the increase in life expectancy, this concept arises with the purpose of identifying factors that maintain the functionality and independence of the elderly, thus favoring the quality of life in this population group. The objective of this study was to analyze the relationship between the time of exposure to directed musical practice and the cognitive performance of healthy older adults. Methodology: Observational, descriptive study including 11 healthy, older adults with a history of guided musical practice. The Cognitive Reserve questionnaire was applied and neurocognitive performance was evaluated using the K-BIT intellectual capacity test and the NEURONORMA COLOMBIA battery. Results: in people with musical training, cognitive reserve was associated to better performance in tasks of denomination, visuospatial and verbal working memory, focused and alternating attention, phonological verbal fluency and semantic performance. On the other hand, the time of exposure to directed musical practice was associated to better performance in semantic language and favored working memory and in the long term. Conclusions: time of exposure to directed musical practice, age, and educational level favor cognitive reserve in the linguistic and mnemonic domains. [ABSTRACT FROM AUTHOR]

The Amaryllidaceae family has proven to be a rich source of active compounds, which are characterized by unique skeleton arrangements and a broad spectrum of biological activities. The aim of this work was to perform the first detailed study of the alkaloid constituents of Hippeastrum reticulatum (Amaryllidaceae) and to determine the anti-parasitological and cholinesterase (AChE and BuChE) inhibitory activities of the epimers (6α-hydroxymaritidine and 6β-hydroxymaritidine). Twelve alkaloids were identified in H. reticulatum: eight known alkaloids by GC-MS and four unknown (6α-hydroxymaritidine, 6β-hydroxymaritidine, reticulinine and isoreticulinine) by NMR. The epimer mixture (6α-hydroxymaritidine and 6β-hydroxymaritidine) showed low activity against all protozoan parasites tested and weak AChE-inhibitory activity. Finally, a molecular docking analysis of AChE and BuChE proteins showed that isoreticulinine may be classified as a potential inhibitory molecule since it can be stabilized in the active site through hydrogen bonds, π-π stacking and hydrophobic interactions. [ABSTRACT FROM AUTHOR]

Under general seismic loading, reinforced concrete columns may be subjected to lateral loads in more than one direction. Available experimental data on columns subjected to bidirectional forces indicate that higher levels of damage and a higher loss of ductility and strength have been observed compared to similar tests under unidirectional shear forces. In this study, an experimental program was conducted in which six lightly reinforced concrete columns were subjected to unidirectional and bidirectional cyclic shear forces. This observation was used to identify the mechanisms and parameters governing the behavior of columns subjected to cyclic bidirectional lateral loads. Hence, a new conceptual model was developed to obtain the capacity of member. The shear forces were analyzed and an analytical formulation was derived to account for the effects in the concrete stress-strain relationship, the moment-curvature diagram and the plastic hinge length. These equations were used along with a structural model with concentrated plastic hinges to obtain the capacity curve of the column. The results of the formulations developed were verified using the results of the experiments performed on columns subjected to unidirectional and bidirectional cyclic lateral forces. [ABSTRACT FROM AUTHOR]

The most stable form of a B36 cluster has a central hexagonal hole. Such an interesting finding has led to the possible synthesis of a 2D boron sheet by employing the B36 cluster as the building unit. Herein, a DFT study to investigate the reason for the central location of the hexagonal hole in the B36 cluster is presented. The results show that the B36 cluster with a central hexagonal hole is highly thermodynamically and kinetically stable. More importantly, such high stability is further understood through chemical bonding analysis. [ABSTRACT FROM AUTHOR]

Density functional theory computations at the BP86-D3/def2-TZVP level are reported for the CpE–Cr(CO)5 complexes (E = Group 13 element). In principle, we have answered two important facts: first the nature and trend of the E–Cr bonding along B to Tl complexes; second, the deviation of Cp (centroid)-E–Cr angle in In and Tl from linearity. The bonding situation in the complexes is examined via the natural bond orbital, adaptive natural density partitioning, and energy decomposition analysis schemes. Our results reveal that the E–Cr bonding in the lighter compounds is mainly ionic, while this bonding in the In and Tl complexes is dominated by an orbitalic contribution. We also clarify the origin of deviation of Cp (centroid)-E–Cr angle for the In and Tl complexes using simple molecular orbital arguments and find that the repulsive intermolecular contacts in the crystals are not the real source of this deviation as was claimed. [ABSTRACT FROM AUTHOR]

The nature of the chemical bonds in the EC3+, EC4+, EC5+, and EC6+ species (E = Sc, Y and La) has been examined in depth using a combination of different theoretical strategies. Firstly, exhaustive explorations of the relevant potential energy surfaces using a combination of stochastic and gradient-based search procedures provide us with fan-like structures in singlet and triplet spin states as the most energetically stable configurations. Secondly, the chemical bonding analysis, using natural bond orbital theory, energy decomposition analysis, quantum theory of atoms in molecules, and the adaptive natural density partitioning analysis, indicate that metal–carbon interaction in these species is best described as an intermediate point between ionic and covalent. [ABSTRACT FROM AUTHOR]

Cape gooseberry ( Physalis peruviana ) is an exotic fruit highly valued, however it is a very rich source of polyphenol oxidase (PPO). In this study, Cape gooseberry PPO was isolated and biochemically characterized. The enzyme was extracted and purified using acetone and aqueous two-phase systems. The data indicated that PPO had the highest substrate affinity for chlorogenic acid, 4-methylcatechol and catechol. Chlorogenic acid was the most suitable substrate ( K m = 0.56 ± 0.07 mM and V max = 53.15 ± 2.03 U PPO mL −1 min −1 ). The optimal pH values were 5.5 for catechol and 4-methylcatechol and 5.0 for chlorogenic acid. Optimal temperatures were 40 °C for catechol, 25 °C for 4-methylcatechol and 20 °C for chlorogenic acid. In inhibition tests, the most potent inhibitor was found to be ascorbic acid followed by l -cysteine and quercetin. This study shows possible treatments that can be implemented during the processing of Cape gooseberry fruits to prevent browning. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is an age-related progressive neurodegenerative disorder. Several types of treatments have been tested to block or delay the onset of the disease, but none have been completely successful. Diet, lifestyle and natural products are currently the main scientific focuses. Here, we evaluate the effects of oral administration of the monoterpene linalool (25 mg/kg), every 48 h for 3 months, on aged (21–24 months old) mice with a triple transgenic model of AD (3xTg-AD) mice. Linalool-treated 3xTg-AD mice showed improved learning and spatial memory and greater risk assessment behavior during the elevated plus maze. Hippocampi and amygdalae from linalool-treated 3xTg-AD mice exhibited a significant reduction in extracellular β-amyloidosis, tauopathy, astrogliosis and microgliosis as well as a significant reduction in the levels of the pro-inflammatory markers p38 MAPK, NOS2, COX2 and IL-1β. Together, our findings suggest that linalool reverses the histopathological hallmarks of AD and restores cognitive and emotional functions via an anti-inflammatory effect. Thus, linalool may be an AD prevention candidate for preclinical studies. [ABSTRACT FROM AUTHOR]

Highlights: [•] We report a simple ultrasound (US) method under phase transfer catalysis (PTC) conditions for the Knoevenagel reaction. [•] The US-PTC method is more advantageous than the solvent and catalyst-free microwave irradiation (MWI) method. [•] Reductions were obtained in the reaction times from 13 to 1.5min and increased yields from 50% to 94%. [•] Mild conditions and a convenient US-PTC protocol in organic synthesis are proposed. [•] The US-assisted PTC method allows for carrying out reactions in aqueous mediums. [ABSTRACT FROM AUTHOR]

Inverse carbon-free sandwich structures with formula E2P4 (E=Al, Ga, In, Tl) have been proposed as a promising new target in main-group chemistry. Our computational exploration of their corresponding potential-energy surfaces at the S12h/TZ2P level shows that indeed stable carbon-free inverse-sandwiches can be obtained if one chooses an appropriate Group 13 element for E. The boron analogue B2P4 does not form the D4 h-symmetric inverse-sandwich structure, but instead prefers a D2 d structure of two perpendicular BP2 units with the formation of a double BB bond. For the other elements of Group 13, Al-Tl, the most favorable isomer is the D4 h inverse-sandwich structure. The preference for the D2 d isomer for B2P4 and D4 h for their heavier analogues has been rationalized in terms of an isomerization-energy decomposition analysis, and further corroborated by determination of aromaticity of these species. [ABSTRACT FROM AUTHOR]

New experimental and theoretical data show that the previously reported planar tetracoordinate Sn complexes [Sn(Ph2P(Se)N(Se)PPh2)2] (1-sq) and [Sn(iPr2P(Se)N(Se)PiPr2)2] (2-sq) were not isolated and rather confused with the selenium complexes [Se(Ph2P(Se)N(Se)PPh2)2] (3-sq) and [Se(iPr2P(Se)N(Se)PiPr2)2] (4-sq), respectively. [ABSTRACT FROM AUTHOR]

Six biflavonoids were isolated from G. madruno, one of which, 7''-O-(6''''-acetyl)-glucoside of morelloflavone, is a new compound identified on the basis of 1D, 2D NMR (HMQC and HMBC) spectroscopic methods and chemical evidence. The antioxidant activity of the biflavonoids against low-density lipoprotein (LDL) peroxidation induced with Cu2+, was studied by means of a TBARS assay. The antioxidant potential of a biflavonoid fraction (BF) was also evaluated and correlated with its biflavonoid content. The flavanone-(3→8'')-flavone biflavonoids displayed antioxidant activity, particularly morelloflavone, which was significantly more potent than quercetin, with a CE50 of 12.36 μg/mL. Lipid peroxidation, was also significantly reduced in the presence of the BF (EC50 = 11.85 μg/mL). These results suggest that the BF is an excellent antioxidant. [ABSTRACT FROM AUTHOR]

The stronger antioxidant capacity of the flavonoid quercetin (Q) compared with taxifolin (dihydroquercetin, T) has been the subject of previous experimental and theoretical studies. Theoretical work has focused on the analysis of hydrogen bond dissociation energies (BDE) of the OH phenolic groups, but consider mechanisms that only involve the transfer of one hydrogen atom. In the present work we consider other mechanisms involving a second hydrogen transfer in reactions with free radicals. The relative stability of the radicals formed after the first hydrogen transfer reaction is considered in discussing the antioxidant activity of Q and T. In terms of global and local theoretical reactivity descriptors, we propose that the radical arising from Q should be more persistent in the environment and with the capability to react with a second radical by hydrogen transfer, proton transfer and electron transfer mechanisms. These mechanisms could be responsible of the stronger antioxidant capacity of Q. [ABSTRACT FROM AUTHOR]

The most stable forms of E5Li7+ (E=Ge, Sn, and Pb) have been explored by means of a stochastic search of their potential-energy surfaces by using the gradient embedded genetic algorithm (GEGA). The preferred isomer of the Ge5Li7+ ion is a slightly distorted analogue of the D5 h three-dimensional seven-pointed starlike structure adopted by the lighter C5Li7+ and Si5Li7+ clusters. In contrast, the preferred structures for Sn5Li7+ and Pb5Li7+ are quite different. By starting from the starlike arrangement, corresponding lowest-energy structures are generated by migration of one of the E atoms out of the plane with the a corresponding rearrangement of the Li atoms. To understand these structural preferences, we propose a new energy decomposition analysis based on isomerizations (isomerization energy decomposition analysis (IEDA)), which enable us to extract energetic information from isomerization between structures, mainly from highly charged fragments. [ABSTRACT FROM AUTHOR]

Cancer is a major cause of death and an impediment to increasing life expectancy worldwide. With the aim of finding new molecules for chemotherapeutic treatment of epidemiological relevance, ten alkaloid fractions from Amaryllidaceae species were tested against six cancer cell lines (AGS, BT-549, HEC-1B, MCF-7, MDA-MB 231, and PC3) with HaCat as a control cell line. Some species determined as critically endangered with minimal availability were propagated using in vitro plant tissue culture techniques. Molecular docking studies were carried out to illustrate binding orientations of the 30 Amaryllidaceae alkaloids identified in the active site of some molecular targets involved with anti-cancer activity for potential anti-cancer drugs. In gastric cancer cell line AGS, the best results (lower cell viability percentages) were obtained for Crinum jagus (48.06 ± 3.35%) and Eucharis bonplandii (45.79 ± 3.05%) at 30 µg/mL. The research focused on evaluating the identified alkaloids on the Bcl-2 protein family (Mcl-1 and Bcl-xL) and HK2, where the in vitro, in silico and statistical results suggest that powelline and buphanidrine alkaloids could present cytotoxic activity. Finally, combining experimental and theoretical assays allowed us to identify and characterize potentially useful alkaloids for cancer treatment. [ABSTRACT FROM AUTHOR]

We performed global minimum searches for the B nH n+2 ( n=2-5) series and found that classical structures composed of 2c-2e BH and BB bonds become progressively less stable along the series. Relative energies increase from 2.9 kcal mol−1 in B2H4 to 62.3 kcal mol−1 in B5H7. We believe this occurs because boron atoms in the studied molecules are trying to avoid sp2 hybridization and trigonal structure at the boron atoms, as in that case one 2p-AO is empty, which is highly unfavorable. This affinity of boron to have some electron density on all 2p-AOs and avoiding having one 2p-AO empty is a main reason why classical structures are not the most stable configurations and why multicenter bonding is so important for the studied boron-hydride clusters as well as for pure boron clusters and boron compounds in general. [ABSTRACT FROM AUTHOR]

Abstract: The potential energy surfaces of the Si4Li n (n =1–7) systems have been explored in detail and the global minimum structures were identified. The stability and growth patterns of the title clusters is rationalized in terms of the phenomenological shell model in which the tetrahedral Si4Li4 cluster is a closed shell (20 valence electron) highly stable cluster. Given that the structures reported herein are global minima on their corresponding potential energy surfaces, we propose them as good candidates for experimental detection. [Copyright &y& Elsevier]

Abstract: Vitroceramic powders of Li2O–Al2O3–SiO2 systems (LAS), doped with 1% (LAS:1Ce) and 10% (LAS:10Ce) molar of cerianite (CeO2) were synthesized by means of the gelification technique of metal formates of aluminum and lithium, in the presence of tetraethoxy silane and CeO2. The gels obtained were dried (120°C, 2.5h), calcined (480°C, 5h) and sinterized (1250°C, 30min). The sinterized samples were characterized by X-ray difraction (XRD), scanning electron microscopy (SEM) and microchemical analysis (EDS). There is evidence for a mixture of two phases of 64% β-spodumene (Li2O–Al2O3–4SiO2) and 36% β-eucryptite (Li2O–Al2O3–2SiO2). The LAS:1Ce system was enriched in aluminum, the LAS:10Ce system showed areas of heterogeneous composition; some regions with a shortage of CeO2, while others zones with cerium cumulus. From the microscopy images it was found that CeO2 acts as a densificant agent in LAS system, favoring the sintering in the host. The chemical route and the sintering processes utilized allow the production of samples exhibiting an acceptable linear correlation between total thermoluminescent emission intensity and the irradiation dose when the CeO2 concentration is low (less than 1%), opening the possibility of using this kind of glass-ceramic in dosimetry. [Copyright &y& Elsevier]

Abstract: A comparative study of the thermoluminescence (TL) emission between beta-irradiated lithium aluminosilicates, Li2O–Al2O3–SiO2 (LAS), and beta-irradiated CeO2-doped lithium aluminosilicates, Li2O–Al2O3–SiO2–CeO2 (LAS:Ce), grown by sol-gel technique and preannealed at 1250°C is presented. It is found that doping reinforces the result of preannealing the sample; the incorporation of CeO2 at low concentrations shifts the TL curves towards higher temperatures and increases the total intensity with respect to samples without the dopant. This behavior, together with the fact that CeO2 is a good densification agent, suggests the possibility of using CeO2 to improve the technological properties of LAS. Deconvolution analysis of the thermoluminescence glow curves of doped materials under general order kinetics shows that the relevant temperatures at which the component signals appear are virtually the same as for pure samples. This suggests that CeO2 does not introduce new types of traps, but only changes the population and distribution of impurities responsible for the TL in the original matrix of LAS. Finally, the kinetic parameters for the deconvoluted curves are reported. They corroborate that changes in CeO2 concentration only vary the depth and distribution of the same kind of original traps. [Copyright &y& Elsevier]

Abstract: Ethnobotanical and chemotaxonomical studies for antiparasitic activity of Colombian Annonaceae were carried out. In vitro antiprotozoal activity of 36 extracts obtained from six different species was determined against promastigotes of three Leishmania species, epimastigotes of Trypanosoma cruzi and both chloroquine sensitive (F32) and resistant (W2) Plasmodium falciparum. Cytotoxic activity was evaluated in U-937 cells. Active extracts were selected according their selectivity index (SI). Extracts from Annona muricata, Rollinia exsucca, Rollinia pittieri and Xylopia aromatica were active against Leishmania spp. and Trypanosoma cruzi showing IC50 values lower than 25μg/ml. Hexane extract from Rollinia pittieri leaves was the most selective against Trypanosoma cruzi and Leishmania spp. (IS=10 and 16, respectively). The extracts from Desmopsis panamensis, Pseudomalmea boyacana, Rollinia exsucca and Rollinia pittieri showed good antiplasmodial activity (IC50 <10μg/ml). No correlation between antiplasmodial activity and inhibition of β-hematin production was found. The present study gives specific and useful information about antiprotozoal and cytotoxic activities of some Annonaceae extracts. Results presented here also demonstrate which plants and/or plant parts could be useful in the treatment of leishmaniasis, Chagas’ disease and malaria. [Copyright &y& Elsevier]

Ecuador is an important center of biodiversity for the plant subfamily Amaryllidoideae, known for its important bioactive molecules. This study aimed to assess the chemical and biological potential of four different Amaryllidoideae species collected in Ecuador: Urceolina formosa, Urceolina ruthiana, Clinanthus incarnatus, and Stenomesson aurantiacum. Twenty-six alkaloids were identified in the bulb extracts of these species using GC-MS. The extract of S. aurantiacum exhibited the greatest structural diversity and contained the highest amounts of alkaloids, particularly lycorine and galanthamine. Only for this species, identification of all the alkaloids belonging to this chemical profile was not possible. Six of them remain unidentified. The potential of these three Amaryllidoideae genera against Alzheimer's disease was then evaluated by measuring their AChE and BuChE inhibitory activity, revealing that C. incarnatus and U. formosa (from Sucumbíos province) showed the best results with IC50 values of 1.73 ± 0.25 and 30.56 ± 1.56 µg·mL−1, respectively. Molecular dynamic assays were conducted to characterize the possible interactions that occurs among 2-hydroxyanhydrolycorine and the AChE enzyme, concluded that it is stabilized in the pocket in a similar way to galanthamine. This study expands our understanding of the biodiversity of Amaryllidoideae species from Ecuador, highlighting their potential as source of chemical compounds with pharmaceutical applications. [ABSTRACT FROM AUTHOR]

The balanced cast-in-place cantilever erection method has become a popular construction bridge technique. The main advantages include an industrialized erection technique that prevents the use of intermediate supports and rapid construction. However, the long-term response of this bridge typology is not well understood as long-term deflections due to time-dependent phenomena (such as creep and shrinkage) are significantly simplified in bridge design codes. Existing prediction models commonly used in design tend to underestimate long-term deflections, and as a result, field measurements conducted in newly constructed bridges still report excessive long-term deflections. This paper shows the long-term deflection analysis of a long-span concrete bridge located in Colombia and opened to traffic in 2014. This study is conducted using field data collected within a one-year time interval and modelling results. Further comparisons using field data collected from bridges with similar structural configurations, but opened to traffic in the 90s and 2000s, show that the bridge's current situation is categorized as a major concern. [ABSTRACT FROM AUTHOR]

The fully halogenated or hydrogenated B12X12 2- (X = H, F, Cl, Br and I) clusters are confirmed to be icosahedral. On the other hand, the bare B12 cluster is shownto have a planar structure. A previous study showed that a transformation from an icosahedron to a plane happens when 5 to 7 iodine atoms are remained [P. Farràs et al., Chem. - Eur. J. 18, 13208-13212 (2012)]. Later, the transitionwas confirmed to be seven iodine atoms based on an infrared spectroscopy study [M. R. Fagiania et al., Chem. Phys. Lett. 625, 48-52 (2015)]. In this study, we investigated the effects of different halogen atoms on the opening of the B12 icosahedral cage by means of density functional theory calculations. We found that the halogen elements do not have significant effects on the geometries of the clusters. The computed infrared (IR) spectra show similar representative peaks for all halogen doped clusters. Interestingly, we found a blue-shift in the IR spectra with the increase in the mass of the halogen atoms. Further, we compared the Gibbs free energies at different temperatures for different halogen atoms. The results showthat the Gibbs free energy differences between open and close structures of B12X7- become larger when heavier halogen atoms are presented. This interesting finding was subsequently investigated by the energy decomposition analysis. [ABSTRACT FROM AUTHOR]

The mechanism for the walk rearrangement in Dewar thiophenes has been clarified theoretically by studying the evolution of chemical bonds along the intrinsic reaction coordinates. Substituent effects on the overall mechanism are assessed by using combinations of the ring (R = H, CF3) and traveling (X = S, S = O, and CH2) groups. The origins of fluxionality in the S–oxide of perfluorotetramethyl Dewar thiophene are uncovered in this work. Dewar rearrangements are chemical processes that occur with a high degree of synchronicity. These changes are directly related to the activation energy. [ABSTRACT FROM AUTHOR]

Aims Determine a relationship between the neuroprotective activity and the antioxidant capacity of the Amaryllidaceae alkaloids in a model of Glu excitotoxicity in rat cortical neurons. Materials and methods Was evaluated several alkaloidal fractions isolated from Amaryllidaceae species, a family known to contain neuroprotective alkaloids, in a model of Glu excitotoxicity in rat cortical neurons. In addition, several mechanisms of antioxidant activity were used, and a theoretical study of the antioxidants was performed. Key findings The results of this study suggest that a possible neuroprotective mode of action of the alkaloidal fractions of Eucharis bonplandii (Kunth) Traub bulbs, Eucharis caucana Meerow bulbs, and Clivia miniata Regel leaves, is through their antioxidant activity and ability to stabilize free radicals generated from an excitotoxic process mediated by Glu. The chemical structure characterization and antioxidant activity of the fractions suggest that the phenol and enol groups in the structures of the alkaloids are critical for the stabilization of ROS and RNS. Additionally, the pair of free electrons on the N is spatially close to a hydroxyl group, which benefits the cleavage of this group and, consequently, the stabilization of the generated O . Significance The versatility of the structures of the studied Amaryllidaceae alkaloids suggests that they have potential as neuroprotective agents against an oxidative stimulus. [ABSTRACT FROM AUTHOR]

Stroke is the second cause of death and first cause of physical disability around the world; it affects the brain parenchyma through oxygen deficiency and spreads excitotoxicity. The complexity of the disease has made it difficult to find effective therapies. It is necessary to identify new treatments that effectively act within the narrow therapeutic window but also offer long-term protection poststroke. Our previous work found that oral linalool reversed the hippocampal and peripheral pro-inflammatory phospholipidomic biomarkers in ischemic rats; based on these observations, the "proof of concept" was to demonstrate that intranasal administration of linalool has a faster delivery to the central nervous system to protect it after focal ischemia in Wistar rats. The ischemic animals treated with linalool (25 mg/kg) showed a decrease in infarct volume at 24 h and seven days, and the treated animals had better neurological and motor skills at both poststroke times. Additionally, one month after daily intranasal administration of linalool, the ischemic rats showed improved relearning performance in the Morris water maze test. They also exhibited a reduction in microgliosis and decreased COX2, IL-1Beta and Nrf2 markers in the cerebral cortex and hippocampus. In astrocyte and microglial cultures, linalool reduced pro-inflammation and had a potent effect on microglial cells, generating Nrf2 subcellular redistribution under glutamate excitotoxicity conditions. Together, our findings indicate an acute and chronic recovery after ischemia induced by a daily intranasal puff of linalool, which mainly acts on microglial populations with anti-inflammatory actions. Image 1 • Intranasal linalool reduces infarct volume and recovers neurological function after ischemia. • Linalool intranasal induces anti-inflammatory microglia. • Nrf-2 microglial redistribution under anti-inflammatory context by linalool. [ABSTRACT FROM AUTHOR]

Previous experimental results on the free radical-scavenging properties of boldine, one of the most potent natural antioxidants, suggested that the benzylic hydrogen, neighboring a nitrogen lone electron pair, might be the key to its protective and antioxidant effect, in contrast to the usually assumed labile phenolic hydrogen atoms. Our computations suggest that both boldine and glaucine can undergo two successive hydrogen transfers under attack by an oxidizing radical (from C-6a-H and C-7-H). The hydroxyl groups of boldine could also participate via the HAT mechanism, although to a lesser extent. In the case of quaternary N-methylated derivatives, the sharing of the nitrogen lone pair makes the transfer of the C-6a hydrogen energetically unfeasible, supporting the earlier proposal based on experimental evidence. The hydroxyl groups of boldine and its derivatives could contribute to antioxidant activity via the sequential proton loss electron transfer mechanism, although this would only be relevant at higher pH values. [ABSTRACT FROM AUTHOR]

Acetylcholinesterase (AChE) enzymatic inhibition is an important target for the management of Alzheimer disease (AD) and AChE inhibitors are the mainstay drugs for its treatment. In order to discover new sources of potent AChE inhibitors, a combined strategy is presented based on AChE-inhibitory activity and chemical profiles by GC/MS, together with in silico studies. The combined strategy was applied on alkaloid extracts of five Amaryllidaceae species that grow in Colombia. Fifty-seven alkaloids were detected using GC/MS, and 21 of them were identified by comparing their mass-spectral fragmentation patterns with standard reference spectra in commercial and private library databases. The alkaloid extracts of Zephyranthes carinata exhibited a high level of inhibitory activity (IC 50 = 5.97 ± 0.24 μg/mL). Molecular modeling, which was performed using the structures of some of the alkaloids present in this extract and the three-dimensional crystal structures of AChE derived from Torpedo californica , disclosed their binding configuration in the active site of this AChE. The results suggested that the alkaloids 3-epimacronine and lycoramine might be of interest for AChE inhibition. Although the galanthamine group is known for its potential utility in treating AD, the tazettine-type alkaloids should be evaluated to find more selective compounds of potential benefit for AD. [ABSTRACT FROM AUTHOR]

• G. madruno is a significative source of phenolic compounds (biflavonoids and PIBs). • The epicarp was the richest source of biflavonoids and PIBs (more than 20%). • The regional origin impact significantly the expression of the main metabolites. • The ripeness stage does not influence the expression of quality markers. Garcinia madruno is a neotropical tree characterized by its exotic fruit and its functional compounds. The aim of this study was to evaluate the expression and variability of the chemical markers of G. madruno according to the part of the plant used, the origin and the ripeness stage by applying chemometric tools. A total of 167 samples were evaluated, and 27 compounds were quantified per sample. The expression of amentoflavone, morelloflavone-type biflavonoids and polyisoprenylated benzophenones (PIBs) promoted intergroup differentiation, whereas the expression of GB-2a-type biflavonoids promoted intragroup cluster generation. Epicarp was the main source of biflavonoids and the secondary source of PIBs, with values up to 25% in some individuals. The origin of the fruit significantly impacted the expression of metabolites, whereas the ripeness stage did not. The results indicate that epicarp is a good source of functional compounds and, with appropriately agronomic development, could be improved even more. [ABSTRACT FROM AUTHOR]

Garcinia madruno is rich in antioxidant biflavonoids that could be used to treat oxidative-related diseases. Up to now, its commercial application is challenging due to the poor water solubility of biflavonoids. This work aimed to develop a green and sustainable process to improve the solubility and dissolution rate of G. madruno biflavonoids by the development of 100% natural nanodispersions using peel extracts of this neotropical fruit. Three hydroalcoholic extracts were elaborated with different concentrations of biflavonoids and epicarp proportions. The biflavonoid natural suspensions were obtained by evaporating the ethanol of the different extracts. As a control, suspensions stabilized with commercial surfactants were compared to each other. Two natural nanosuspensions with different concentrations of biflavonoids and one nanosuspension stabilized with commercial surfactants were obtained. All dispersions had submicrometric particle distribution. M3-S nanosuspension (stabilized by commercial stabilizer) was the smallest dispersion with an average particle size of 256.6 nm, whereas natural suspension (NS-1 and NS 2) had better performance in the short-term stability and improved the solubility and dissolution rate until 400% in comparison of M3-S and isolate morelloflavone. Our results demonstrated that it was possible to formulate a biflavonoid suspension using their own plant compounds as natural stabilizers. [ABSTRACT FROM AUTHOR]

Abstract: One of the most serious candidates for safe storage of high hydrogen densities is ammonia borane, AB. Likewise, one of the most versatile catalysts known is gold in the form of atomic clusters. Taking these elements into account, in this work a density functional theory ‐based study about initial activation, detachment, and diffusion of ammonia borane hydrogen on gold tetramer, as a catalyst model, is developed. It was found that the total process is exergonic and that the hydrogen diffusion occurs with very low energy barriers. The process has a hydrogen detachment energy barrier lower than the one of the uncatalyzed AB, and that is easily overcome by the energy expelled in the previous stage of formation of the initial activated species. Additionally, all the process is assisted by the fluxionality of the gold cluster, and occurs via a unique catalytically activated initial species, which contains a three‐center simultaneous interaction at the catalytically activated zone. [ABSTRACT FROM AUTHOR]

Aerial parts of Cuphea calophylla, Tibouchina kingii, and Pseudelephantopus spiralis have been used in Colombian traditional medicine for inflammation. However, the underlying mechanisms that could explain the anti-inflammatory actions remain unknown. This study aimed to elucidate the anti-inflammatory and cytoprotective effects of hydroalcoholic extracts from C. calophylla (HECC), T. kingii (HETK), and P. spiralis (HEPS) in LPS-stimulated THP-1 macrophages. Reactive oxygen species (ROS), nitric oxide (NO), and malondialdehyde (MDA) were monitored as inflammatory and oxidative markers. The inhibition of lipoxygenase (LOX) and cyclooxygenase (COX) activities in a cell-free system were also investigated. Antioxidant activities were determined using standard in vitro methods. All extracts inhibited the NO, ROS, and MDA levels. HETK showed the highest ROS production inhibition and the highest antioxidant values, whereas HETK and HEPS significantly decreased the cytotoxicity mediated by LPS. The release of MDA was reduced significantly by all extracts. Moreover, the catalytic activity of LOX was inhibited by HECC and HETK. HECC was a more potent reducer of COX-2 activity. All extracts effectively suppressed COX-1 activity. In summary, these results suggest that HECC, HEPS, and HETK possess anti-inflammatory properties. Therefore, these plants could provide a valuable source of natural bioactive compounds for the treatment of inflammatory-related diseases. [ABSTRACT FROM AUTHOR]

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that is pathologically characterized by the deposition of β-amyloid (βA) peptides in senile plaques and neurofibrillary tangles in the brain. Flavonoids have recently been used to prevent and treat a variety of neurodegenerative diseases, but little is known about bioflavonoids. In this study, we evaluate whether a biflavonoid fraction (BF) exerts neuroprotective effects on an aged triple transgenic mouse mode of AD (3xTg-AD). Then, 21–24-month-old 3xTg AD mice were i.p. injected with 25 mg/kg of a BF from Garcinia madruno composed of morelloflavone (65%), volkensiflavone (12%), GB 2a (11%), fukugiside (6%) and amentoflavone (0.4%) every 48 h for 3 months. The BF treatment reduced βA deposition in different regions of the brain (the hippocampus, entorhinal cortex and amygdala), reduced βA1-40 and βA1-42 levels, BACE1-mediated cleavage of APP (CTFβ), tau pathology, astrogliosis and microgliosis in the brains of aged 3xTg-AD mice. Although the BF treatment weakly improved learning, animals treated with BF spent more time in the open arms of the elevated plus maze test and displayed greater risk assessment behavior than the control groups. In summary, the BF reverses histopathological hallmarks and reduces emotional disorders in the 3xTg-AD mouse model, suggesting that the biflavonoids from G. madruno represent a potential natural therapeutic option for AD if its bioavailability is improved. [ABSTRACT FROM AUTHOR]

The potential energy surfaces of the singlet and triplet states of the title clusters are computed by DFT methods. [ABSTRACT FROM AUTHOR]

A viable alternative sandwich structure is presented, which does not contain any carbon atom. This D4h ‐ symmetric inverse sandwich instead uses the “carbon ‐ like” phosphorus, which together with heavier elements of Group 13 (E = Al – Tl) forms a stable molecule. Density functional theory computations indicate that the sandwich form is more stable than a D2d isomer of two perpendicular EP2 units (except for E=B), and should be formed exothermically from white phosphorus and E2. For more details, see the Full Paper by M. Swart, G. Merino et al. on page 4583 ff. [ABSTRACT FROM AUTHOR]

Invited for the cover of this issue is the group of Gabriel Merino and Marcel Swart at Cinvestav, Unidad Mérida (Mexico) and the Universitat de Girona (Spain). The image depicts the HOMO of the Al2P4 cluster. Read the full text of the article at . [ABSTRACT FROM AUTHOR]

The interaction among E3 (E=Si, Ge, Sn) clusters and different ligands (L) encompassing five carbon-based donors (cyclic (alkyl)(amino)carbene (cAAC), N-heterocyclic carbene (NHC), saturated NHC (SNHC), mesoionic carbenes (MIC1, and MIC2)), two nitrogen-based donors (trimethylamine and pyridine), and two phosphorous-based donors (phosphinine and trimethylphosphine) in E3(L)3 complexes is explored through DFT computations. Although all carbenes form very strong bonds with E3 clusters, cAAC makes the strongest bond with Si3 and Ge3 clusters, and MIC1 with the Sn3 cluster. Nevertheless, other ligand-bound complexes are also viable at room temperature. This finding indicates that experimentalists may make use of them to synthesize the desired clusters based on precursor availability. The nature of the interaction in E−L bonds is analyzed through natural bond orbital analysis; energy decomposition analysis, in combination with the natural orbital for chemical valence; and adaptive natural density partitioning analysis. The L→E σ-donation and L←E π-back-donation play important roles in making contacts between L and E3 clusters favorable; where the former is significantly more dominant over the latter. [ABSTRACT FROM AUTHOR]

Medicinal plants are recognized by their large number of bioactive secondary metabolites. They have been used to treat several human ailments and are believed to possess many biological activities. However, little is known about the photoprotective and anti-aging properties of important medicinal plants as assessed by integrative studies. To find new bioactive ingredients of cosmetic interest, seven cultivated medicinal plants were systemically evaluated in an integrated manner. Extracts obtained from each species using solvents of diverse dielectric constants were tested on different molecular targets related to skin aging, with a focus on the protection of the main components of the extracellular matrix (ECM). Thus, the inhibition of the enzymes collagenase, elastase and hyaluronidase was determined, and antioxidant properties were evaluated. Subsequently, a photoprotective approach was taken in human dermal fibroblasts (HDF) stimulated with ultraviolet B (UVB)-radiation through the measurement of matrix-metalloproteinases (MMP-1) and procollagen production, as well as intracellular reactive oxygen species (ROS) levels, in pretreatment with bioactive extracts. The species with higher biological activity were chemically characterized through fingerprint analysis by HPLC-DAD and comparison with reference standards. The results showed the ability of some extracts from Rosmarinus officinalis, Thymus vulgaris and Smallanthus sonchifolius to protect the major components of the ECM from UVB irradiation-induced damage. Additionally, useful information, including various bioactivities and the chemical diversity of the extracts of medicinal plants, which could not be acquired from individual assessments of anti-aging activity, was obtained using a holistic anti-aging approach. [ABSTRACT FROM AUTHOR]

The antioxidant activity of nine lichen substances, including methylatrarate (1), methyl haematommate (2), lobaric acid (3), fumarprotocetraric acid (4), sphaerophorin (5), subsphaeric acid (6), diffractaic acid (7), barbatolic acid (8) and salazinic acid (9) has been determined through cyclic voltammetry. The compounds 1–4 presented slopes close to the Nernst constant of 0.059 V, indicating a 2H+/2e− relation between protons and electrons, as long as the compounds 5, 6, 7, 8, and 9 present slopes between 0.037 V and 0.032 V, indicating a 1H+/2e− relation between protons and electrons. These results show a high free radical scavenging activity by means of the release of H+, suggesting an important antioxidant capacity of these molecules. Theoretical calculations of hydrogen bond dissociation enthalpies (BDE), proton affinities (PA), and Proton Transfer (PT) mechanisms, at M06-2x/6-311+G(d,p) level complement the experimental results. Computations support that the best antioxidant activity is obtained for the molecules (3, 4, 5, 6, 7 and 8), that have a carboxylic acid group close to a phenolic hydroxyl group, through hydrogen atomic transfer (HAT) and sequential proton loss electron transfer (SPLET) mechanisms. Additional computations were performed for modelling binding affinity of the lichen substances with CYPs enzymes, mainly CYP1A2, CYP51, and CYP2C9*2 isoforms, showing strong affinity for all the compounds described in this study. • Lichenic substances show enzyme inhibition and antioxidant activity. • Methylatrarate and Methylhaeatommate show antioxidant effect by interaction with CYPs enzymes. • SPLET mechanism could be the most appropriate for study the antioxidant activity. • The electrochemistry measurements provide interesting results with antioxidant activity. [ABSTRACT FROM AUTHOR]

Coffee, a source of chlorogenic acids (CGAs), is recognized for preventing chronic diseases associated with oxidative stress. Therefore, sensitive, selective and easy access methods for the determination of the bioavailability and antioxidant function in vivo are required in clinical studies. The aim of this work was to validate a GC/MS method to quantify caffeic acid (CA) and ferulic acid (FA) and to apply different methodologies to determine the antioxidant capacity of plasma after the acute consumption of 420 mg of CGAs provided by 400 mL of coffee. The intervention was performed in 20 adults (6 men and 14 women) with a mean ± SD age of 35.7 ± 9.0 and body mass index of 22.1 ± 1.6 kg who were assigned to 2 groups: a control group and a group that consumed coffee. The validated analytical GC/MS method was exact, precise and selective. The selected derivatizing reagent was N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide with 1% tertbutyldimethylchlorosilane (MTBSTFA + 1% TBDMSCl). The method was reproducible, and the limit of detection (LOD) was 3 nM for CA and 5 nM for FA. CA and FA were detected in plasma 1 h after coffee intake and were undetectable in the control group. Compared to the baseline values, the antioxidant capacity of plasma significantly increased when it was measured by ferric reducing antioxidant power (FRAP) (6.67%; P < 0.001) and by oxygen radical absorbance capacity (ORAC) (7.16%; P < 0.05). The in vitro and ex vivo experiments on plasma with CA and FA showed a significant increase of the antioxidant activity ( P < 0.05) as well as delay of LDL oxidation ( P < 0.001). The method validated by GC/MS was proposed as an alternative for evaluating the bioavailability of ACG after acute coffee intake. The need for in vitro methodologies was demonstrated to determine the antioxidant activity. [ABSTRACT FROM AUTHOR]

Energy decomposition schemes for MgYH n series, with n = 11,13,15. [Display omitted] • Mg-Y-H systems exhibit high stability and hydrogen storage capacity. • Yttrium-bonded hydrogen molecules are more labile for a dehydrogenation step in comparison to those with scandium. • The QTAIM and EDA-NOCV analysis predict how the H 2 molecules are bonded to the atomic cluster. Magnesium based alloys containing scandium and yttrium are promising materials for hydrogen storage devices due to the hydrogen absorption and desorption kinetic and thermodynamic properties, results showing the reversibility of the hydrogenation reaction and leads to a long-lasting energy source. Nevertheless, to the best of our knowledge, there are no theoretical studies comparing the stability between Y and Sc-doped systems available in the literature. In this contribution, we report an analysis of stability and chemical bonding nature for a series of complexes MgEHn (E = Sc and Y, where n = 10 –16) with the aim to understand the nature of binding between a hydrogen molecule and the core system of the metal blend. The results obtained suggest that yttrium-bonded hydrogen molecules are more labile for a dehydrogenation step in comparison to those with scandium. Additionally, based on QTAIM and EDA-NOCV calculations, we conclude that alloys containing scandium are predicted to be more tightly bonded to H 2 molecules than those with yttrium. Consequently, the dehydrogenation reaction would be more thermodynamically favorable for the latter. [ABSTRACT FROM AUTHOR]

Skin cancer has high rates of mortality and therapeutic failure. In this study, to develop a multi-agent strategy for skin cancer management, the selective cytotoxicity of several alkaloid fractions and pure alkaloids isolated from Amaryllidaceae species was evaluated in melanoma cells. In addition, UVB-stimulated keratinocytes (HaCaT) were exposed to seven alkaloid fractions characterized by GC-MS, and the production of intracellular reactive oxygen species (ROS) and IL-6, were measured to evaluate their photoprotection effects. The Eucharis caucana (bulb) alkaloid fraction (20 μg/ml) had a clear effect on the viability of melanoma cells, reducing it by 45.7% without affecting healthy keratinocytes. This alkaloid fraction and tazettine (both at 2.5 μg/ml) suppressed UVB-induced ROS production by 31.6% and 29.4%, respectively. The highest anti-inflammatory potential was shown by the Zephyranthes carinata (bulb) alkaloid fraction (10 μg/ml), which reduced IL-6 production by 90.8%. According to the chemometric analysis, lycoramine and tazettine had a photoprotective effect on the UVB-exposed HaCaT cells, attenuating the production of ROS and IL-6. These results suggest that Amaryllidaceae alkaloids have photoprotective and therapeutic potential in skin cancer management, especially at low concentrations. [ABSTRACT FROM AUTHOR]

It is known that most of the species growing in high-elevation environments in tropical mountains remain largely unexplored. In particular, little is known from a chemical and biological standpoint. The aim of this study was to conduct a preliminary screening of the effects of selected wild and cultivated Andean plants characterized by small and colorful fruits on collagenase, elastase, hyaluronidase and tyrosinase, along with antioxidant capacity, to identify possible sources of potential anti-aging substances for the development of natural cosmetic products. Sixty-five samples consisting of methanol extracts of the fruits of thirty-five Andean plants at different stages of growth were used in the study. The anti-collagenase, anti-elastase, anti-hyaluronidase and anti-tyrosinase activities were determined by spectrophotometric and fluorometric assays. The antioxidant capacity was measured by oxygen radical absorbance capacity (ORAC) and trolox equivalent anti-oxidant capacity (TEAC) assays. The total phenolic content was determined by the Folin–Ciocalteu method. Liquid–liquid partitions of extracts of interest were performed, and each fraction was tested. The inhibitory activity against skin aging-related enzymes and antioxidant properties has provided evidence for the potential utility of Alchornea triplinervia , Gaultheria erecta , Rubus compactus and Ugni myricoides , which were selected as plants of interest. In addition, the maturity state of fruits alters the properties of extracts in a statistically significant manner. In the vast majority of cases, the immature fruits presented a higher antioxidant capacity and enzymatic inhibitory activity. The extracts, fractions and sub-fractions of G. erecta and U. myricoides fruits showed effective inhibitory activity against skin aging-related enzymes and antioxidant properties, which supports the need to more extensively examine extracts from this plant material. The results of this study illuminated possible ways in which to add value to fruits of thirty-five wild and cultivated Andean plants based on their potential use as anti-aging ingredients in cosmetic formulations. After additional studies of the security and isolation of the active compounds, new cosmetic ingredients useful for anti-aging formulations could be obtained. [ABSTRACT FROM AUTHOR]

There is considerable interest in finding replacements for the synthetic fungicides and preservatives that are currently used to control fungal pathogens; however, any alternative compounds must be safe and must prevent the development of microbial resistance. In this regard, essential oils have received special attention. Protium colombianum Cuatrecasas is an endemic tree found in tropical rainforests and possesses aromatic and resinous characteristics. To date, there have been no reports concerning the chemistry of this species, which belongs to a genus that represents an interesting source of essential oils that are occasionally used as antimicrobial agents. Therefore, the chemical composition of the essential oils found in P. colombianum collected from two life zones over a five-month period was analyzed using gas-chromatography/mass-spectrometry. A total of 92 components, comprising 97.7-99.9 % of the total composition, were identified based on their mass spectra and the retention indices. Precedence markers were identified for each life zone, and seasonality affected the samples from one life zone when rainfall was maximum. The in vitro activity against Fusarium oxysporum isolates from carnation and chrysanthemum, as well as a Fusarium solani isolate from chrysanthemum, was tested by determining the minimum inhibitory concentration. Assays using essential oils and control substances showed that terpenoid and phenolic compounds are mainly responsible for the observed anti-fungal activity. These results suggest that P. colombianum essential oils exhibit cytotoxicity against Fusarium isolates and that the search for new sources of anti-fungal essential oils should include sources that contain different ratios of terpenoid and phenolic compounds. [ABSTRACT FROM AUTHOR]

Phenol is one of the worst contaminants at date, and its degradation has been a crucial task over years. Here, the decomposition process of phenol, in a Fenton reaction, is described. Using scavengers, it was observed that decomposition of phenol was mainly influenced by production of hydroxyl radicals. Experimental and theoretical activation energies ( E a ) for phenol oxidation intermediates were calculated. According to these E a , phenol decomposition is a two-step reaction mechanism mediated predominantly by hydroxyl radicals, producing a decomposition yield order given as hydroquinone > catechol > resorcinol. Furthermore, traces of reaction derived acids were detected by HPLC and GS-MS. [ABSTRACT FROM AUTHOR]