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Background: Collagenase, hyaluronidase, elastase, and tyrosinase enzymes are overexpressed and overactive in the skin aging process and hydrolyze the components of the dermal extracellular matrix (ECM) of the skin; these enzymes produce the clinical framework of aging, which includes skin dryness, hyperpigmentation, wrinkles, and inelasticity. Aims: The aim of this study was to explore the potential use of waste from two Argentine native fruits, namely Ziziphus mistol, and red and orange varieties of Solanum betaceum, as sources of bioactive compounds. Methods: Phenolic enriched extracts (PEE) from waste of Z. mistol and S. betaceum were obtained, and their total contents of phenolics and flavonoids were evaluated. The bioactive properties of the extracts were analyzed by measuring their antioxidant capacity and the inhibitory activity on collagenase, hyaluronidase, elastase, and tyrosinase enzymes. Results: The increased ability to inhibit the collagenase was demonstrated by the PEE of Z. mistol seeds and peel, while the enzyme elastase was mostly inhibited by extracts of S. betaceum skin. Z. mistol seed extract was the most active to inhibit hyaluronidase, reaching 96% inhibition at a concentration of 100 μg GAE/mL. The most active extracts to inhibit the tyrosinase enzyme were obtained from the peel of two varieties of chilto fruits, orange and red, and the mistol seed. Conclusions: The results obtained suggest that Z. mistol and S. betaceum waste may be considered as a source of bioactive phenolics. Here, Argentine native fruits waste is presented as a most promising alternative in cosmetic products, with future uses such as hydrogels, creams, or lotions. [ABSTRACT FROM AUTHOR]

Background: The overexposure to sun ultraviolet (UV) radiation produce photoaging by effect of free radicals on lipid, protein, and nucleic acid or by direct activation of responsible enzymes of cleavage of extracellular matrix components (EMC). Aims: To develop new anti‐photoaging agents, the anti‐aging activity of four "jarillas" standardized extracts from Argentina (Zuccagnia punctata Cav.,Larrea divaricata Cav.,Larrea cuneifolia Cav., and Larrea nitida Cav.) were examined. Methods: The effect on the activity and expression of enzymes related to photoaging (collagenase, hyaluronidase, elastase, tyrosinase) and the antioxidant capacity of four "jarillas" extracts were examined. Results: The results suggest that "jarillas" extracts could protect EMC by inhibition of skin aging‐related enzymes and suppression of the expression of metalloproteinases (MMP‐1) in human skin fibroblasts from photoinduced damage. Modulation of MMP‐1 expression induced by UV radiation in human skin cells could be associated, at least in part, with the ROS scavenging capacity of "jarilla" extracts. The extract of Z punctata was more active than Larrea species extracts in all the trials. The activity of Z punctata and Larrea extracts could be ascribed to chalcones and lignans, major constituents of "jarillas," respectively. Conclusions: The results obtained would indicate the potential of these adapted species to live in arid zones of Argentina, exposed to high ultraviolet radiation in production of cosmetic products and justify the promotion of their sustainable use and the development of crops. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Enzymatic inhibition of acetylcholinesterase (AChE) is an essential therapeutic target for the treatment of Alzheimer's disease (AD) and AChE inhibitors are the first‐line drugs for it treatment. However, butyrylcholinesterase (BChE), contributes critically to cholinergic dysfunction associated with AD. Thus, the development of novel therapeutics may involve the inhibition of both cholinesterase enzymes. Objective: To evaluate, in an integrated bioguided study, cholinesterases alkaloidal inhibitors of Amaryllidaceae species. Methodology: The proposed method combines high‐performance thin‐layer chromatography (HPTLC) with data analysis by densitometry, enzymatic bioautography with different AChEs and BChEs, the detection of bioactive molecules through gas chromatography mass spectrometry (GC–MS) analysis of spots of interest, and theoretical in silico studies. Results: To evaluate the bioguided method, the AChE and BChE inhibitory activities of seven Amaryllidaceae plant extracts were evaluated. The alkaloid extracts of Eucharis bonplandii exhibited a high level of inhibitory activity (IC50 = 0.72 ± 0.05 μg/mL) against human recombinant AChE (hAChE). Regarding human serum BChE (hBChE), the bulb and leaf extracts of Crinum jagus had the highest activity (IC50 = 8.51 ± 0.56 μg/mL and 11.04 ± 1.21 μg/mL, respectively). In the HPTLC spots with high inhibitory activity, several alkaloids were detected using GC–MS, and some of these alkaloids were identified. Galanthamine, galanthamine N‐oxide and powelline should be the most prominent inhibitors of substrate accommodation in the active site of the Torpedo californica AChE (TcAChE), hAChE and hBChE enzymes. Conclusions: These results are evidence of the chemical relevance of the Colombian's Amaryllidaceae species for the inhibition of cholinesterases and as potent sources for the palliative treatment of AD. Copyright © 2017 John Wiley & Sons, Ltd. [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]

Abstract: The viability of noble gas axled boron nanowheels NgnM©B10− (Ng=Ar–Rn; M=Nb, Ta; n=1, 2) is explored by ab initio computations. In the resulting Ng2–M complexes, the Ng‐M‐Ng nanorod passes through the center of the B10− ring, providing them with an inverse sandwich‐like structure. While in the singly Ng bound analogue, the Ng binding enthalpy Hb at 298 K ranges from 2.5 to 10.6 kcal mol−1, in doubly Ng bound cases it becomes very low for the Ng2M©B10−→Ng+NgM©B10− dissociation channel, except for the case of Rn, for which the corresponding Hb values are 3.4 (Nb) and 4.0 kcal mol−1 (Ta). For a given Ng, Ta has slightly higher Ng‐binding ability than Nb. The corresponding free‐energy changes indicate that these systems, particularly the Xe and Rn complexes, are good candidates for experimental realization in a low‐temperature matrix. The Ng−M bonds were found to be covalent in nature, as reflected in their large Wiberg bond indices, formation of a 2c–2e σ orbital between Ng and M centers in natural bond orbital and adaptive natural density partitioning (AdNDP) analyses, and the short Ng−M distances. Energy decomposition analysis and a study on the natural orbitals for chemical valence show that the Ng−M contact is supported mainly by the orbital and electrostatic interactions, with almost equal contributions. Although both the Ng→M σ donation and Ng←M π backdonation play roles in the origin of orbital interaction, the former is significantly dominant over the latter. Further, AdNDP analysis indicates that the doubly aromatic character (both σ and π) in MB10− clusters is not perturbed by the interaction with Ng atoms. [ABSTRACT FROM AUTHOR]

Abstract: Although the noble gas (Ng) compounds with either Ng−C or Ng−N bonds have been reported in the literature, compounds containing both bonds are not known. The first set of systems having a C‐Ng‐N bonding unit is predicted herein through the analysis of stability and bonding in the NCNgNSi (Ng=Kr–Rn) family. While the Xe and Rn inserted analogues are thermochemically stable with respect to all dissociation channels, but for the one producing CNSiN and free Ng, NCKrNSi has another additional three‐body dissociation channel, NCKrNSi→CN+Kr+NSi, which is exergonic by −9.8 kcal mol−1 at 298 K. This latter dissociation can be hindered by lowering the temperature. Moreover, the NCNgNSi→Ng+CNSiN dissociation is also kinetically prohibited by a quite high free energy barrier ranging from 25.2 to 39.3 kcal mol−1, with a gradual increase in going from Kr to Rn. Therefore, these compounds are appropriate candidates for experimental realization. A detailed bonding analysis by employing natural bond orbital, electron density, energy decomposition, and adaptive natural density partitioning analyses indicates that both Ng−N and C−Ng bonds in the title compounds are covalent in nature. In fact, the latter analysis indicates the presence of delocalized 3c–3e σ‐bond within the C‐Ng‐N moiety and a totally delocalized 5c–2e σ‐bond in these compounds. This is an unprecedented bonding characteristic in the sense that the bonding pattern in Ng inserted compounds is generally represented as the presence of covalent bond in one side of Ng, and the ionic interaction in the other side. Further, the dissociation of Ng from NCNgNSi facilitates the formation of a higher energy isomer of NCNSi, CNSiN, which cannot be formed from bare NCNSi as such, because of the very high free energy barrier associated with the isomeric transformation. Therefore, in the presence of Ng atoms it might be possible to detect the high energy isomer. [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]

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]

BACKGROUND Cape gooseberry ( Physalis peruviana) is an exotic fruit highly valued for its organoleptic properties and bioactive compounds. Considering that the presence of phenolics and ascorbic acid could contribute to its functional capacity, it is important to investigate the quality parameters, bioactive contents and functional properties with respect to genotype and ripening time. In this study the genotype effect was evaluated in 15 cultivars for two different harvest times. Changes during maturation were recorded in two commercial cultivars within seven levels of maturity. RESULTS Multivariate statistical analysis suggested that phenolic content and ORAC value were mainly affected by harvest time and that ascorbic acid content and DPPH level were mainly affected by genotype. In addition, acidity, phenolic content, ORAC value and inhibition of LDL oxidation decreased with maturity, but soluble solids content, ascorbic acid content, β-carotene content and DPPH-scavenging activity were higher in mature fruits. CONCLUSION The phenolic content, ascorbic acid content and antioxidant properties of Cape gooseberry fruit were strongly affected by cultivar, harvest time and maturity state. Consequently, the harvest time must be scheduled carefully to gain the highest proportion of bioactive compounds according to the specific cultivar and the environment where it is grown. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The potential energy surfaces (PES) of a series of gold-boron clusters with formula Au nB ( n = 1-8) and Au mB2 ( m = 1-7) have been explored using a modified stochastic search algorithm. Despite the complexity of the PES of these clusters, there are well-defined growth patterns. The bonding of these clusters is analyzed using the adaptive natural density partitioning and the natural bonding orbital analyses. Reactivity is studied in terms of the molecular electrostatic potential. © 2014 Wiley Periodicals, Inc. [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]

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]

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]

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