Molecules2016, 21(9), 1154; doi:10.3390/molecules21091154 (registering DOI) - published 30 August 2016 Show/Hide Abstract
Abstract: Measuring the antioxidant capacity of foods is essential, as a means of quality control to ensure that the final product reaching the consumer will be of high standards. Despite the already existing assays with which the antioxidant activity is estimated, new, faster and low cost methods are always sought. Therefore, we have developed a novel colorimeter and combined it with a slightly modified DPPH assay, thus creating a kit that can assess the antioxidant capacity of liquids (e.g., different types of coffee, beer, wine, juices) in a quite fast and low cost manner. The accuracy of the colorimeter was ensured by comparing it to a fully validated Hitachi U-1900 spectrophotometer, and a coefficient was calculated to eliminate the observed differences. In addition, a new, user friendly software was developed, in order to render the procedure as easy as possible, while allowing a central monitoring of the obtained results. Overall, a novel kit was developed, with which the antioxidant activity of liquids can be measured, firstly to ensure their quality and secondly to assess the amount of antioxidants consumed with the respective food.
Molecules2016, 21(9), 1151; doi:10.3390/molecules21091151 (registering DOI) - published 30 August 2016 Show/Hide Abstract
Abstract: Three organotin complexes containing furosemide as a ligand (L), Ph3SnL, Me2SnL2 and Bu2SnL2, were synthesized and characterized. Octahedral geometry was proposed for the Me2SnL2 and Bu2SnL2, while the Ph3SnL complex has trigonal bipyramid geometry. The synthesized organotin complexes (0.5% by weight) were used as additives to improve the photostability of poly(vinyl chloride), PVC, (40 μm thickness) upon irradiation. The changes imposed on functional groups, weight loss and viscosity average molecular weight of PVC films were monitored. The experimental results show that the rate of photodegradation was reduced in the presence of the organotin additives. The quantum yield of the chain scission was found to be low (9.8 × 10−7) when Ph3SnL was used as a PVC photostabilizer compared to controlled PVC (5.18 × 10−6). In addition, the atomic force microscope images for the PVC films containing Ph3SnL2 after irradiation shows a smooth surface compared to the controlled films. The rate of PVC photostabilization was found to be highest for Ph3SnL followed by Bu2SnL2 and Me2SnL2. It has been suggested that the organotin complexes could act as hydrogen chloride scavengers, ultraviolet absorbers, peroxide decomposers and/or radical scavengers.
Molecules2016, 21(9), 1155; doi:10.3390/molecules21091155 (registering DOI) - published 30 August 2016 Show/Hide Abstract
Abstract: Novel silylium ions with N-heterocyclic imines were successfully synthesized. The reaction of trimethylsilyl imidazolin-2-imine Me3SiNIPr (NIPr = bis(2,6-diisopropylphenyl)-imidazolin-2-imino) with B(C6F5)3 leads to dimeric imino-substituted silylium ions through a methyl group abstraction on the silicon atom. Meanwhile, the intermolecular imino-coordinated silylium ion is formed by using the less sterically crowded imine Me3SiNItBu (NItBu = bis(tert-butyl)-imidazolin-2-imino). Furthermore, the treatment of dimethylchlorosilane Me2(Cl)SiNIPr with AgOTf affords the contact ion pair Me2(OTf)SiNIPr by substitution of the chloride. A novel complex with the formula [Me2(DMAP)SiNIPr][OTf] was prepared by coordination with 4-dimethylamino-pyridine (DMAP). In the solid state, the DMAP adduct [Me2(DMAP)SiNIPr][OTf] contains a distinct [Me2(DMAP)SiNIPr]+ moiety.
Molecules2016, 21(9), 1153; doi:10.3390/molecules21091153 (registering DOI) - published 30 August 2016 Show/Hide Abstract
Abstract: The purpose of this study was to explore a series of Passerini reactions on a biocatalytically derived enantiopure azetidine-2-carboxyaldehyde in order to obtain, in a diastereoselective manner, polyfunctionalised derivatives having the potential to be cyclized to chiral bridged bicyclic nitrogen heterocycles. While diastereoselectivity was poor under classical Passerini conditions, a significant increase of diastereoselectivity (up to 76:24) was gained by the use of zinc bromide as promoter. The methodology has a broad scope and yields are always good.
Molecules2016, 21(9), 1152; doi:10.3390/molecules21091152 (registering DOI) - published 30 August 2016 Show/Hide Abstract
Abstract: Four new mexicanolide-type limonoids 1–4, along with two known limonoids 5–6, were isolated from the ethanolic extracts of roots of the Traditional Chinese Medicine Trichilia sinensis. Their structures were unambiguously determined by analysis of spectroscopic data, including 1D and 2D NMR as well as MS, and by comparison with literature data. In addition, the acetylcholinesterase (AChE) inhibitory activity of compounds 1–6 was evaluated by the Ellman method. All these compounds showed weak AChE inhibitory activity, with the inhibition percentages ranging from 18.5% to 27.8%.
Molecules2016, 21(9), 1150; doi:10.3390/molecules21091150 (registering DOI) - published 30 August 2016 Show/Hide Abstract
Abstract: The antioxidant and antibacterial activities of wood vinegar from Litchi chinensis, and its components have been studied. The chemical compositions of wood vinegar were analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 17 chemical compounds were identified, representing 83.96% of the compositions in the wood vinegar. Three major components, included 2,6-dimethoxyphenol (syringol, 29.54%), 2-methoxyphenol (guaiacol, 12.36%), and 3,5-dimethoxy-4-hydroxytoluene (11.07%), were found in the wood vinegar. Antioxidant activities of the acids were investigated from the aspects of 1,1-Diphyl-2-picrylhydrazyl (DPPH) free radicals scavenging capacity, superoxide anion radical scavenging capacity, and reducing power. The pyroligneous acid exhibited high antioxidant activity which was comparable to the reference standards (vitamin C and butylated hydroxyl toluene) at the same dose with IC50 values of 36.5 ppm calculated by the DPPH radical scavenging assay, 38.38 g Trolox equivalent/100 g DW by the trolox equivalent antioxidant capacity (TEAC) assay, and 67.9 by the reducing power analysis. Antibacterial activity was evaluated using the disc diffusion and microdilution methods against a group of clinically antibiotic resistant isolates. The major components exhibited broad spectrum inhibition against all the bacterial strains with a range of disc inhibition zoon between 15–19 mm. The minimum inhibition concentration and minimum bactericide concentration against the test strains was ranging in 0.95–3.80 μL/100 μL and 1.90–3.80 μL/100 μL, respectively. Most of the antibiotic resistant strains were more susceptible to the wood vinegar than the non-antibiotic resistant strain except the strain of ornithine resistant Staphylococcus aureus. Based on the chemical profile, it was considered that the strongest antioxidant and antibacterial activity of Litchi chinensis wood vinegar was due to its highly phenolic compositions. This study revealed that the Litchi chinensis wood vinegar is valuable to develop as alternative food antioxidant and antibiotics.