Untersuchung von Fetten und ?len

Ohne Zusammenfassung     

MALDI‐MS of flavonoids: a systematic investigation of ionization and in‐source dissociation mechanisms

Matrix assisted laser desorption ionization (MALDI) is a technique widely employed in the analysis of proteins and peptides, and nowadays it has also been applied to small molecules. There is little significant information regarding the in‐source dissociation processes on MALDI for natural products. Twenty‐six flavonoids (flavanones, flavones and flavonols) were analyzed by MALDI using different methods (with different matrices) and without matrix to comprehend the in‐source reactions and establish good analysis methods for these compounds. Depending on the class, structure and the laser intensity applied, methoxylated flavonoid aglycones can eliminate methyl radicals (˙CH₃) in the source, such as flavonols, but lithium 2,4‐dihydroxybenzoate matrix suppresses the ˙CH₃ eliminations and retro‐Diels–Alder cleavages in the source. All of the flavonoid O‐glycosides evaluated herein eliminated the sugar in source, even in the presence of the matrix, and its product radical ions ([M‐H‐sugar]^?˙) were observed in the negative mode. The flavone C‐glycosides suffered intense dissociation, which was reduced by the addition of a matrix and the application of low laser intensity, mainly in the negative mode. Depending on the hydroxyl substituents, the [M‐H‐H]^?˙ ion was observed with variable relative intensity in the spectra. Copyright © 2015 John Wiley & Sons, Ltd.     

Lipoxygenase inhibitory activity of Cuspidaria pulchra and isolated compounds

This work evaluated the in vitro inhibitory activity of the crude ethanolic extract from the aerial parts of Cuspidaria pulchra (Cham.) L.G. Lohmann against 15-lipoxygenase (15-LOX). The bioassay-guided fractionation of the n-butanol fraction, which displayed the highest activity, led to the isolation of three compounds: caffeoylcalleryanin (1), verbascoside (2) and 6-hydroxyluteolin-7-O-β-glucoside (3). Assessment of the ability of the isolated compounds to inhibit 15-LOX revealed that compounds 1, 2 and 3 exerted strong 15-LOX inhibitory activity; IC₅₀ values were 1.59, 1.76 and 2.35 μM respectively. The XTT assay showed that none of the isolated compounds seemed to be significantly toxic.     

Sun protection Provided by Regulation School Uniforms in Australian Schools: An Opportunity to Improve Personal Sun protection During Childhood

Childhood sun exposure is linked to excessive pigmented mole development and melanoma risk. Clothing provides a physical barrier, protecting skin from ultraviolet radiation (UVR). Extending sleeves to elbow length and shorts to knee length has been shown to significantly reduce mole acquisition in preschoolers from tropical Queensland. We used publicly available uniform images and guidelines from primary schools in Townsville (latitude 19.25°S, n = 43 schools), Cairns (16.87°S, n = 46) and the Atherton Tablelands (17.26°S, n = 23) in tropical Australia to objectively determine the body surface proportion covered by regulation school uniforms. Uniforms of nongovernment, large (≥800 students), urban, educationally advantaged schools with comprehensive sun protection policies covered more skin than those of government schools (63.2% vs 62.0%; P < 0.001), smaller schools (63.4% vs 62.3%; P = 0.009), rural (62.7% vs 61.9%; P = 0.002) and educationally disadvantaged schools (62.8% vs 62.3%; P < 0.001) with underdeveloped sun protection policies (62.8% vs 62.2%; P = 0.002). Overall, SunSmart and non‐SunSmart school uniforms covered identical body surface proportions (62.4%, P = 0.084). Although wearing regulation school uniforms is mandatory at most Australian primary schools, this opportunity to improve children's sun protection is largely overlooked. Recent evidence suggests that even encouraging minor alterations to school uniforms (e.g. slightly longer sleeves/dresses/skirts/shorts) to increase skin coverage may reduce mole acquisition and melanoma risk, especially in high‐risk populations.     

Liquid-phase epitaxy of multicomponent layer-based porous coordination polymer thin films of [M(L)(P)0.5] type: importance of deposition sequence on the oriented growth

The progressive liquid-phase layer-by-layer (LbL) growth of anisotropic multicomponent layer-based porous coordination polymers (PCPs) of the general formula [M(L)(P)(0.5)] (M: Cu(2+), Zn(2+); L: dicarboxylate linker; P: dinitrogen pillar ligand) was investigated by using either pyridyl- or carboxyl-terminated self-assembled monolayers (SAMs) on gold substrates as templates. It was found that the deposition of smooth, highly crystalline, and oriented multilayer films of these PCPs depends on the conditions at the early growth cycles. In the case of a two-step process with an equimolar mixture of L and P, growth along the [001] direction is strongly preferred. However, employing a three-step scheme with full separation of all components allows deposition along the [100] direction on carboxyl-terminated SAMs. Interestingly, the growth of additional layers on top of previously grown oriented seeding layers proved to be insensitive to the particular growth scheme and full retention of the initial orientation, either along the [001] or [100] direction, was observed. This homo- and heteroepitaxial LbL growth allows full control over the orientation and the layer sequence, including introduction of functionalized linkers and pillars.     

Catalytic asymmetric aza-Darzens reaction with a vaulted biphenanthrol magnesium phosphate salt

Conditions for a catalytic asymmetric aza-Darzens aziridine synthesis mediated by a vaulted biphenanthrol (VAPOL) magnesium phosphate salt is described. Using simple substrates, this methodology explores the scope and reactivity of a new magnesium catalyst for an aziridination reaction capable of building chirality and complexity simultaneously.     

Elaboration of hybrid nanocluster materials by solution chemistry

The [(M₆L₁₂ⁱ)L₆^a]ⁿ⁻ and [(M₆L₈ⁱ)L₆^a] units (a = apical, i = inner) constitute the basic building blocks in the octahedral cluster chemistry. Nano-sized metallic clusters are easily obtained by solid state synthesis with transition elements associated with halogen or chalcogen. The intrinsic properties of M₆ cluster units—one or two electron reversible redox process, magnetism and luminescence—depend on the nature of the metal and ligands. The solubilisation of M₆ solid state compounds provides [(M₆L₁₂ⁱ)L₆^a]ⁿ⁻ or [(M₆L₈ⁱ)L₆^a]ⁿ⁻ building blocks with individual properties that can be further used for the design of hybrid organic/inorganic materials. Several examples of solid state precursors are presented as well as substitution reactions of apical ligands in solution. Indeed, hexacyano M₆ clusters are obtained by direct reaction of solid state precursors in aqueous KCN solutions. Low dimensional frameworks are subsequently obtained by recrystallisation of hexacyano M₆ clusters with transition elements. The functionalisation of cluster proceeds in two steps. The first one consists in the replacement of apical halogens of cluster unit precursors by labile groups as CF₃SO₃ (triflate) or solvent molecules after solution reaction. The second one consists in the substitution of the labile groups by functionalised phenolate or pyridine ligands.