Thomas Jakschitz

Vapours of US and EU Market Leader Electronic Cigarette Brands and Liquids Are Cytotoxic for Human Vascular Endothelial Cells

The present study was conducted to provide toxicological data on e-cigarette vapours of different e-cigarette brands and liquids from systems viewed as leaders in the e-cigarette market and to compare e-cigarette vapour toxicity to the toxicity of conventional strong high-nicotine cigarette smoke. Using an adapted version of a previously constructed cigarette smoke constituent sampling device, we collected the hydrophilic fraction of e-cigarette vapour and exposed human umbilical vein endothelial cells (HUVECs) to the mixture of compounds present in the vapour of 4 different single-use e-cigarettes, 6 different liquid vapours produced by the same refillable e-cigarette, and one e-cigarette with an exchangeable liquid cartridge. After incubation of cells with various concentrations and for various periods of time we analysed cell death induction, proliferation rates, the occurrence of intra-cellular reactive oxygen species, cell morphology, and we also measured e-cigarette heating coil temperatures. Overall, conventional cigarette smoke extract showed the most severe impact on endothelial cells. However, some e-cigarette vapour extracts showed high cytotoxicity, inhibition of cell proliferation, and alterations in cell morphology, which were comparable to conventional high-nicotine cigarettes. The vapours generated from different liquids using the same e-cigarette show substantial differences, pointing to the liquids as an important source for toxicity. E-cigarette vapour-mediated induction of oxidative stress was significant in one out of the 11 analysed vapours. There is a high variability in the acute cytotoxicity of e-cigarette vapours depending on the liquid and on the e-cigarettes used. Some products showed toxic effects close to a conventional high-nicotine cigarette. Liquid nicotine, menthol content, and the formation of acute intracellular reactive oxygen species do not seem to be the central elements in e-cigarette vapour toxicity.

The catalytic effect of l- and d-histidine on alanine and lysine peptide formation

A starting phase of chemical evolution on our ancient Earth around 4 billion years ago was the formation of amino acids and their combination to peptides and proteins. The salt-induced peptide formation (SIPF) reaction has been shown to be appropriate for this condensation reaction under moderate and plausible primitive Earth conditions, forming short peptides from amino acids in aqueous solution containing sodium chloride and Cu(II) ions. In this paper we report results about the formation of dialanine and dilysine from their monomers in this reaction. The catalytic influence of l- and d-histidine dramatically increases dialanine yields when starting from lower alanine concentrations, but also dilysine formation is markedly boosted by these catalysts. Attention is paid to measurable preferences for one enantiomeric form of alanine and lysine in the SIPF reaction. Alanine, especially, shows stereospecific behaviour, mostly in favour of the l-form.

Poly(N-vinylimidazole/ethylene glycol dimethacrylate) for the purification and isolation of phenolic acids.

In this study we report the novel polymeric resin poly(N-vinyl imidazole/ethylene glycol dimethacrylate) for the purification and isolation of phenolic acids. The monomer to crosslinker ratio and the porogen composition were optimized for isolating phenolic acids diluted in acetonitrile at normal phase chromatography conditions, first. Acetonitrile serves as polar, aprotic solvent, dissolving phenolic acids but not interrupting interactions with the stationary phase due to the approved Hansen solubility parameters. The optimized resin demonstrated high loading capacities and adsorption abilities particularly for phenolic acids in both, acetonitrile and aqueous solutions. The adsorption behavior of aqueous standards can be attributed to ion exchange effects due to electrostatic interactions between protonated imidazole residues and deprotonated phenolic acids. Furthermore, adsorption experiments and subsequent curve fittings provide information of maximum loading capacities of single standards according to the Langmuir adsorption model. Recovery studies of the optimized polymer in the normal-phase and ion-exchange mode illustrate the powerful isolation properties for phenolic acids and are comparable or even better than typical, commercially available solid phase extraction materials. In order to prove the applicability, a highly complex extract of rosemary leaves was purified by poly(N-vinyl imidazole/ethylene glycol dimethacrylate) and the isolated compounds were identified using UHPLC-qTOF-MS.

Salt-Induced Peptide Formation in Chemical Evolution: Building Blocks Before RNA – Potential of Peptide Splicing Reactions

From a chemical point of view, it seems likely that peptides and smaller proteins were the first biomolecules which may have formed on the prebiotic Earth. In the presence of sodium chloride and copper ions, amino acids are readily connected to oligomers via the Salt-Induced Peptide Formation (SIPF) reaction mechanism in aqueous solution under locally conceivable primitive Earth conditions. The SIPF reaction shows some specific properties suggesting a close relationship to modern life forms, like a preference for α-amino acids and even stereospecific differentiation in favour of the l-forms of some amino acids. Furthermore, the amino acid sequences which are preferably formed by this reaction can still be found with a probability much above average in proteins of still existing life forms, like archaea and other prokaryotic cells. Once formed, even short peptides have a number of highly interesting abilities pointing towards possible further evolutionary pathways: chain elongation on the surface of clay minerals, formation of nanovesicles with membrane-like structure, autocatalytic self-replication from fragments, stabilisation of phosphate ions against precipitation, etc.

The Origin of First Peptides on Earth: From Amino Acids to Homochiral Biomolecules

From general considerations about the formation of first biomolecules in a primordial Earth scenario, it is concluded that amino acids, peptides and proteins are the compounds with the highest probability to be formed first. Consequently, possible formation reactions for these compounds and related simulation experiments are presented, in particular Miller-type experiments for the synthesis of amino acids and condensation reactions leading to peptides. Among the latter, especially the salt-induced peptide formation (SIPF) reaction is discussed, as it is based on a very simple and variable scenario, and offers a number of explanations for phenomena still observed in present life forms. This pertains to non-statistical amino acid sequences, the type of preferably used amino acids and to the l-homochirality of proteins in all life forms on Earth.