Molecular products from the thermal degradation of glutamic acid

One Step up the Ladder of Prebiotic Complexity: Formation of Nonrandom Linear Polypeptides from Binary Systems of Amino Acids on Silica

Evidence for the formation of linear oligopeptides with nonrandom sequences from mixtures of amino acids coadsorbed on silica and submitted to a simple thermal activation is presented. The amino acid couples (glutamic acid+leucine) and (aspartic acid+valine) were deposited on a fumed silica and submitted to a single heating step at moderate temperature. The evolution of the systems was characterized by X-ray diffraction, infrared spectroscopy, thermosgravimetric analysis, HPLC, and electrospray ionization mass spectrometry (ESI-MS). Evidence for the formation of amide bonds was found in all systems studied. While the products of single amino acids activation on silica could be considered as evolutionary dead ends, (glutamic acid+leucine) and, at to some extent, (aspartic acid+valine) gave rise to the high yield formation of linear peptides up to the hexamers. Oligopeptides of such length have not been observed before in surface polymerization scenarios (unless the amino acids had been deposited by chemical vapor deposition, which is not realistic in a prebiotic environment). Furthermore, not all possible amino acid sequences were present in the activation products, which is indicative of polymerization selectivity. These results are promising for origins of life studies because they suggest the emergence of nonrandom biopolymers in a simple prebiotic scenario.

Constituents of "teabacco": A forensic analysis of cigarettes made from diverted nicotine replacement therapy lozenges in smoke-free prisons

Following the implementation of prison smoke-free policies, there have been reports of prisoners creating substitute cigarettes made from nicotine replacement therapy patches or lozenges infused with tea leaves ("teabacco"). No studies have analyzed the chemical constituents of teabacco made from nicotine lozenges, so as to document any potential related health hazards. Teabacco samples were made by a participant who reported creating teabacco while incarcerated in a smoke-free prison in Queensland, Australia, and the process was video-recorded for replication in a laboratory. A simple linear smoking system captured the teabacco smoke for analysis. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was used to analyze elemental composition and gas chromatography coupled with a mass spectrometer (GC-MS) analyzed the captured smoke using the National Institute of Standards and Technology mass spectral library. Analyses determined that quantities of copper, aluminum, and lead concentrations, and levels of inhaled total particulate matter, were above recommended guidelines for safe ingestion. Analysis of teabacco smoke using GC-MS identified potentially toxic compounds catechol and nicotine. However, our findings show that smoking this form of teabacco is less harmful than smoking teabacco made from nicotine patches, or smoking traditional tobacco cigarettes. Considering the limited potential health harm of smoking teabacco made from lozenges, and that nicotine lozenges represent the only form of smoking cessation support for individuals entering smoke-free prisons, we caution against the removal of nicotine lozenges from Queensland's prisons, at least until further research directly establishes health harms associated with this form of teabacco.

The presence of carbon nanostructures in bakery products induces metabolic stress in human mesenchymal stem cells through CYP1A and p53 gene expression

Ingredients commonly present in processed foods are excellent substrates for chemical reactions during modern thermal cooking or processing, which could possibly result in deteriorative carbonization changes mediated by a variety of thermal reactions. Spontaneous self-assembling complexation or polymerization of partially combusted lipids, proteins, and other food macromolecules with synthetic food additives during high temperature food processing or baking (200-250 °C) would result in the formation of carbon nanostructures (CNs). These unknown nanostructures may produce adverse physiological effects or potential health risks. The present work aimed to identify and characterize the nanostructures from the crusts of bread. Furthermore, a toxicological risk assessment of these nanostructures was conducted using human mesenchymal stem cells (hMSCs) as a model for cellular uptake and metabolic oxidative stress, with special reference to induced adipogenesis. CNs isolated from bread crusts were characterized using transmission electron microscopy. The in vitro risk assessment of the CNs was carried out in hMSCs using an MTT assay, cell morphological assessment, a reactive oxygen species assay, a mitochondrial trans-membrane potential assay, cell cycle progression assessment and gene expression analysis. Our results revealed that bread crusts contain CNs, which may form during the bread-making process. The in vitro results indicate that carbon nanostructures have moderately toxic effects in the hMSCs at a high dose (400 μg/mL). The mitochondrial trans-membrane potentials and intracellular ROS levels of the hMSCs were altered at this dose. The levels of the mRNA transcripts of metabolic stress-responsive genes such as CAT, GSR, GSTA4, CYP1A and p53 were significantly altered in response to CNs.

Proaporphine and aporphine alkaloids with acetylcholinesterase inhibitory activity from Stephania epigaea

An unusual proaporphine alkaloid bearing an isopropanenitrile group at isoquinoline nitrogen, named epiganine A (1) and a new aporphine alkaloid, epiganine B (2), together with eight known alkaloids, pronuciferine (3), dehydrodicentrine (4), romerine (5), romeline (6), N-methylcalycinine (7), phanostenine (8), dicentrine (9), and N-methyllaurotetanine (10), were isolated from the roots of Stephania epigaea. The absolute configuration of 1 was determined by calculating electronic circular dichroism (ECD) and comparing with experimental data. Compounds 2 and 4 showed strong acetylcholinesterase (AChE) inhibitory effects with the IC50 values of 4.36 and 2.98μM, respectively. Compounds 5-9 also exhibited potent AChE inhibitory activities.