Steviosid aus Süßkraut

The diterpene glycoside stevioside is the most abundant among a group of sweet steviol glycosides, present in sweetleaf (Stevia rebaudiana), which is naturally occurring in Paraguay. It has already been used by the Guarani Indians as a sweetener. Since 2011 such “steviosides” have an EU approval as sweeteners E 960. They taste ca. 250 times sweeter than sucrose. Meanwhile, they have got a significant recognition, not least due to their use in Coca Cola life®. We describe the isolation of stevioside and rebaudioside A from dried leaves of the sweetleaf plant. The complete set of spectra for stevioside is reported. Based on students' laboratory work this project is a follow up of the book “Classics in Spectroscopy” by S. Berger und D. Sicker (Wiley‐VCH 2009).     

γ‐Conicein und Coniin aus Geflecktem Schierling

Socrates is the most famous victim of hemlock poisoning by drinking the cup of hemlock after being condemned to death in Athens in 399 BC. Lethal poisons are γ‐coniceine and coniine, the two most abundant Conium alkaloids which smell like mouse urine. It causes a shudder that the victim is gradually paralyzed under consciousness and that there is no antidote. Poison hemlock is also strongly poisonous to range animals. Therefore, agriculture suppresses hemlock. Coniine was the first alkaloid made synthetically (Ladenburg, 1866). Today, hemlock poisons have no medical use. We describe the isolation of γ‐coniceine and coniine from home‐grown and wild poison hemlock. Their set of spectra is reported and interpreted. Based on students laboratory work and this time on our own preparative commitment as academic supervisors this project is a follow up of the book “Classics in Spectroscopy” by S. Berger und D. Sicker (Wiley‐VCH 2009).     

Bioactive principles in exudate gel from the leaf of Aloe fleurentiniorum,traditionally used as folkloric medicine by local people of Aridah and Fayfa mountains,Saudi Arabia

Aloe fleurentiniorum is a desert plant that is occasionally used to treat wounds by local people of Aridah and Fayfa mountains in Saudi Arabia. However, medicinal value of the plant has not been scientifically established. The purpose of this study was to determine the bioactive phytocomponents contained in the exudate gel (EG) from the leaves of Aloe fleurentiniorum using GC–MS and FT-IR studies, as well as antibacterial assays. Medicinally important bioactive compounds were identified using GC–MS analysis. The bioactive compounds are “pregn-5-ene-3α,20-diol”, “16α-methyl-pregnane-11,20-dione”, “3-hydroxy-(3α,5α)-, ursodeoxycholic acid”, “1-heptatriacotanol”, “allopregnane-7α,11α-diol-3,20-dione”, “D-arabino-hexopyranoside”, “2-octadecenoic acid methyl ester”, “D-ribo-hexose,2,6-dideoxy-3-O-methyl glucosamine”, “N-acetyl-N-benzoyl-alpha-D-glucopyranoside”, “nonyl 1-thio pregnenolone”, “5-cholestene-3-ol, 24-methyl-cholestanol”, and “D-allose hexadecanoic acid methyl ester”. Furthermore, specific groups and their respective chemical compounds were identified via FT-IR spectroscopy studies. The FT-IR spectroscopy of EG showed various functional groups at 3354, 2945, 2832, 2523, 2046, 1707, 1451, 1108, 1031, 880, 737 and 610 cm⁻¹. The FT-IR peaks revealed the likely presence of various compounds such as glycosides, flavonoids, steroids, saponins, flavonoids, amino sugars, cutin and isothiocyanate. Moreover, EG produced a wide range of antibacterial effects on some screened human pathogenic bacteria.     

Shift Reagents in NMR Spectroscopy

The number of possible applications of NMR spectroscopy has rapidly increased during the past few years. New fields of applications have been opened by the development of supraconducting solenoids and various spin-decoupling techniques and by the method of “pulsed Fourier transform NMR-spectroscopy”. These methods originate mainly from progress in instrumentation. Recently, another “technique” has been introduced into NMR spectroscopy, which—principally on the basis of chemical and spectroscopic experience—is much less expensive but nevertheless useful. The basic principles, background, and most important applications of this method, known as the “NMR-shift-reagent technique”, form the subject of this paper.     

Friedelin aus Kork

Cork of the cork oak is a fascinating natural material, used since ancient times. According to a close sight at cork, in 1665 the term “cell” was coined for use in biology. Friedelin, a complex pentacyclic triterpene ketone, is a constituent of cork. The isolation of friedeline is described as well as its history. All analytical spectra were recorded and are reproduced either in the main part or in the supporting information. The NMR‐ and mass‐spectra have been interpreted and compared with theoretical calculations of the ¹³C chemical shifts. The project is a follow up of the recent book “Classics in Spectroscopy” by S. Berger und D. Sicker (Wiley‐VCH 2009).     

Steroidal saponins from the bulbs of Allium karataviense.

Chemical examination of the bulbs of Allium karataviense led to the isolation of five new spirostanol saponins (7-11) and a new furostanol saponin (12), together with a known steroidal sapogenin (1) and five known saponins (2-6). The structures of the new saponins were determined by detailed analysis of their spectral data, including two-dimensional NMR spectroscopy. The steroidal saponins produced by A. karataviense, except for 5 and 6, were found to be based upon (25R)-5 alpha-spirostane-2 alpha,3 beta,5,6 beta-tetrol (alliogenin) and contain a beta-D-glucopyranosyl moiety with the formation of an O-glycoside linkage to C-2 of the polyhydroxylated steroidal skeleton as the common structural feature. The isolated compounds were evaluated for cytostatic activity against human promyelocytic leukemia HL-60 cells.     

Inducing Axial Chirality in a “Geländer” Oligomer by Length Mismatch of the Oligomer Strands

Helical molecules are not only esthetically appealing due to their structural beauty, they also display unique physical properties as a result of their chirality. We describe herein a new approach to “Geländer” oligomers by interlinking two oligomer strands of different length. To compensate for the dimensional mismatch, the longer oligo(benzyl ether) oligomer wraps around the oligophenyl backbone. The new “Geländer” oligomer 1 was assembled in a sequence of functional‐group transformations and cross‐coupling steps followed by final cyclizations based on nucleophilic substitution reactions, and was fully characterized, including X‐ray diffraction analysis. The isolation of pure enantiomers enabled the racemization process to be studied by circular dichroism spectroscopy.     

The regio- and stereochemistry of the alkoxide-induced ring-opening of methoxymethylidene-substituted homopthalic anhydride

Ring-opening of methoxymethylidene-substituted homophthalic anhydride (1) by methoxide occurs by two modes. Attack at the 1-position (“benzoate” carbonyl) leads to a stable acid-ester. A combination of unambiguous syntheses and ¹H- and ¹³C-n.m.r. spectroscopy has been used to show that this material has the “benzoate ester, acrylic acid” structure (5). This corrects the structure assignment given earlier for this material, which incorrectly concluded “benzoic acid, acrylate ester”, (2). Compound (2), resulting from attack at the “acrylate” carbonyl, is a co-product of (5), but is unstable. It recyclises in an alternative fashion to give (dihydro)isocoumarin-type products (15) and (16).     

Scalable ambient synthesis of water‐soluble poly(β‐hydroxythio‐ether)s

Proton transfer polymerization through thiol‐epoxy “click” reaction between commercially available and hydrophilic di‐thiol and di‐epoxide monomers is carried out under ambient conditions to furnish water‐soluble polymers. The hydrophilicity of monomers permitted use of aqueous tetrahydrofuran as the reaction medium. A high polarity of this solvent system in turn allowed for using a mild catalyst such as triethylamine for a successful polymerization process. The overall simplicity of the system translated into a simple mixing of monomers and isolation of the reactive polymers in an effortless manner and on any scale required. The structure of the resulting polymers and the extent of di‐sulfide defects are studied with the help of 13C‐ and ¹H‐NMR spectroscopy. Finally, reactivity of the synthesized polymers is examined through post‐polymerization modification reaction at the backbone sulfur atoms through oxidation reaction. The practicality, modularity, further functionalizability, and water solubility aspects of the described family of new poly(β‐hydroxythio‐ether)s is anticipated to accelerate investigations into their potential utility in bio‐relevant applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3381–3386     

Analysis of a new drug of abuse: Cathinone derivative 1‐(3,4‐dimethoxyphenyl)‐2‐(ethylamino)pentan‐1‐one

Recently, novel psychoactive drugs for human abuse such as amphetamines, phenethylamines, benzofuries, and tryptamines, cathinones have gained high popularity. These designer drugs are mainly sold via online stores as “bath salts” and are labeled “not for human consumption.” Due to the novelty of the compounds, only a little information about pharmacology, toxicology, and the long‐term damage they may cause is available. Moreover, there are only few analytical methods for their identification and analysis. Among new cathinone derivatives, 1‐(3,4‐dimethoxyphenyl)‐2‐(ethylamino)pentan‐1‐one (DL‐4662), became available via an internet shop. A sample of this compound was purchased and investigated. The first aim of our study was an identity check by NMR spectroscopy and gas chromatography with mass spectrometry. As many of the recreational drugs are chiral and are mainly sold as racemates, a further goal of our research was enantioseparation by gas chromatography with mass spectrometry and high‐performance liquid chromatography with UV detection, to prove whether DL‐4662 was traded enantiomerically pure or as racemic mixture. Both chiral separation methods showed the presence of a racemate.     

Transmutation Theory in the Greek Alchemical Corpus

This paper studies transmutation theory as found in the texts attributed to Zosimus of Panopolis, “the philosopher Synesius,” and “the philosopher Olympiodorus of Alexandria.” It shows that transmutation theory (i.e. a theory explaining the complete transformation of substances) is mostly absent from the work attributed to these three authors. The text attributed to Synesius describes a gilding process, which is similar to those described by Pliny and Vitruvius. The commentary attributed to Olympiodorus is the only text studied here that describes something similar to a transmutation theory. It is unclear, however, if this was a theory of transmutation or if the writer meant something more like the literal meaning of the word “ekstrophē,” a term used to describe the transformation of metals, as the “turning inside-out” of what is hidden in a substance. A similar conception of ekstrophē can be found in the works of Zosimus, who discussed transmutation to make an analogy with self-purification processes, which, from the perspective of his own anthropogony, consisted in the “turning inside-out” of the “inner human” (esō anthrōpos).     

Do Anti‐Bredt Natural Products Exist? Olefin Strain Energy as a Predictor of Isolability

Bredt’s rule holds a special place in the realm of physical organic chemistry, but its application to natural products chemistry—the field in which the rule was originally formulated—is not well defined. Herein, the use of olefin strain (OS) energy as a readily calculated predictor of the stability of natural products containing a bridgehead alkene is introduced. Schleyer first used OS energies to classify parent bridgehead alkenes into “isolable”, “observable”, and “unstable” classes. OS calculations on natural products, using contemporary forcefield methods, unequivocally predict all structurally verified bridgehead alkene natural products to be “isolable”. Thus, when one assigns the structure of a putative bridgehead alkene natural product, an OS in the “observable” or “unstable” ranges is a red flag for error.     

Target Directed Drug Synthesis: The Aminoacyl-tRNA Synthetases as Possible Targets

The “tailor-made” pharmaceutical has been an old dream ever since Paracelsus' days. His saying “Dosis sola facit venenum” is still valid. The ideal pharmacon should inhibit the pathological process or the parasitical organism to a maximum while causing as little harm as possible to the human organism. In order to achieve this goal one must try to make use of metabolic differences between the metabolism of the pathological organism and normal human metabolism in a rational way. With today's improved knowledge of enzymatic processes this seems to be a possible and highly promising approach. The pharmaceutical should act upon a process of central importance, such as the process of protein biosynthesis, where the required highly accurate construction of the macromolecules is achieved by a “proofreading” process. It is shown that this “proofreading” mechanism exhibits specific difference in different species.     

Cation exchange media provide a multi-stage,orthogonal catch and release method for MIDA boronates bearing basic centers

An operationally simple and rapid purification of MIDA boronates is described. This method allows separation of MIDA boronates containing basic centers from those that are neutral as well as separation from species that do not contain the MIDA moiety using a single “catch and release” purification medium. Application of this method to the purification of reductive amination products is described. It is hoped that this facile, rapid and conceptually new isolation will stimulate further investigation of other functionalized silica gel media for the isolation of MIDA boronate building blocks.     

No‐Barrier Theory: Calculating Rates of Chemical Reactions from Equilibrium Constants and Distortion Energies

No‐barrier theory is a new approach to the calculation of rate constants for reactions in solution, from the corresponding equilibrium constants. It requires relatively small molecular orbital theory calculations, and has been very successful. It is in the spirit of Marcus theory, but does not require an “intrinsic barrier”. The approach is explained, with an examination of the way in which the ideas on which it is based were “in the air”.     

Spectral interferences in inductively coupled plasma atomic emission spectrometry-I: A theoretical and experimental study of the effect of spectral bandwidth on selectivity,limits of determination,limits of detection and detection power

This article links up with recent work on high resolution spectroscopy in this laboratory [1] and primarily deals with the effect of the spectral resolution on the “selectivity” in the case of samples that emit line-rich spectra. The concept of selectivity, as developed by KAISER [8] on the basis of the set of calibration equations for a multicomponent system, is considered as a useful starting-point but is rejected as a meaningful analytical figure of merit. Instead the concept of “line selectivity” is introduced as a criterion and related to the analytical error. This approach leads to a definition of the limit of determination such that its dependence on the spectral resolution can be clearly and unambiguously revealed in any concrete situation, that is, once the sample type has been specified. Such a specification is necessary since the numerical values of quantities related to selectivity are inherently linked with sample composition.Thus the theory is illustrated with practical examples including the results of a multiplicity of simulated line overlap situations using representative experimental line profiles measured at two extreme levels of resolution, referred to as “medium” and “high” resolution.It is shown that in the case of line overlap the limit of determination may exceed the limit of detection by one or even two orders of magnitude, unless line selection is based on a selectivity criterion so that the limit of detection is inherently coupled to the limit of determination. It is also shown that the prime benefit of high resolution spectroscopy is the reduction of the limit of determination, not that of the limit of detection. This benefit is found only if the spectral resolution can improve the selectivity, thus if there exist situations of line overlap.     

Coverage‐Dependent Variation of Adsorption Configurations of Methionine on Ge(100)

The adsorption configurations of methionine molecules on the Ge(100) surface have been studied by using DFT calculations, core‐level photoemission spectroscopy (CLPES), and low‐energy electron diffraction (LEED) to scrutinize the adsorption structure as a function of coverage. At first, we obtained two important and stable structures. One is the most stable structure between these structures described as an “O H dissociated‐N dative‐S dative‐bonded structure” and the other is a less stable adsorption structure of these indicating an “O H dissociated‐S dative‐bonded structure” by using DFT calculations. We also performed CLPES to clarify our DFT calculation results. Through the spectral analysis of the S 2p, C 1s, N 1s, and O 1s core‐level spectra, we acquired the reasonable results that also revealed quite different bonding configurations depending on the methionine coverage. At low coverage (ca. 0.30 ML), a single type of sulfur and charged nitrogen peaks, which indicate an “O H dissociated‐N dative‐S dative‐bonded structure”, were observed. On the other hand, two types of sulfur peaks with thiol formation and two nitrogen peaks with neutralized and charged characteristics were monitored at a higher coverage (0.60 ML and above), which can be described as an “O H dissociated‐S dative‐bonded structure”. Hence, we can clearly demonstrate that our results obtained from CLPES spectra and DFT calculations are matched well with each other. Moreover, we additionally confirmed that the relative population of the two types of thiols and amines being included in methionine in between half monolayer induces a surface reorientation in the ordering from 2×1 to 1×1 employing LEED. This interesting variation of the methionine adsorbed on the Ge(100) surface by coverage dependence will be precisely discussed by using DFT calculations, CLPES, and LEED.     

From your eyes only: Efficiency of nuclear and mitochondrial DNA isolation from contact lenses at crime scenes

Recovering appropriate evidence from crime scenes to identify the perpetrator, or in certain cases, the victim, is one of the main goals of forensic investigation. The current practice includes collection of objects from which “trace” or “touch” DNA may be retrieved. Contact lenses, worn by the perpetrator/victim, represent a potentially good source of DNA. This is based on their exposure to touch DNA and the release and regeneration of epithelial cells from the eye. This study takes these premises into account with the objective of analyzing the efficiency of human nuclear and mitochondrial DNA isolation from contact lenses. DNA was collected using a non-destructive technique (double-swab) and subsequently isolated using a silica-based methodology. Although DNA quantification was variable among subjects and contact lenses, it was sufficient to amplify some STRs and successfully sequence mtDNA. The findings from this research provide a proof-of-concept that it is possible to recover, isolate, amplify human nuclear DNA, and characterize mitochondrial DNA from contact lenses left at crime scenes. These results show the potential importance of recovering unusual items from crime scenes as a potential source of DNA to identify the victim and/or suspect.