Elucidation of the Concise Biosynthetic Pathway of the Communesin Indole Alkaloids

The communesins are a prominent class of indole alkaloids isolated from Penicillium species. Owing to their daunting structural framework and potential as pharmaceuticals, communesins have inspired numerous synthetic studies. However, the genetic and biochemical basis of communesin biosynthesis has remained unexplored. Herein, we report the identification and characterization of the communesin (cns) biosynthetic gene cluster from Penicillium expansum. We confirmed that communesin is biosynthesized by the coupling of tryptamine and aurantioclavine, two building blocks derived from L ‐tryptophan. The postmodification steps were mapped by targeted‐gene‐deletion experiments and the structural elucidation of intermediates and new analogues. Our studies set the stage for the biochemical characterization of communesin biosynthesis. This knowledge will aid our understanding of how nature generates remarkable structural complexity from simple precursors.     

Flow of pulp fibre suspension and slurries: A review

This paper reviews recent experimental and modeling work on biomass multiphase flow of suspensions and slurries. Problems associated with fibre flows (e.g., fibre flocculation, velocity profiles, flow regimes) have received considerable attention for these processes, involving both liquid–solid and gas–liquid–solid systems. Advanced experimental techniques have been employed in efforts to understand the flows. However, each of these experimental techniques is somewhat limited in its application. In the modelling work, mechanistic models, including those based on CFD, are being developed, but turbulence and interactions among particles and between the particles and fluid have so far limited the success of such models. Future work is needed to improve biomass energy and materials conversion processes.     

Die Darstellung von o-Nitrososalicyls?ure und ihre Verwendung zur Bestimmung des Nickels

Zusammenfassung o-Nitrososalicylsäure kann leicht und ohne große Kosten hergestellt werden. Das Reagens gibt mit Nickel-Ionen ein rotes, in Wasser lösliches innerkomplexes Salz. Auf Grund dieser Reaktion kann Nickel-Ion einfach und empfindlich bestimmt werden. Da die meisten anderen Metalle mit dem Reagens gefärbte Salze wechselnder Löslichkeit geben, ist es wünschenswert, die vorstehende experimentelle Arbeit fortzusetzen.Gewidmet aus Anlaß des 100jährigen Bestehens des Laboratoriums Fresenius.Diese Arbeit übersandte Dr. Oskar Baudisch, Research Director of the New York State Research Institute of the Saratoga Springs Commission, Saratoga Springs, New York.     

Evaluation of High-Performance Thin-Layer Chromatography for the Quantification of Phenylpropanoids in Commercial Echinacea Products

JPC – Journal of Planar Chromatography – Modern TLC - There is a large chemical variability between commercially available Echinacea for both research and consumption impacts on the...     

Square Wave Electroanalysis at Generator–Collector Gold–Gold Double Hemisphere Junctions

Gold–gold double‐hemisphere junction electrodes with an inter‐electrode gap of typically 1 µm are employed for generator–collector square wave voltammetry. Electrochemical data are recorded as a function of both generator and collector potential to give three‐dimensional response “maps”. At sufficiently low frequencies, close‐to‐steady‐state conditions for the collector response are achieved and peak responses complementary to those for the generator electrode are recorded. Due to localised interelectrode gap diffusion (fast) as opposed to peripheral diffusion (slow), information about reaction products and intermediates can be obtained. Local pH gradient effects provide additional “fingerprint” information beneficial for future application in analytical detection.     

Structural evolution of a two-component organogel

Dry reverse micelles of AOT in isooctane spontaneously undergo a microstructural transition to an organogel upon the addition of a phenolic dopant, p-chlorophenol. This microstructural evolution has been studied through a combination of light scattering, small-angle neutron scattering (SANS), NMR, and rheology. Several equilibrium stages between the system of dry reverse micelles of AOT and a 1:1 AOT/p-chlorophenol (molar ratio) gel in isooctane have been examined. To achieve this, p-chlorophenol is added progressively to the dilute solutions of AOT in isooctane, and this concentration series is then analyzed. The dry micelles of AOT in isooctane do not undergo any detectable structural change up to a certain p-chlorophenol concentration. Upon a very small increment in the concentration of p-chlorophenol beyond this "threshold" concentration, large strandlike aggregates are observed which then evolve to the three-dimensional gel network.     

Solvent-free simulations of fluid membrane bilayers

A molecular level model for lipid bilayers is presented. Lipids are represented by rigid, asymmetric, soft spherocylinders in implicit solvent. A simple three parameter potential between pairs of lipids gives rise to a rich assortment of phases including (but not limited to) micelles, fluid bilayers, and gel-like bilayers. Monte Carlo simulations have been carried out to verify self-assembly, characterize the phases corresponding to different potential parametrizations, and to quantify the physical properties associated with those parameter sets corresponding to fluid bilayer behavior. The studied fluid bilayers have compressibility moduli in agreement with experimental systems, but display bending moduli at least three times larger than typical biological membranes without cholesterol.     

Lattice effects on the spin-crossover profile of a mononuclear manganese(III) cation

Six solvated salts of a mononuclear manganese(III) complex with a chelating hexadentate Schiff base ligand are reported. One member of the series, [MnL]PF(6)?0.5?CH(3)OH (1), shows a rare low-spin (LS) electronic configuration between 10-300?K. The remaining five salts, [MnL]NO(3)?C(2)H(5)OH(2), [MnL]BF(4)?C(2)H(5)OH(3), [MnL]CF(3)SO(3)?C(2)H(5)OH (4), [MnL]ClO(4)?C(2)H(5)OH (5) and [MnL]ClO(4)?0.5?CH(3)CN (6), all show gradual incomplete spin-crossover (SCO) behaviour. The structures of all were determined at 100?K, and also at 293?K in the case of 3-6. The LS salt [MnL]PF(6)?0.5?CH(3)OH is the only member of the series that does not exhibit strong hydrogen bonding. At 100?K two of the four SCO complexes (2 and 4) assemble into 1D hydrogen-bonded chains, which weaken or rupture on warming. The remaining SCO complexes 3, 5 and 6 do not form 1D hydrogen-bonded chains, but instead exhibit discrete hydrogen bonding between cation/counterion, cation/solvent or counterion/solvent and show no significant change on warming.     

Microwave‐Assisted Cross‐Coupling for the Construction of Diaryl Sulfides

The construction of diaryl sulfides through the cross‐coupling of aryl iodides and thiols in microwave heating is described. By using this method, a variety of diaryl sulfides can be prepared in a mild condition and in high yields. Deactivated 4‐nitrothiophenol was effective to afford the product in 94% yield. Sterically hindered ortho‐substituted aryl iodides or thiophenols provided diaryl sulfides effectively by this microwave‐assisted coupling reaction.     

Electrospray ionization mass spectrometry for analysis of low-molecular-weight anticancer drugs and their analogues

In this study, several anticancer drugs and their analogues consisting of organic and organometallic compounds were analyzed by electrospray ionization mass spectrometry (ESI/MS) using a quadrupole mass spectrometer. Protonated molecular ions [M+H]⁺ were observed for all of the compounds studied, and in the case of the two steroid sulfates, deprotonated molecular ions [M-H]^? were obtained. Tandem mass spectrometry was performed on these quasimolecular ions, and the product ions formed provided useful fragmentation patterns that were characteristic for the compounds. This study provides evidence that ESI/MS is a sensitive technique for structure confirmation and identification of small organic and organometallic molecules.