Histone deacetylase inhibitors as a tool to up-regulate new fungal biosynthetic products: isolation of EGM-556, a cyclodepsipeptide, from Microascus sp

The histone deacetylase (HDAC) inhibitor suberoylanilide hydroxamic acid (SAHA) was used to turn on the biosynthesis of EGM-556, a new cyclodepsipeptide of hybrid biosynthetic origin, isolated from the Floridian marine sediment-derived fungus Microascus sp. The absolute configurations of three chiral centers were determined by Marfey's derivatization. EGM-556 represents one of the few examples in which silent biosynthetic genes, encoding a new secondary metabolite, were activated by means of epigenetic manipulation of the fungal metabolome.     

Molecular mechanics (MM3) parameterization of hydroxylamine and methyl derivatives

Based on results of electron diffraction, gas phase infrared spectroscopy (IR), and MP2/6-31 + G* ab initio calculations, a set of molecular mechanics (MM3) parameters was developed for molecules containing the N(sp³)—O(sp³) moiety. Using this set of parameters, MM3 is able to reproduce structures (bond lengths and bond angles) and vibrational spectra satisfactorily. © 1994 by John Wiley & Sons, Inc.     

Polydopamine‐Mediated Immobilization of Alginate Lyase to Prevent P. aeruginosa Adhesion

Given alginate's contribution to Pseudomonas aeruginosa virulence, it has long been considered a promising target for interventional therapies, which have been performed by using the enzyme alginate lyase. In this work, instead of treating pre‐established mucoid biofilms, alginate lyase is immobilized onto a surface as a preventive measure against P. aeruginosa adhesion. A polydopamine dip‐coating strategy is employed for functionalization of polycarbonate surfaces. Enzyme immobilization is confirmed by surface characterization. Surfaces functionalized with alginate lyase exhibit anti‐adhesive properties, inhibiting the attachment of the mucoid strain. Moreover, surfaces modified with this enzyme also inhibit the adhesion of the tested non‐mucoid strain. Unexpectedly, treatment with heat‐inactivated enzyme also inhibits the attachment of mucoid and non‐mucoid P. aeruginosa strains. These findings suggest that the antibacterial performance of alginate lyase functional coatings is catalysis‐independent, highlighting the importance of further studies to better understand its mechanism of action against P. aeruginosa strains.

     

Non-fouling microfluidic chip produced by radio frequency tetraglyme plasma deposition

This Technical Note presents the direct surface modification of a glass/PTFE hybrid microfluidic chip, via radio frequency glow discharge plasma polymerisation of tetraethlylene glycol dimethylether (tetraglyme), to produce hydrophilic, non-fouling, PEO-like surfaces. We use several techniques including X-ray photoelectron spectroscopy (XPS), direct enzyme-linked immunosorbent assays (ELISA) and immunofluorescent imaging to investigate the channel coatings. Our results indicate the successful deposition of a PEO-like coating onto microchannel surfaces that has both solution and shelf stability (>3 months) and is capable of preventing fibrinogen adsorption to the microchannel surfaces.     

Analysis of substances to be used as internal standards in MEKC

The use of internal standards (ISs) improves the quantitative performance of CE. However, ISs chosen for use in CZE often cannot be used for micellar EKC (MEKC). Therefore 22 substances were investigated as potential ISs in MEKC. These substances were selected based upon a literature search. The substances were investigated using a method similar to the standard operating conditions for MEKC as recommended by S. Terabe. Furthermore, the migration time and the corrected migration time (k(S)) were determined for each substance to establish the migration position relative to other peaks in the electropherograms. A combination of eight substances, selected according to the obtained results (t(m) = 4 up to 12 min), was tested for practical benefit and applicability. The peak area precision was in the range of 0.8 and 1.2% (n = 60), and the peaks were well shaped for all the investigated substances. The selected substances covered a wide migration time window and therefore they can be regarded as suitable for future analysis at any required migration position.     

Use of a small particle solid‐core packing for improved efficiency and rapid measurement of sirolimus and everolimus by LC‐MS/MS

Measurement of whole blood sirolimus and everolimus is required in order to optimize patient treatment following solid organ transplant. Assay by LC‐MS/MS is increasingly preferred; however efficient use of the instrument and short turnaround times are crucial. Use of a 1.6 µm solid‐core packing HPLC column (Cortecs) gave significant increases in efficiency, sensitivity and throughput compared with an existing method, following simple protein precipitation of small‐volume (20 μL) whole blood samples. Sirolimus, everolimus and the stable isotopic internal standard (¹³C₂D₄ – everolimus) eluted at around 0.8 min, and total analytical run time was 2.2 min, saving almost 4 min per sample compared with an existing method. Within‐assay imprecision (CV) was 3.3–8.5%, and between‐assay imprecision was 2.2–10.8%. Retrospective assay of external quality assurance samples and comparison of patient samples assayed in parallel showed only small differences (between +6.8 and ?1.9%) in results using the Cortecs column when compared with the existing method. No significant interferences or ion suppression were observed. Copyright © 2015 John Wiley & Sons, Ltd.     

Analysis and deconvolution of dimethylnaphthalene isomers using gas chromatography vacuum ultraviolet spectroscopy and theoretical computations

An issue with most gas chromatographic detectors is their inability to deconvolve coeluting isomers. Dimethylnaphthalenes are a class of compounds that can be particularly difficult to speciate by gas chromatography – mass spectrometry analysis, because of their significant coelution and similar mass spectra. As an alternative, a vacuum ultraviolet spectroscopic detector paired with gas chromatography was used to study the systematic deconvolution of mixtures of coeluting isomers of dimethylnaphthalenes. Various ratio combinations of 75:25; 50:50; 25:75; 20:80; 10:90; 5:95; and 1:99 were prepared to test the accuracy, precision, and sensitivity of the detector for distinguishing overlapping isomers that had distinct, but very similar absorption spectra. It was found that, under reasonable injection conditions, all of the pairwise overlapping isomers tested could be deconvoluted up to nearly two orders of magnitude (up to 99:1) in relative abundance. These experimental deconvolution values were in agreement with theoretical covariance calculations performed for two of the dimethylnaphthalene isomers. Covariance calculations estimated high picogram detection limits for a minor isomer coeluting with low to mid-nanogram quantity of a more abundant isomer. Further characterization of the analytes was performed using density functional theory computations to compare theory with experimental measurements. Additionally, gas chromatography – vacuum ultraviolet spectroscopy was shown to be able to speciate dimethylnaphthalenes in jet and diesel fuel samples.     

A new 3-alkylpyridine alkaloid from the marine sponge Haliclona sp. and its cytotoxic activity

A new alkaloid, 3-dodecyl pyridine containing a terminal cyano group (1), was isolated from the methanol extract of an Indonesia marine sponge Haliclona sp. Its chemical structure was determined by a combination of spectroscopic methods, including 1D and 2D NMR. Bioassay results indicated that compound 1 had moderate cytotoxity against tumour cell lines A549, MCF-7 and Hela with IC₅₀ values of 41.8, 48.4 and 33.2 μM, respectively.