A Huge PVDF Adsorption Difference Between Resveratrol and ε-Viniferin Allows to Quantitatively Purify Them and to Assess Their Anti-Tyrosinase Property

Repeated chromatographic analyses of polyphenolic vine stalks extracts allowed us to note a huge adsorption difference on polyvinylidene fluoride (PVDF), between trans-resveratrol 1 and (+)-trans-ε-viniferin 2. We could optimize the conditions (solvent, saturation of the process), for this polymer to adsorb very selectively 2, with regard to the monomer 1 that remains in solution. Since membrane filters made of PVDF are quite often used for HPLC samples filtration, this observation prompted us to inform phytochemists studying plant stilbenoid contents. Based on this background information, we developed a straightforward and inexpensive enrichment process for either 1 and/or 2, from crude Vitis vinifera stalks extracts, allowing to get them in a pure form. Having at hand large amounts of these two pure compounds, they were tested and compared to a set of other relevant molecules for some biological properties: trans-ε-viniferin 2 was shown to be the most powerful tyrosinase inhibitor, among all samples tested.     

A Facile Synthesis of an Advanced Glycosylation Endproduct 2-(2′-furoyl)-4(5)-(2′-furanyl)-1H-imidazole

Abstract: A three step synthesis of the advanced glycosylation endproduct 2-(2′-furoyl)-4(5)-(2′-furanyl)-1H-imidazole (4, FFI) has been achieved from 2-acetylfuran. The key step in the synthesis was the rearrangement of the hydrazinium bromide 3 in refluxing methanol.     

STUDY OF THE ADSORPTION OF HUMAN SERUM ALBUMIN ON REVERSED-PHASE SUPPORTS.

This work examines the adsorption of Human Serum Albumin (HSA) on a Reversed-Phase High Performance Liquid Chromatographic (RPLC) support. The adsorption experiments were performed by frontal analysis. Adsorption isotherms were determined in pure buffer and in the presence of acetonitrile. Saturation is always reached, even at the lower protein concentrations. In view of the pore size of the particles (80 Å), it is assumed that HSA is adsorbed on the external surface of silica

In presence of acetonitrile, a variability in the amount of HSA adsorbed is found showing a maximum at 25% of acetonitrile. Slower adsorption kinetics are observed when the concentration of the organic modifier in the eluent is increased. The reversibility of HSA binding to the surface was investigated by desorbing the protein with 40% acetonitrile. The amount of HSA irreversibly adsorbed depends upon the experimental conditions used during the adsorption step. It is at a maximum when HSA is adsorbed with 25% acetonitrile. As the temperature is raised and only in the presence of acetonitrile, an important increase of the amount of HSA irreversibly adsorbed is observed.     

Targeting Human C‐Type Lectin‐like Molecule‐1 (CLL1) with a Bispecific Antibody for Immunotherapy of Acute Myeloid Leukemia

Acute myeloid leukemia (AML), which is the most common acute adult leukemia and the second most common pediatric leukemia, still has a poor prognosis. Human C‐type lectin‐like molecule‐1 (CLL1) is a recently identified myeloid lineage restricted cell surface marker, which is overexpressed in over 90 % of AML patient myeloid blasts and in leukemic stem cells. Here, we describe the synthesis of a novel bispecific antibody, αCLL1‐αCD3, using the genetically encoded unnatural amino acid, p‐acetylphenylalanine. The resulting αCLL1‐αCD3 recruits cytotoxic T cells to CLL1 positive cells, and demonstrates potent and selective cytotoxicity against several human AML cell lines and primary AML patient derived cells in vitro. Moreover, αCLL1‐αCD3 treatment completely eliminates established tumors in an U937 AML cell line xenograft model. These results validate the clinical potential of CLL1 as an AML‐specific antigen for the generation of a novel immunotherapeutic for AML.     

Data-handling strategies for metabonomic studies: example of the UHPLC-ESI/ToF urinary signature of tetrahydrocannabinol in humans

Metabonomics has become a very valuable tool and many research fields rely on results coming out from this combination of analytical techniques, chemometric strategies, and biological interpretation. Moreover, the matrices are more and more complex and the implications of the results are often of major importance. In this context, the need for pertinent validation strategies comes naturally. The choice of the appropriate chemometric method remains nevertheless a difficult task due to particularities such as: the number of measured variables, the complexity of the matrix and the purposes of the study. Consequently, this paper presents a detailed metabonomic study on human urine with a special emphasis on the importance of assessing the data's quality. It also describes, step by step, the statistical tools currently used and offers a critical view on some of their limits. In this work, 29 urine samples among which 15 samples obtained from tetrahydrocannabinol (delta-9-tetrahydrocannabinol)-consuming athletes, 5 samples provided by volunteers, and 9 samples obtained from athletes were submitted to untargeted analysis by means of ultra high-pressure liquid chromatography–electrospray ionization–time-of-flight mass spectrometry. Next, the quality of the obtained data was assessed and the results were compared to those found in databases. Then, unsupervised (principal component analysis (PCA)) and supervised (ANOVA/PCA, partial least-square–discriminant analysis (PLS-DA), orthogonal PLS-DA) univariate and multivariate statistical methods were applied.

New advances in countercurrent chromatography and centrifugal partition chromatography: focus on coupling strategy

Countercurrent chromatography (CCC) is an attractive separation method because the analytes are partitioned between two immiscible liquid phases avoiding problems related to solid stationary phase. In recent years, this technique has made great progress in separation power and detection potential. This review describes coupling strategies involving high speed CCC (HSCCC) or centrifugal partition chromatography (CPC). It includes on-line extraction–isolation, hyphenation with mass spectrometry (MS) and nuclear magnetic resonance (NMR) detectors, multidimensional CCC (MDCCC), two-dimensional CCC (2D-CCC), on-line coupling with liquid chromatography (LC), and biological tests, and innovative off-line developments. The basic principles of each method are presented and applications are summarized.     

Carbon nanotube poroshell silica as a novel stationary phase for fast HPLC analysis of monoclonal antibodies

A new carbon nanotube porous silica poroshell stationary phase was developed. The chromatographic support was coated with ultrashort single-wall carbon nanotubes (SWCNTs) in a noncovalent way. It was demonstrated that the porous amino silica surface of the 300 NH₂ poroshell column stabilized with 1-methyl-2-pyrrolidinone efficiently and stably adsorbed SWCNTs onto the chromatographic support. It was shown that this novel poroshell carbon nanotube (CNT) stationary phase was very useful for the HPLC separation of a series of monoclonal antibodies (mAbs) in a short analysis time (<3 min). The high-performance liquid chromatography (HPLC) method was validated and was successfully tested for the fast quantitative and qualitative control of chemotherapeutic bags fabricated in a hospital pharmacy.     

Introducing enzyme selectivity: a quantitative parameter to describe enzymatic protein hydrolysis

Enzyme selectivity is introduced as a quantitative parameter to describe the rate at which individual cleavage sites in a protein substrate are hydrolyzed relative to other cleavage sites. Whey protein isolate was hydrolyzed by Bacillus licheniformis protease, which is highly specific for Glu and Asp residues. The molar concentration of all peptides (58) from β-lactoglobulin formed during hydrolysis was determined from the UV₂₁₄ signal. The quality of identification and quantification of the peptides were described by newly defined parameters: the peptide sequence coverage (on average 94 %) and the molar sequence coverage (on average 75 %). The selectivity was calculated from the rate of hydrolysis of each cleavage site, and showed differences of up to a factor of 5,000. The ability to quantitatively discriminate the enzyme preference towards individual cleavage sites is considered essential to the understanding of enzymatic protein hydrolysis.      

Gold Nanorods with Phase‐Changing Polymer Corona for Remotely Near‐Infrared‐Triggered Drug Release

Herein, we report a new drug‐delivery system (DDS) that is comprised of a near‐infrared (NIR)‐light‐sensitive gold‐nanorod (GNR) core and a phase‐changing poly(ε‐caprolactone)‐b‐poly(ethylene glycol) polymer corona (GNR@PCL‐b‐PEG). The underlying mechanism of the drug‐loading and triggered‐release behaviors involves the entrapment of drug payloads among the PCL crystallites and a heat‐induced phase change, respectively. A low premature release of the pre‐loaded doxorubicin was observed in PBS buffer (pH 7.4) at 37 °C (<10 % of the entire payload after 48 h). However, release could be activated within 30 min by conventional heating at 50 °C, above the T_m of the crystalline PCL domain (43.5 °C), with about 60 % release over the subsequent 42 h at 37 °C. The NIR‐induced heating of an aqueous suspension of GNR@PCL‐b‐PEG under NIR irradiation (802 nm) was investigated in terms of the irradiation period, power, and concentration‐dependent heating behavior, as well as the NIR‐induced shape‐transformation of the GNR cores. Remotely NIR‐triggered release was also explored upon NIR irradiation for 30 min and about 70 % release was achieved in the following 42 h at 37 °C, with a mild warming (<4 °C) of the surroundings. The cytotoxicity of GNR@PCL‐b‐PEG against the mouse fibroblastic‐like L929 cell‐line was assessed by MTS assay and good compatibility was confirmed with a cell viability of over 90 % after incubation for 72 h. The cellular uptake of GNR@PCL‐b‐PEG by melanoma MEL‐5 cells was also confirmed, with an averaged uptake of 1250(±110) particles cell^?1 after incubation for 12 h (50 μg mL^?1). This GNR@PCL‐b‐PEG DDS is aimed at addressing the different requirements for therapeutic treatments and is envisaged to provide new insights into DDS targeting for remotely triggered release by NIR activation.     

Synergy,Compatibility, and Innovation: Merging Lewis Acids with Stereoselective Enamine Catalysis

In recent years there has been an accelerated rate of development in the field of organocatalysis, with asymmetric organocatalysis now reaching full maturity. The invention of new organocatalytic reactions and the exploration of new concepts now appear in tandem with the application of organocatalytic techniques in the synthesis of natural products and active pharmaceutical ingredients (APIs). After a “golden rush” in organocatalysis, researchers are now starting to combine different methods, thereby taking advantage of the significant benefits of synergy. Metals are used in combination with organocatalytic processes, thus reaching complexity that is found in nature, where enzymes take advantage of the presence of certain metals to increase the arsenal of organic transformations available. In this Focus review, we illustrate the possibility of a “happy marriage” between Lewis acids and organocatalytic stereoselective processes. Questions have been raised about the combination of Lewis acids and organocatalysis owing to the presence of water and/or strong bases in these processes. Some Lewis acids have been shown to be compatible with organocatalysis and concepts relating to their use will be illustrated herein. To summarize the fruitful use of Lewis acids in stereoselective organocatalytic processes, we will draw attention to the advantages and selectivity achieved using this method.