Simultaneous quantification of terpenelactones and flavonol aglycones in hydrolyzed ginkgo biloba extract by liquid chromatography with inline ultraviolet and evaporative light scattering detection

We report here a liquid chromatography (LC) method with inline ultraviolet/evaporative light scattering (UV/ELS) detection for the simultaneous quantification of the terpenelactones and flavonol aglycones in a single sample of hydrolyzed Ginkgo biloba extract (GBE). The sample is hydrolyzed by a rapid and convenient oven heating method for 1 h at 90 degrees C with 10% hydrochloric acid. The 1 h hydrolysis was found to be equivalent to the 2.25 h reflux treatment for dry powder extract, where total flavonol glycosides were 28.4 and 28.1%, respectively. Acceptable precision was achieved for total terpenelactones [relative standard deviation (RSD) = 4.8%] by ELS detection, and total flavonol aglycones (RSD = 2.3%) by UV detection. The analytical range was 1.5 to 7.3% (w/w) for the individual terpenelactones (ELS) and 2.5 to 15.0% (w/w) for the individual glycosides (UV) calculated from the aglycones quercetin, kaempferol, and isorhamnetin. This improved method allows for the first time high throughput sample preparation coupled with the quantification of the predominant compounds generally used for quality control of GBE in a single assay.     

Conversion of N-aromatic amides to O-aromatic esters

[reaction: see text] N-Aromatic secondary amides can be transformed into O-aromatic esters in high yield via N-nitrosamide intermediates. The amides can be generated in situ from the corresponding aromatic amines or nitro compounds, and phenols can easily be made from the esters. The reaction can be modified by addition of methyl methacrylate or toluene at 0 degrees C to give polymerization or deamination, respectively. The rearrangement mechanism may involve radical formation and recombination.     

Design of a calcium-binding protein with desired structure in a cell adhesion molecule

Ca2+, "a signal of life and death", controls numerous cellular processes through interactions with proteins. An effective approach to understanding the role of Ca2+ is the design of a Ca2+-binding protein with predicted structural and functional properties. To design de novo Ca2+-binding sites in proteins is challenging due to the high coordination numbers and the incorporation of charged ligand residues, in addition to Ca2+-induced conformational change. Here, we demonstrate the successful design of a Ca2+-binding site in the non-Ca2+-binding cell adhesion protein CD2. This designed protein, Ca.CD2, exhibits selectivity for Ca2+ versus other di- and monovalent cations. In addition, La3+ (Kd 5.0 microM) and Tb3+ (Kd 6.6 microM) bind to the designed protein somewhat more tightly than does Ca2+ (Kd 1.4 mM). More interestingly, Ca.CD2 retains the native ability to associate with the natural target molecule. The solution structure reveals that Ca.CD2 binds Ca2+ at the intended site with the designed arrangement, which validates our general strategy for designing de novo Ca2+-binding proteins. The structural information also provides a close view of structural determinants that are necessary for a functional protein to accommodate the metal-binding site. This first success in designing Ca2+-binding proteins with desired structural and functional properties opens a new avenue in unveiling key determinants to Ca2+ binding, the mechanism of Ca2+ signaling, and Ca2+-dependent cell adhesion, while avoiding the complexities of the global conformational changes and cooperativity in natural Ca2+-binding proteins. It also represents a major achievement toward designing functional proteins controlled by Ca2+ binding.     

Live biotherapeutic products: the importance of a defined regulatory framework

Probiotics have been defined as “Live microorganisms that when administered in adequate amounts confer a health benefit on the host”. This definition covers a wide range of applications, target populations and (combinations of) microorganisms. Improved knowledge on the importance of the microbiota in terms of health and disease has further diversified the potential scope of a probiotic intervention, whether intended to reach the market as a food, a food supplement or a drug, depending on the intended use. However, the increased interest in the clinical application of probiotics may require specific attention given their administration in a diseased population. In addition to safety, the impact of the type of product, in terms of quality, production method and, e.g., the acceptance of side effects, is now part of the current regulatory constraints for developers. In the European Union, foods are regulated by the European Food Safety Authority and drugs by the European Medicines Agency; in the United States, the Food and Drug Administration (FDA) deals with both categories. More recently, the FDA has defined a new “live biotherapeutic products” (LBP) category, clarifying pharmaceutical expectations. Since 2019, the quality requirements for this category of drug products have also been clarified by the European Pharmacopoeia (Ph. Eur.). Similar to all products intended to prevent or treat diseases, LBPs will have to be registered as medicinal products to reach the market in the US and in Europe. In this area, regulatory authorities and the pharmaceutical industry will routinely use guidelines of the “International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use” (ICH). Although ICH guidelines are not legally binding, they provide very important recommendations, recognized by almost all drug authorities in the world. In this review, we discuss some aspects of this regulatory framework, especially focusing on products with an intended use in a diseased or vulnerable target population.Subject terms: Biological therapy, Biologics     

Cyclopropane chemistry. Part 5 [1,2]. Hexafluorocyclopropane as a source of difluorocarbene

Thermolysis of hexafluorocyclopropane in the presence of ethylene, propene, vinyl chloride, and vinyl bromide gives good yields of the corresponding 1,1-difluorocyclopropanes, formed by addition of difluorocarbene to the olefin. The tetrafluoroethylene formed dimerises to octafluorocyclobutane, co-dimerises with the olefin, or survives, depending on the reaction conditions. With allene, hexafluorocyclopropane gives 1-(difluoromethylene)cyclopropane, 2,2,3,3-tetrafluorospiropentane, and products derived from tetrafluoroethylene and allene.     

An integrated process for purification of lysozyme, ovalbumin, and ovomucoid from hen egg white

This article describes an integrated process for simultaneous purification of lysozyme, ovalbumin, and ovomucoid from hen egg white. The crude egg white extract was passed through a cation exchanger Streamline trade mark SP and the bound lysozyme was eluted with 5% ammonium carbonate, pH 9.0, containing 1 M NaCl after elution of avidin. This partially purified lysozyme was further purified 639-fold on dye-linked cellulose beads. Ovalbumin and ovomucoid did not bind to Streamline SP. Ovalbumin could be precipitated from this unbound fraction by 5% trichloroacetic acid, and ovomucoid was removed from the supernatant by precipitation with ethanol. The yields of lysozyme, ovomucoid, and ovalbumin were 77, 94, and 98%, respectively. All the purified proteins showed single bands on sodium dodecyl sulfate polyacrylamide gel electrophoresis. All the steps are easily scalable, and the process described here can be used for large-scale simultaneous purification of these proteins in the pure form.     

New nickel(II), copper(II), platinum(II) and palladium(II) complexes of a multidentate sulfur–nitrogen chelating agent

A new, potentially polydentate sulfur–nitrogen chelating agent, 2,6–bis(N-methyl-S-methyldithiocarbazato)pyridine (L) has been synthesized and characterized. With nickel(II) salts, the ligand yields complexes of empirical formula NiLX2·nH2O (X=Cl−, NCS− or NO3−; n=0 or 1) in which it behaves as a quadridentate NSSN chelating agent, coordinating to the nickel(II) ion via the two amino nitrogen atoms and the two sulfur atoms. Magnetic and spectral evidence support a distorted octahedral structure for these complexes. The ligand reacts with copper(II), platinum(II) and palladium(II) salts to yield homo-binuclear complexes of general formula [M2LX4]·nSol (M=CuII, PtII or PdII; X=Cl− or Br−; n=0.5, 1 or 2; Sol=H2O, MeOH or MeCOMe), in which each of the metal ions is in a square-planar environment. These complexes have been characterized by a variety of physicochemical techniques. This revised version was published online in June 2006 with corrections to the Cover Date.     

Synthesis, characterisation and evaluation of polydithiocarbamate resin supported on macroreticular styrene-divinylbenzene copolymer for the removal of trace and heavy metal ions

A new chelating resin was synthesised by the modification of styrene-divinylbenzene (2%) copolymer and incorporation of dithiocarbamate groups. The polydithiocarbamate resin was characterised by elemental analysis, thermal studies and IR studies. The analytical characteristics of the sorbent were established and optimum sorption conditions for Cu, Ni, Pb, Fe, As and Mn determined. The total sorption capacity of the resin was 37 mg g⁻¹ for Ni(II), 35 mg g⁻¹ for Cu(II), 29 mg g⁻¹ for Fe(III) and 23 mg g⁻¹ for Pb(II). The optimum pH for the removal of metal ions was 3-5 for Ni(II), 5 for Cu(II), 4 for Fe(III) and 4-5 for Pb(II). High sorption capacity was observed when compared with other conventional chelating polymers. The sorption kinetics was fairly rapid, as apparent from the loading half time t_1/2 values, indicating a better accessibility of the chelating sites.     

1H-pyrazolo[3,4-d]thieno[2,3-b]pyridine and its derivatives

The synthesis of the parent ring system and some of the derivatives of 1H-pyrazolo[3,4-d]thieno[2,3-b]pyridine are described.     

PERSONAL DOSIMETRY OF SOLAR UV RADIATION FOR DIFFERENT OUTDOOR ACTIVITIES

Abstract Quantifying individual exposure to ultraviolet radiation (UVR) is critical to understanding the etiology of a number of diseases including nonmelanotic and melanotic skin cancers. Measurements of personal exposure to solar UVR were made in Hobart, Tasmania in February (summer) 1991 for six different outdoor activities using UVR-sensitive polysulfone (PS) film attached at seven anatomical sites. Concurrent behavioral and environmental observations were also made. To date many studies have relied on subject recall to quantify past solar UVR exposures. To gain insight into the accuracy of subject recall the measured UVR exposures received by different subjects using the PS film were compared to those calculated from personal diaries and ambient solar UVB levels from a monitoring station. In general, when UVR exposure activities took place under close supervision, good correlations were obtained between the PS badges and the ambient measurements/diaries approach. Ultraviolet radiation exposures for the field study involving 94 subjects engaged in a number of outdoor activities are presented.