Evaluation of flavonoids and furanocoumarins from Citrus bergamia (Bergamot) juice and identification of new compounds

Bergamot juice (BJ) contains different classes of flavonoids (e.g. flavanones and flavones) that can exert beneficial effects on human health. The aim of this study was to evaluate the qualitative and quantitative composition of a BJ obtained from fruits harvested in Southern Italy (Calabria) at the end of their maturation period. The identity of several flavonoids and furanocoumarins was assessed by co-chromatography, UV spectra and molecular weight comparison. The unknown compounds were dissociated by induced collision (CID-MS) and their identity established through the characteristic ions product. By this approach a complete profile of about twenty compounds (furano-coumarins, flavonoids C- and O-glycosides) present in BJ was obtained. Furthermore, three acylated flavanones, present in amounts of 20.1+/-1.1, 89.3+/-2.2 and 190.1+/-3.1 mg/L, respectively, and which seem to correspond to di-oxalate derivatives of neoeriocitrin, naringin and neohesperidin, were identified for the first time in BJ. The other main flavanones were naringin, neohesperidin and neoeriocitrin, and their content was 167.5+/-1.8, 123.9+/-1.7 and 73.3+/-1.6 mg/L, respectively. Concerning flavones, the total amount in BJ was about 160 mg/L and the main ones were vicenin-2, stellarin-2, rhoifolin and neodiosmin. Bergapten and bergamottin were the primary furanocoumarins in BJ and their amounts were 9.0+/-0.4 and 18.2+/-0.5 mg/L, respectively.     

Pharmaceutical analysis by supercritical fluid chromatography: Optimization of the mobile phase composition on a 2-ethylpyridine column

The separation of neutral, acidic, and basic pharmaceuticals with diverse physicochemical properties by packed column supercritical fluid chromatography (pSFC) on a 2-ethylpyridine column (25 cmx4.6 mm id, 3 mum particles) is presented. The optimization strategy involved separations at 100% methanol (MeOH) and at 50% MeOH/50% ACN while keeping the peak symmetry additives formic acid (FA) and isopropylamine (IPA) at constant levels of 0.25% v/v. By plotting the adjusted retention times as a function of the MeOH/ACN ratio, an optimal modifier ratio composition of 65% MeOH/35% ACN was found. The total set of 26 neutral, acidic, and basic pharmaceuticals was analyzed and the optimal composition experimentally verified. This mobile phase composition is currently used in pharmaceutical method development and open-access generic screening environments.     

Synthesis, redox, and amphiphilic properties of responsive salycilaldimine-copper(II) soft materials

Hydrolysis of the asymmetric pyridine- and phenol-containing ligand HL (1) (2-hydroxy-4-6-di- tert-butylbenzyl-2-pyridylmethyl)imine) led to the use of bis-(3,5-di -tert-butyl-2-phenolato-benzaldehyde)copper(II), [Cu (II)(L (SAL)) 2] ( 1) as a precursor for bis-(2,4-di- tert-butyl-6-octadecyliminomethyl-phenolato)copper(II), [Cu (II)(L (2)) 2] ( 3), bis-(2,4-di- tert-butyl-6-octadecyl aminomethyl-phenolato)copper(II), [Cu (II)(L (2A)) 2] ( 3'), and bis-(2,4-di- tert-butyl-6-[(3,4,5-tris-dodecyloxy-phenylimino)-methyl]-phenolato)copper(II), [Cu (II)(L (3)) 2] ( 4). These complexes exhibit hydrophilic copper-containing head groups, hydrophobic alkyl and alkoxo tails, and present potential as precursors for redox-responsive Langmuir-Blodgett films. All systems were characterized by means of elemental, spectrometric, spectroscopic, and electrochemical techniques, and their amphiphilic properties were probed by means of compression isotherms and Brewster angle microscopy. Good redox activity was observed for 3 with two phenoxyl radical processes between 0.5 and 0.8 V vs Fc (+)/Fc, but this complex lacks amphiphilic behavior. To attain good balance between redox response and amphiphilicity, increased core flexibility in 3' and incorporation of alkoxy chains in 4 were attempted. Film formation with collapse at 14 mN.m (-1) was observed for the alkoxy-derivative but redox-response was seriously compromised. Core flexibility improved Langmuir film formation with a higher formal collapse and showed excellent cyclability of the ligand-based processes.     

Structural and electronic properties of the [FeFe] hydrogenase H-cluster in different redox and protonation states. A DFT investigation

The molecular and electronic structure of the Fe 6S 6 H-cluster of [FeFe] hydrogenase in relevant redox and protonation states have been investigated by DFT. The calculations have been carried out according to the broken symmetry approach and considering different environmental conditions. The large negative charge of the H-cluster leads, in a vacuum, to structures different from those observed experimentally in the protein. A better agreement with experimental data is observed for solvated complexes, suggesting that the protein environment could buffer the large negative charge of the H-cluster. The comparison of Fe 6S 6 and Fe 2S 2 DFT models shows that the presence of the Fe 4S 4 moiety does not affect appreciably the geometry of the [2Fe] H cluster. In particular, the Fe 4S 4 cluster alone cannot be invoked to explain the stabilization of the mu-CO forms observed in the enzyme (relative to all-terminal CO species). As for protonation of the hydrogen cluster, it turned out that mu-H species are always more stable than terminal hydride isomers, leading to the conclusion that specific interactions of the H-cluster with the environment, not considered in our calculations, would be necessary to reverse the stability order of mu-H and terminal hydrides. Otherwise, protonation of the metal center and H 2 evolution in the enzyme are predicted to be kinetically controlled processes. Finally, subtle modifications in the H-cluster environment can change the relative stability of key frontier orbitals, triggering electron transfer between the Fe 4S 4 and the Fe 2S 2 moieties forming the H-cluster.     

New chiral and restricted-access materials containing glycopeptides as selectors for the high-performance liquid chromatographic determination of chiral drugs in biological matrices

Two new chiral and restricted-access materials containing glycopeptide antibiotics as chiral selectors (chiro-Glyco-RAM) were designed, suitable for the direct HPLC injection of biological fluids containing chiral drugs without any sample pre-treatment or pre-columns coupling. The external surface of the porous silica support was covered with a bio-compatible hydrophilic polymeric network (polyvinyl alcohol, PVA) while the chiral phase based on either teicoplanin (TE) or teicoplanin aglycone (TAG) was exclusively confined to the internal region. The chiro-Glyco-RAM supports were synthesized by the following steps: (a) introduction of 3-aminopropyl groups on 100 A pore size silica gel; (b) activation of the aminopropylated silica with 1,6-diisocyanatohexane; (c) functionalization of the external region of the porous silica with PVA; (d) covalent linking of TE/TAG to the internal surface. The average pore diameter of the chiro-Glyco-RAM supports, calculated by inverse size-exclusion chromatography (ISEC), was about 80 A and able to exclude macromolecules heavier than about 20,000 Da (such as the most abundant serum proteins) from the pores. The recovery of bovine serum albumin (BSA) was almost quantitative. HPLC analyses of model chiral drugs were performed using hydro-organic mobile phases consisting of an organic solvent (acetonitrile or methanol) and aqueous solutions of ammonium acetate (0.020 M) or ammonium formate (0.0025-0.0050 M).     

Isometric actions on spheres with an orbifold quotient

Mathematische Annalen - We classify representations of compact connected Lie groups whose induced action on the unit sphere has the orbit space isometric to a Riemannian orbifold.     

Synthesis and electrochemical investigation of <Emphasis Type="Italic">beta</Emphasis>-substituted thiophene-based donor–acceptor copolymers with 3,4-ethylenedioxythiophene (EDOT)

The present work reports the synthesis of four electron-acceptor beta-substituted thiophenes that were studied as monomers for electrochemical polymerization with 3,4-ethylenedioxythiophene (EDOT), an electron-donating monomer, aiming the combination of electron-acceptor and donor monomer thiophene to a simpler and convenient build up of novel donor–acceptor copolymeric materials via electrochemical polymerization. Four novel copolymers poly(EDOT-co-3-thiophene phenylacetate), (PEDOT-co-PPhTAc-2a), poly(EDOT-co-3-thiophene(4-nitrophenyl)acetate) (PEDOT-co-PPhTAc-2b), poly(EDOT-co-3-thiophenephenylcarboxylate) (PEDOT-co-PPhTCb), and poly(EDOT-co-3-(phenoxymethyl)thiophene) (PEDOT-co-PPhOMT) were electrochemically polymerized. The monomers were characterized by spectrometric techniques (FTIR, ¹H NMR, and ¹³C NMR), and the copolymers were identified by electrochemical analyses and FT-IR. Although the corresponding homopolymers could not be obtained, in the presence of EDOT, the copolymers were formed in a quasi-reversible electrochemical kinetics. The infrared spectra of the copolymers as well the electrochemical profile corroborates their obtaining. The mass variation during the electrosynthesis was analyzed using a quartz crystal microbalance. The film’s morphologies were investigated by SEM. Interestingly, the combination of electron-rich monomer thiophene (EDOT) and these electron-deficient carboxy-substituted thiophenes might be a convenient building block couple to increase the performance control of physic-chemical properties of mixed polythiophenes with innovative applications and they also showed a possible applicability as charge storage device.     

An evaluation of british columbian beetle-killed hybrid spruce for bioethanol production

The development of bioconversion technologies for production of fuels, chemicals, and power from renewable resources is currently a high priority for developed nations such as the United States, Canada, and the European Union as a way to improve national energy security and reduce greenhouse gas emissions. The widespread implementation of such technologies will require a sustainable supply of biomass from forestry and agriculture. Forests are a major source of feedstocks for biofuels production in Canada. Woody biomass includes residues from logging and forest thinning, and from wood processing and pulp production. More recently, damaged wood caused by beetle infestations has become available on a large scale in Western Canada. This study evaluates beetle-killed British Columbian hybrid spruce (HS) (Picea glauca x P. engelmannii) as a feedstock for the production of bioethanol. In the past 30 yr, attack by the beetle Dendroctonus rufipennis and associated fungi has resulted in estimated losses of more than three billion board feet in British Columbia alone. Here we describe the chemical and some physical characteristics of both healthy (HHS) and beetle-killed (BKHS) British Columbian HS and evaluate the technical feasibility of using these feedstocks as a source of biomass for bioethanol production. Untreated HHS and BKHS did not differ significantly in chemical composition except for the moisture content, which was significantly lower in BKHS (approx 10%) compared with HHS (approx 18%). However, the yields of carbohydrates in hydrolyzable and fermentable forms were higher at mild pretreatment conditions (H-Factor <1000) for BKHS compared with HHS. At medium (H-Factor 1000-2000) and severe (H-Factor >2000) pretreatment conditions HHS and BKHS behaved similarly. Organosolv pretreated HHS and BKHS demonstrated good ethanol theoretical yields, approx 70 and 80%, respectively.     

Unraveling solvent-driven equilibria between alpha- and 3(10)-helices through an integrated spin labeling and computational approach

In this work we present an effective and flexible computational approach, which is the result of an ongoing development in our groups, allowing the complete a priori simulation of the ESR spectra of complex systems in solution. The usefulness and reliability of the method are demonstrated on the very demanding playground represented by the tuning of the equilibrium between 3(10)- and alpha-helices of polypeptides by different solvents. The starting point is the good agreement between computed and X-ray diffraction structures for the 3(10)-helix adopted by the double spin-labelled heptapeptide Fmoc-(Aib-Aib-TOAC)2-Aib-OMe. Next, density functional computations, including dispersion interactions and bulk solvent effects, suggest another energy minimum corresponding to an alpha-helix in polar solvents, which, eventually, becomes the most stable structure. Computation of magnetic and diffusion tensors provides the basic ingredients for the building of complete spectra by methods rooted in the Stochastic Liouville Equation (SLE). The remarkable agreement between computed and experimental spectra at different temperatures allowed us to identify helical structures in the various solvents. The generality of the computational strategy and its implementation in effective and user-friendly computer codes pave the route toward systematic applications in the field of biomolecules and other complex systems.     

Exploring the subtleties of drug-receptor interactions: the case of matrix metalloproteinases

By solving high-resolution crystal structures of a large number (14 in this case) of adducts of matrix metalloproteinase 12 (MMP12) with strong, nanomolar, inhibitors all derived from a single ligand scaffold, it is shown that the energetics of the ligand-protein interactions can be accounted for directly from the structures to a level of detail that allows us to rationalize for the differential binding affinity between pairs of closely related ligands. In each case, variations in binding affinities can be traced back to slight improvements or worsening of specific interactions with the protein of one or more ligand atoms. Isothermal calorimetry measurements show that the binding of this class of MMP inhibitors is largely enthalpy driven, but a favorable entropic contribution is always present. The binding enthalpy of acetohydroxamic acid (AHA), the prototype zinc-binding group in MMP drug discovery, has been also accurately measured. In principle, this research permits the planning of either improved inhibitors, or inhibitors with improved selectivity for one or another MMP. The present analysis is applicable to any drug target for which structural information on adducts with a series of homologous ligands can be obtained, while structural information obtained from in silico docking is probably not accurate enough for this type of study.