Targeting the IspD Enzyme in the MEP Pathway: Identification of a Novel Fragment Class

The enzymes of the 2-C-methylerythritol-d -erythritol 4-phosphate (MEP) pathway (MEP pathway or non-mevalonate pathway) are responsible for the synthesis of universal precursors of the large and structurally diverse family of isoprenoids. This pathway is absent in humans, but present in many pathogenic organisms and plants, making it an attractive source of drug targets. Here, we present a high-throughput screening approach that led to the discovery of a novel fragment hit active against the third enzyme of the MEP pathway, PfIspD. A systematic SAR investigation afforded a novel chemical structure with a balanced activity–stability profile ( 16 ). Using a homology model of PfIspD, we proposed a putative binding mode for our newly identified inhibitors that sets the stage for structure-guided optimization.     

Design of microalgal biomass production in a continuous photobioreactor: An integrated experimental and modeling approach

The industrial production of microalgae in continuous photobioreactors (PBRs) was investigated using an integrated experimental-modeling approach.     

Antioxidant synergism between fruit juice and <Emphasis Type="Italic">α</Emphasis>-tocopherol. A comparison between high phenolic black chokeberry (<Emphasis Type="Italic">Aronia melanocarpa</Emphasis>) and high ascorbic blackcurrant (<Emphasis Type="Italic">Ribes nigrum</Emphasis>)

Black chokeberry juice (Aronia melanocarpa, Elliot), blackcurrant juice (Ribes nigrum, Ben Lomond) and α-tocopherol were found to protect phosphatidyl choline against oxidation in a peroxidating liposome system as evidenced by lag phases for formation of conjugated dienes. When present together, black chokeberry juice and α-tocopherol showed a clear synergistic effect on the length of the lag phase, while effects of blackcurrant juice and α-tocopherol were additive. The concentration of total phenolics in black chokeberry juice was six times higher than in blackcurrant juice (gallic acid equivalents). Ascorbic acid corresponded to 1% of total phenolics in black chokeberry juice and 10% in blackcurrant juice. Based on the length of the lag phase, the phenolics present in black chokeberry were on an average, twice efficient as scavengers of lipid peroxyl radicals as phenolics in blackcurrant. Black chokeberry was by HPLC analysis of peroxidating liposomes, in contrast to blackcurrant, found to protect α-tocopherol efficiently against oxidation to the end of the lag phase. The phenolics present in black chokeberry juice were concluded to be more efficient in regenerating or protecting α-tocopherol than ascorbic acid or the phenolics in blackcurrant. As for the phenolics, this was further evidenced by ranking of their radical scavenging activity as studied by ESR-spectroscopy.     

Effect of formulation on physicochemical properties and water status of nutritionally enhanced tortillas

BACKGROUND: Various nutritionally enhanced tortillas were developed by incorporating ingredients with nutritional functionality (carrot, soy, wholemeal kamut and their combination (CSK)) in a standard wheat tortilla formulation. The effect of these ingredients on the physicochemical properties and water status of the products was evaluated. RESULTS: Partial substitution of carrot juice for water in the tortilla formulation significantly reduced the macroscopic (water activity and moisture content) and thermal (‘frozen’ water (FW) content) properties and marginally reduced the ¹H molecular mobility (faster ¹H free induction decay (FID)) compared with the standard. Wholemeal kamut increased the FW content via a possible water redistribution among ingredients. Whole soy flour induced higher ¹H molecular mobility (T_2B relaxation rate, % ¹H T_2B population and single T₁), probably because a loose soy protein—water interaction and/or margarine. The water status of the CSK tortilla reflected the contribution of each ingredient in the respective prototype: fast ¹H FID (carrot), high FW content (kamut), high ¹H molecular mobility and low moisture content and water activity (soy). CONCLUSIONS: The changes in formulation used in this study to produce tortillas with enhanced nutritional value affected the water status of the products in a very interesting manner: the different ingredients altered the water status at different levels. Copyright © 2008 Society of Chemical Industry     

Effects of industrial processing on the distributions of deoxynivalenol, cadmium and lead in durum wheat milling fractions

The aim of this work was to investigate the distributions of deoxynivalenol, cadmium and lead in durum wheat milling fractions from industrial milling plants. The study focused on two milling technologies: conventional milling and debranning before milling. Initial analyses of samples of all raw materials showed contamination levels considerably lower than the limits imposed by the European Commission. Deoxynivalenol, cadmium and lead showed rather similar patterns of distribution. Semolina had lower, although not significant levels of these undesirable substances than unprocessed wheat grain; in contrast, marked concentration factors were found for the contaminants in shorts (middlings) and flour shorts. Debranning technology resulted in higher contamination levels in products intended for animal feed than conventional milling. The difference was statistically significant for deoxynivalenol and lead contamination of the shorts (middlings) fraction. As the outer parts of the kernel are generally considered richer in inorganic elements and moulds, Pearson's correlation was performed to investigate the relationship between the crude fibre contents of the different fractions, adopted as bran marker, and contaminant levels. Positive correlations were found for each of the three contaminants, although the correlation coefficients were not very high, demonstrating that crude fibre likely does not constitute a good marker for describing contaminants repartitioning in milling fractions when the levels of these substances are low.     

Influence of the structure of soft and stiff chain fragments on properties of segmented polyurethanes. I. Phase morphology

Model segmented polyurethanes (SPUs) prepared from either oxypropylene glycol oligomer or butylene adipate glycol oligomer, both of molar mass 2 kg/mol (soft fragments, SFT), and three different diisocyanates (all-trans 4,4'-dicyclohexylmethane diisocyanate, t, t-HMDI-1.0; HMDI with 20% of trans isomers, t, t-HMDI-0.2; and 4, 4'-diphenylmethane diisocyanate, MDI) (stiff fragments, STF) were characterized by specific heat capacity measurements in the temperature interval 140-540 K, and by wide-angle and small-angle X-ray scattering at room temperature. Limited miscibility of SFT and STF chain components resulted in incomplete separation into a regular three-dimensional macrolattice of STF-rich microdomains and SFT-rich microphases. The composition of STF-rich microdomains was estimated by fitting the softening temperatures to the Couchman's equation, whereas the relative contents of SFT-rich and STF-rich microphases were assessed by comparing the specific heat capacity change at the glass transition temperatures to corresponding additive values. The overall degree of microphase separation, as well as the mean macrolattice spacings between STF microdomains decreased in the order, MDI > t, t-HMDI-1.0 ? t, t-HMDI-0.2. The conformation of STF fragments within the STF-rich microdomains changed from nearly extended (for MDI) through slightly contracted (for t, t-HMDI-1.0) to strongly contracted (for t, t-HMDI-0.2).     

Amino-p-benzoquinone Adducts and Polymers as Adhesion Promoters for Steel

Phenolic and quinonoid compounds are widely studied in biological sciences because of their ability to chelate heavy metals like iron and copper and recently have found new applications in synthetic macromolecules. Amino-p-benzoquinone polymers, poly[(2,5-hexamethylenediamino)-1,4-benzoquinone] and poly{[2,5-(2,2′-bistrifluoromethyl)-4,4′-biphenylenediamino]1,4-benzoquinone} were synthesized and evaluated as adhesion promoters for steel/epoxy joints. An improvement in the torsional shear strength of these joints was observed when these polymers were used as adhesion promoters. The durability of the adhesive bond was also improved after boiling water treatment, relative to untreated and silane-treated joints. The improvement in adhesion could be attributed to the formation of a chelate between the polyaminoquinone (PAQ) and the iron surface and a chemical reaction between the PAQ and the epoxy resin. A low molecular weight model compound, bis[2,5-(4-methylanilido)]-1,4-benzoquinone, was also used to study coupling between the epoxy adhesive and the steel surface. Electron spin resonance (ESR), atomic absorption spectroscopy and infrared spectroscopy were used to document the epoxy-coupling agent reaction and the chelate formation.     

Oxygen‐ and light‐barrier properties of thermoformed packaging materials used for modified atmosphere packaging. evaluation of performance under realistic storage conditions

The oxygen transmission rate (OTR) of packaging materials used for modified atmosphere packaging (MAP) of chilled products varies extensively with temperature, relative humidity (RH) and material thickness after the thermoforming of packages. Two different polymer combinations were studied: APET/PE (tray) and PA/PE (lid). A temperature reduction of 8°C (in the interval 7–23°C) caused an OTR reduction of 26–48% depending on material type, degree of thermoforming and RH. A 2–3‐fold increase in OTR was observed for PA/PE film when measured at 100/100% RH compared to 0/100% RH, whereas the APET/PE trays were not affected by RH. Increased OTR was observed as a result of material thinning; however, the increase was not always directly proportional to the degree of material thinning. Even very small amounts of oxygen have, in combination with light exposure, significant effects on oxidative quality deterioration of many products. Consequently, the changes in OTR observed in this study emphasize the necessity of evaluating the performance of packaging materials under realistic storage conditions, in order to estimate the real oxygen content of a chosen package solution. The light transmission through the packaging material was found to be reduced to 0–30% (300–800 nm) by dyeing of the lid and/or addition of labels. Thus, it is easy to protect the products from light, at least partly. Copyright © 2005 John Wiley & Sons, Ltd.