Pomegranate oil as a valuable pharmaceutical and nutraceutical

Pomegranate oil is the unique edible oil produced from the seed of the pomegranate fruit (Punica granatum L.), which can be extracted by various methods including supercritical CO₂, superheated hexane, cold pressing, microwaves and ultrasound. The oil composition of pomegranate seed has received particular attention recently due to its content of antioxidant and anticancer agents, which may be important components for the production of new medicines and cosmetics.     

Young adults and the decline of the urban English pub: issues for planning

The numbers of English public houses or “pubs” have reduced significantly in the last two decades. Politicians have called on the planning system to resist their closure but, at the same time, demand further controls over high-street bars. This paper explores the reasons for the decline and the rationale for supporting the continuation of the “traditional” English pub. Using evidence drawn from a wider study of the relationships between places and youth drinking cultures, the paper discusses young adults' use of pubs. While recognising the adverse effects of heavy drinking, arguments are put forward in support of the traditional pub as a site for restrained and responsible social interaction for young adults. The paper discusses the issues this raises for the UK planning system in the context of responsibilities for social sustainability and public health.     

Mechanisms of Enhanced Catalysis in Enzyme–DNA Nanostructures Revealed through Molecular Simulations and Experimental Analysis

Understanding and controlling the molecular interactions between enzyme substrates and DNA nanostructures has important implications in the advancement of enzyme–DNA technologies as solutions in biocatalysis. Such hybrid nanostructures can be used to create enzyme systems with enhanced catalysis by controlling the local chemical and physical environments and the spatial organization of enzymes. Here we have used molecular simulations with corresponding experiments to describe a mechanism of enhanced catalysis due to locally increased substrate concentrations. With a series of DNA nanostructures conjugated to horseradish peroxidase, we show that binding interactions between substrates and the DNA structures can increase local substrate concentrations. Increased local substrate concentrations in HRP(DNA) nanostructures resulted in 2.9‐ and 2.4‐fold decreases in the apparent Michaelis constants of tetramethylbenzidine and 4‐aminophenol, substrates of HRP with tunable binding interactions to DNA nanostructures with dissociation constants in the micromolar range. Molecular simulations and kinetic analysis also revealed that increased local substrate concentrations enhanced the rates of substrate association. Identification of the mechanism of increased local concentration of substrates in close proximity to enzymes and their active sites adds to our understanding of nanostructured biocatalysis from which we can develop guidelines for enhancing catalysis in rationally designed systems.     

16—THE PREPARATION,FINE STRUCTURE,AND PHYSICAL PROPERTIES OF PARTLY METHYLATED COTTON FABRICS

Cotton fabric has been methylated under a variety of conditions. The extent of methylation has been shown to be dependent on the time of methylation and on the degree of swelling or disruption of structure. The latter is caused by the alkali pretreatment or by the swelling of the partly methylated cellulose. Fabric physical properties have been measured and the influence of the methylation treatment has been examined.     

SUPERCRITICAL AND SUB-CRITICAL FLUID SOLVENT EFFECTS ON A DIELS-ALDER REACTION

The effect of pressure on the measured bimolecular rate constant of the Diels-Alder reaction between maleic anhydride and isoprene was investigated in supercritical CO₂ and sub-critical propane. The reaction was carried out at 35°C in CO₂ and 80°C in propane. Measured bimolecular rate constants are also compared to predictions from the thermodynamic pressure effect using transilion state theory and the Peng-Robinson equation of state. The rate constants in supercritical C0₂ agreed closely with the thermodynamic pressure effect predictions over the entire pressure range. Furthermore, the mole fraction based rate constants were found to vary linearly with the density of the solution. The rate constants in the sub-critical propane solvent significantly diverged from the thermodynamic pressure effect predictions and were found to deviate from this linear density dependence at the lower pressures studied. The results are interpreted in the context of local reactant concentrations about the reacting maleic anhydride and solvent-solute and cosolvent-solute interactions.     

Assessment of compositional changes during ripening of transgenic papaya modified for protection against papaya ringspot virus

BACKGROUND: Papaya (Carica papaya L.) production is limited by over 20 viruses, the most damaging of which is papaya ringspot virus (PRSV). Owing to a lack of suitable PRSV‐resistant sources in Carica germplasm, transgenic resistance using the coat protein (cp) gene of a local PRSV strain is being developed to manage the disease in Jamaica. For assurance of food safety, the nutritional and antinutritional composition of transgenic papayas during ripening was compared with that of unmodified control samples. RESULTS: Mature unripe fruits of transgenic and non‐transgenic papayas were repeatedly harvested and stored at room temperature for 1 week periods, during which random samples were assessed. With the exception of one transgenic line, no significant differences (P > 0.05) were observed in selected nutrients and antinutrients between the control and test samples at three stages of maturity, although a few random variations were noted. CONCLUSION: Transformation with viral cp gene and two marker genes did not produce any major unintended alterations in either the nutritional or the antinutritional composition of transgenic papayas. These findings must be compared with other physicochemical and safety assessments to provide a scientific basis for concluding substantial equivalence with conventional papayas available on the market in Jamaica. Copyright © 2008 Society of Chemical Industry     

Arsenic removal with iron(II) and iron(III) in waters with high silicate and phosphate concentrations

Arsenic removal by passive treatment, in which naturally present Fe(II) is oxidized by aeration and the forming iron(III) (hydr)oxides precipitate with adsorbed arsenic, is the simplest conceivable water treatment option. However, competing anions and low iron concentrations often require additional iron. Application of Fe(II) instead of the usually applied Fe(III) is shown to be advantageous, as oxidation of Fe(II) by dissolved oxygen causes partial oxidation of As(III) and iron(III) (hydr)oxides formed from Fe(II) have higher sorption capacities. In simulated groundwater (8.2 mM HCO3(-), 2.5 mM Ca2+, 1.6 mM Mg2+, 30 mg/L Si, 3 mg/L P, 500 ppb As(III), or As(V), pH 7.0 +/- 0.1), addition of Fe(II) clearly leads to better As removal than Fe(III). Multiple additions of Fe(II) further improved the removal of As(II). A competitive coprecipitation model that considers As(III) oxidation explains the observed results and allows the estimation of arsenic removal under different conditions. Lowering 500 microg/L As(III) to below 50 microg/L As(tot) in filtered water required > 80 mg/L Fe(III), 50-55 mg/L Fe(II) in one single addition, and 20-25 mg/L in multiple additions. With As(V), 10-12 mg/L Fe(II) and 15-18 mg/L Fe(III) was required. In the absence of Si and P, removal efficiencies for Fe(II) and Fe(III) were similar: 30-40 mg/L was required for As(II), and 2.0-2.5 mg/L was required for As(V). In a field study with 22 tubewells in Bangladesh, passive treatment efficiently removed phosphate, but iron contents were generally too low for efficient arsenic removal.     

Reactions of co-adsorbed carbon dioxide and dioxygen at the Mg(0001) surface at low temperatures

X-ray photoelectron spectroscopy has established that molecular dioxygen states are stabilised at a Mg(0001) surface in the presence of physisorbed carbon dioxide at 80 K. The dioxygen–CO₂ complex is highly reactive with low energy reaction pathways to carbonate formation; the latter is subsequently reduced to give surface carbide and oxide at a temperature below 150 K. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of substitution of Thr63 by alanine on the structure and function of Lactobacillus casei dihydrofolate reductase

A mutant of Lactobacillus casei dihydrofolate reductase hasbeen constructed in which Thr63, a residue which interacts withthe 2'-phosphate group of the bound coenzyme, is replaced byalanine. This substitution does not affect k_cat, but producesan 800-fold increase in the K_m for NADPH, which reflects dissociationof NADPH from the enzyme-NADPH-tetrahydrofolate complex, anda 625-fold increase (corresponding to 3.8 kcal/mol) in the dissociationconstant for the enzyme-NADPH complex. The difference in magnitudeof these effects indicates a small effect of the substitutionon the negative cooperativity between NADPH and tetrahydrofolate.Stopped-flow studies of the kinetics of NADPH binding show thatthe weaker binding arises predominantly from a decrease in theassociation rate constant. NMR spectroscopy was used to comparethe structures of the mutant and wild-type enzymes in solution,in their complexes with methotrexate and with methotrexate andNADPH. This showed that only minimal structural changes resultfrom the mutation; a total of 47 residues were monitored fromtheir resolved ¹H resonances, and of these nine in the binarycomplex and six in the ternary differed in chemical shift betweenmutant and wild-type enzyme. These affected residues are confinedto the immediate vicinity of residue 63. There is a substantialdifference in the ³¹P chemical shift of the 2'-phosphate ofthe bound coenzyme, reflecting the loss of the interaction withthe side chain of Thr63. The only changes in nuclear Overhausereffects (NOEs) observed were decreases in the intensity of NOEsbetween protons of the adenine ring of the bound coenzyme andthe nearby residues Leu62 and Ile102, showing that the substitutionof Thr63 does cause a change in the position or orientationof the adenine ring in its binding site.