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Variation in the pigment content and phenolic composition of virgin olive oil from the olive cultivar Roghiani produced in Libya
No full textThe aim of this work was to determine the pigments content, colour characteristics, unsaponifiable matter as well as phenolic compounds of virgin olive oils (VOO) from the olive cultivar 'Roghiani', harvested in five different regions of northern Libya. The colour of virgin olive oils was evaluated by determining chlorophyll and carotenoids content, transparency values, and colour characteristics using CIE and CIE L*a*b*systems. In addition to the total phenols, content of single phenolic compounds were investigated, too. Obtained results indicated that the oil from Gharyan production region was quite different in relation to the oils from other harvest regions. Namely, this oil had not only the highest content of carotenoids, 9.15 +/- 0.21 mg/kg and high level of total chlorophylls, 37.7 +/- 1.89 mg/kg, but also a maximum content of phenols, 266.5 +/- 31.53 mgGAE/kg. Moreover, this is the first report on pigment investigation and colour characterisation in VOO from the 'Roghiani' cultivar produced in Libya in different harvest regions
Physico-chemical properties of low-fat cookies containing wheat and oat bran gels as fat replacers
No full textWheat and oat bran-based fat replacers in the form of gels were used for partial replacement of fat (30-50%) in a cookie formulation. Dough rheological properties, physical (cookie dimension, weight loss, moisture content and water activity), textural (hardness and fracturability), colour and sensory parameters were evaluated to characterize full-fat and fat-reduced cookies. Based on the obtained results it was concluded that the fat reduction in cookie formulation at the level of 30% maintained sensory properties of the full-fat cookies. Therefore, this level of fat replacement was chosen for further analysis: 30% WBG (wheat bran gel-containing cookies) and 30% OBG (oat bran gel-containing cookies) were examined in terms of nutritional and functional properties. It was revealed that fat replacement using bran gels at the level of 30% resulted in the fat-reduced added-value cookies in terms of dietary fibre, minerals and phenolics. 30% WBG cookies possessed higher dietary fibre, mineral and phenolic content in comparison to 30% OBG and the full-fat cookies
Development of voltammetric methods for antioxidant activity determination based on Fe(III) reduction
No full textNumerous methods have been developed for determination of antioxidant (AO) activity in vitro, but only several spectrophotometrical assays are frequently applied. Among them, probably the most simple is FRAP assay, based on the reduction of Fe(III) to Fe(II) by antioxidants. In this work the applicability of that reaction for the development of electrochemical method for AO activity determination was examined. The two common electrochemical techniques: direct current polarography and cyclic voltammetry on platinum working electrode were used. The developed fast, simple and without a need for the calibration against standard (such as Trolox or gallic acid) electrochemical methods were applied to determination of the AO activity of ten natural antioxidants. The AO activities determined by two developed methods and three frequently applied spectrophotometric assays (ABTS, DPPH and FRAP) correlated well. All the obtained correlation coefficients (R) were above 0.9. The cyclic voltammetric method fulfills green chemistry principles
Chemical structure and antifungal activity of mint essential oil components
No full textThe objective of this research was to determine chemical composition and to evaluate the antifungal activity of essential oil of Mentha piperita. By the application of GC/MS analysis of essential mint oil, 27 components were identified. The major components were menthol (39.9 %), menton (23.51 %), menthyl acetate (7.29 %), 1.8-cineol (5.96 %), isomenton (5.24 %), isomenthol (3.17 %), trans-caryophyllene (2.88 %), limonene (2.14 %), pulegon (1.38 %), beta-pinene (1.14 %) and piperiton (1.03 %). The quantitative structure-retention relationship (QSRR) was employed to predict the retention time (RT) of Mentha piperita essential oil compounds obtained in GC/MS analysis, using twelve molecular descriptors selected by genetic algorithm. The selected descriptors were used, as inputs of an artificial neural network, to build an RT predictive QSRR model. The coefficient of determination was 0.983, during training cycle, indicating that this model could be used for prediction of RT values for essential oil compounds in Mentha piperita essential oil extracts. Essential oil of Mentha piperita showed antifungal activity on all tested isolates in the minimal inhibitory concentration range of 0.2-1.7 mu l/ml and a minimal fungicidal concentration (MFC) range of 1.7-454.5 mu l/ml. The most powerful antifungal activity of mint was observed in C. cladosporioides of MFC value 1.7 mu l/ml. P. aurantiogriseum showed the lowest sensitivity of MFC value 454.5 mu l/ml
Modification of DC polarographic antioxidant assay-Application to aromatic plants and their active principles
No full textA direct current (DC) polarographic assay based on the decrease of anodic current of HydroxoPerhydroxoMercury (II) Complex (HPMC) formation in H2O2 solution in Clark Lubs (CL) buffer (pH 9.8) as working solution was previously applied to determine antioxidant (AO) capacity of water-soluble compounds. Here, the applicability of HPMC assay was extended into samples poorly soluble in water such as the essential oils and extracts of Lamiaceae and Apiaceae species obtained by ultrasound-assisted maceration (UAM) and Soxhlet extraction (SE) with 70 and 96% ethanol as well as individual compounds present. The influence of solvents miscible with water on HPMC anodic current was studied, and working solution was optimized. A modified HPMC method was applied to measure AO capacity of essential oils and extracts as well as compounds identified using gas chromatography-mass spectrometer (GC-MS) and gas chromatography with flame-ionization detection (GC-FID) (terpenoids and catechols) or known to be present (phenolic acids and flavonoids). A 1:1 mixture of CL buffer and ethanol was chosen as working solution. AO capacity of essential oils and extracts, established by modified HPMC assay, was in range of 1.2-2.0 and 9.2-38.4 (%/mL) while terpenoids and phenolics in range of 0.1-0.5 and 13.5-38.5 (%/mol), respectively. The superior AO capacity was ascribed to essential oils and extracts of Lamiaceae species and to extracts obtained with 70% ethanol. A higher AO capacity of extracts in comparison to essential oils was corroborated with a difference in phenolics and terpenoids capacity
One-Pot Combustion Synthesis of Nickel Oxide and Hematite: from Simple Coordination Compounds to High Purity Metal Oxide Nanoparticles
No full textThis work is the first report of a very simple and fast one-pot synthesis of nickel oxide (NiO) and hematite (alpha-Fe2O3) nanoparticles by thermal decomposition of transition metal aqua complexes with camphor sulfonate anions. Obtained nanopowders were characterized by X-ray powder diffraction, Fourier transform IR analysis, scanning electron microscopy, and Energy-dispersive X-ray spectroscopy. X-ray powder diffraction confirmed the formation of high purity NiO and alpha-Fe2O3 crystal phases. In the case of alpha-Fe2O3, about five times larger average crystallite size was obtained. Fourier transform IR spectra of synthesized materials showed characteristic peaks for NiO and alpha-Fe2O3 nanostructures. To visualize the morphology and the chemical composition of the final products Scanning electron microscopy and Energy-dispersive X-ray spectroscopy were performed. The thermogravimetric analysis was done for a better understanding of the general thermal behavior of precursor compounds. This easy-to-perform and fast preparation method opens a broad range of obtained materials' usage, particularly due to its economic viability
Structural study of L-ascorbic acid 2-phosphate magnesium, a raw material in cell and tissue therapy
No full textl-ascorbic acid 2-phosphate magnesium (APMg) salt is a vitamin C derivative frequently used as a raw material in cell and tissue therapy. APMg is not only used as a replacement of the unstable ascorbate, but also shows additional cell-biological functionalities. However, its unknown structural characteristics hamper the mechanistic elucidation of its biological role. Therefore, different techniques were applied for APMg structure characterization. Firstly, the stoichiometric composition was characterized by its solvent, ligand and magnesium content. No crystals of APMg could be obtained; however, a single crystal of APNa, the sodium salt of l-ascorbic acid 2-phosphate, was successfully obtained and its crystal structure was elucidated. FT-IR was applied to further clarify the structure of solid APMg. Finally, the structure of APMg in aqueous solution was explored by potentiometric titration as well as FT-IR. [GRAPHICS]
Anti-Virulence Potential and In Vivo Toxicity of Persicaria maculosa and Bistorta officinalis Extracts
No full textMany traditional remedies represent potential candidates for integration with modern medical practice, but credible data on their activities are often scarce. For the first time, the anti-virulence potential and the safety for human use of the ethanol extracts of two medicinal plants, Persicaria maculosa (PEM) and Bistorta officinalis (BIO), have been addressed. Ethanol extracts of both plants exhibited anti-virulence activity against the medically important opportunistic pathogen Pseudomonas aeruginosa. At the subinhibitory concentration of 50 mu g/mL, the extracts demonstrated a maximal inhibitory effect (approx. 50%) against biofilm formation, the highest reduction of pyocyanin production (47% for PEM and 59% for BIO) and completely halted the swarming motility of P. aeruginosa. Both extracts demonstrated better anti-quorum sensing and antibiofilm activities, and a better ability to interfere with LasR receptor, than the tested dominant extracts' constituents. The bioactive concentrations of the extracts were not toxic in the zebrafish model system. This study represents an initial step towards the integration of P. maculosa and B. officinalis for use in the treatment of Pseudomonas infections
Non-stoichiometric tungsten-carbide-oxide-supported Pt-Ru anode catalysts for PEM fuel cells - From basic electrochemistry to fuel cell performance
No full textDurability and cost of Proton Exchange Membrane fuel cells (PEMFCs) are two major factors delaying their commercialization. Cost is associated with the price of the catalysts, while durability is associated with degradation and poisoning of the catalysts, primarily by CO. This motivated us to develop tungsten-carbide-oxide (WxCyOz) as a new non-carbon based catalyst support for Pt-Ru-based anode PEMFC catalyst. The aim was to improve performance and obtain higher CO tolerance compared to commercial catalysts. The performance of obtained PtRu/WxCyOz catalysts was investigated using cyclic voltammetry, linear scan voltammetry and rotating disk electrode voltammetry. Particular attention was given to the analysis of CO poisoning, to better understand how WxCyOz species can contribute to the CO tolerance of PtRu/WxCyOz. Improved oxidation of COads at low potentials (E LT 0.5 V vs. RHE) was ascribed to OH provided by the oxide phase at the interfacial region between the support and the PtRu particles. On the other hand, at high potentials (E > 0.5 V vs. RHE) CO removal proceeds dominantly via OH provided from the oxidized metal sites. The obtained catalyst with the best performance (30% PtRu/WxCyOz) was tested as an anode catalyst in PEM fuel cell. When using synthetic reformate as a fuel in PEMFC, there is a significant power drop of 35.3 % for the commercial 30% PtRu/C catalyst, while for the PtRu/WxCyOz anode catalyst this drop is around 16 %
The effect of60co gamma irradiation on coal fly-ash geopolymer paste setting time
No full textCementation is the baseline technology for conditioning of low to intermediate level radioac-tive waste. Geopolymers, a class of alkali activated binders, are a promising new material for radioactive waste treatment. Coal fly-ash based geopolymers are a low-cost, low greenhouse gas footprint alternative to metakaolin based materials. Both the grouting of sludge/pow-ders/liquids and encapsulation of solids/compacted waste rely on the grout maintaining opti-mal flow (rheological properties) during the mixing and pouring operations, and achieving a set leading to proper long term solidification (mechanical properties). The initial and final setting time for fly-ash geopolymer paste, based on the SRPS EN 196-3 standard, has been measured upon irradiation by gamma rays in a60Co reference field positioned with a kerma air rate of 3.42 mGys–1. The binder paste was prepared using fly-ash from the TENT B power plant's electrostatic filters without further sieving, activated by water glass with module 1.5 and mixed with distilled water until a satisfactory flow was obtained, and poured into the sample and control molds. The initial and final setting times for the irradiated sample and non-irradiated control were determined by the Vicat apparatus. The irradiated sample dem-onstrated an 11 % shorter initial setting time, and 16 % shorter final setting time, compared to the control