Polyphenols have many beneficial pharmacological properties, as a result of which they have been the subject of intensive studies. The most conventional techniques described here can be divided into three groups: (i) methods used for screening (in-situ methods); (ii) methods used to gain insight into the mechanisms of polyphenol–protein interactions; and (iii) methods used to study protein aggregation and precipitation. This review will give a brif insight in computational metods and biosensors and cell-based methods, spectroscopic methods including fluorescence emission, UV-vis adsorption, circular dichroism, Fourier transform infrared and mass spectrometry, nuclear magnetic resonance, X-ray diffraction, and light scattering techniqes including small-angle X-ray scattering and small-angle neutron scattering), and calorimetric techniques (isothermal titration calorimetry and differentiall scanning calorimetry), microscopy, the techniques which have been successfully used for polyphenol-protein interactions. At the end the new methods based on single molecule detection with high potential to study polyphenol-protein interactions will be presented.
COBISS.SI-ID: 4537208
The leaves of the hop plant (Humulus lupulus L.) are an agricultural by-product that is not exploited but could also be used as a source of phenolic compounds. This study compared two hop cultivars from four different hop-growing regions (Žalec, Slovenia; Leutschach (Kranach), Austria; Hüll, Germany; Žatec, Czech Republic): cv. ‘Aurora’ and cv. ‘Hallertauer Magnum’ three years in succession (2008-2010). The leaves had 3-fold to 30-fold less total phenolics than the cones, and much lower antioxidant activity regardless of the year and of the growing location. The best reducer was the extract from the Aurora leaves collected in the Czech Republic in 2010. Antimicrobial activity was extraordinary for all hop cones extracts against gram positive Staphylococcus aureus and moderate antimicrobial activity for hop cones and leaves extracts against gram negative Escherichia coli O157:H7. The results of a phenolic profile analyses showed a big difference between the leaves and cones for an unidentified peak with tr =35.1 min. The cones had no peak with such retention time.
COBISS.SI-ID: 4453496
Dielectric spectroscopy at low frequencies was applied to analyze vegetable oils, in particular roasted pumpkin seed oils (RPO). Large differences were observed for electrical conductivity not previously applied as a tool in the analysis of crude vegetable oils. RPO have two orders of magnitude higher conductivity than refined sunflower oils and extra virgin olive oils. Differences in dielectric constant were small and influenced by fatty acid composition and presence of minor components. The conductivity of pumpkin seed oils is highly correlated to phospholipid and metal contents. Phospholipids, magnesium, potassium and sodium are present at mmol/kg concentrations as determined by ICP-MS. We have shown that measurement of electrical conductivity can be used as a cost efficient method to detect adulteration of RPO with refined oils, even for those with similar fatty acid composition. Low background conductivity of triacylglycerols allows that even trace amounts of metals and phospholipids are detected in vegetable oils.
COBISS.SI-ID: 4512632
Bilberries processed into spreads can be important sources of anthocyanins through the whole year if they remain rich in the final product. In the published article it was proven that less anthocyanins were degraded during thermal processing of non-ground and ground bilberries by industrial than by home-made procedure, mostly due to the presence of oxygen. Both spreads had two fold more phenolic acids and flavanols. For this reson three products of anthocyanin degradation were tested as possible markers. It was proven that only one reflected well the anthocyanin degradation and that industrial spread procedure with non-ground bilberries is more suitable procedure for the final content of anthocyanins and other phenolics in the spread than the home-made one.
COBISS.SI-ID: 4437368
Pernisine is an extracellular serine protease from the hyperthermophilic Archaeon Aeropyrum pernix K1. Low yields from the natural host and expression problems in heterologous hosts have limited the potential applications of pernisine in industry. The challenges of pernisine overexpression in Escherichia coli were overcome by codon preference optimisation and de-novo DNA synthesis. The following forms of the pernisine gene were cloned into the pMCSGx series of vectors and expressed in E. coli cells: wild-type (pernisinewt) and codon-optimised (pernisineco). Pernisine was expressed and purified as 55-kDa proforms with yields of around 10 mg per litre E. coli culture. After heat activation of purified pernisine, the proteolytic activity of the mature pernisineco was confirmed using zymography, at a molecular weight of 36 kDa. Enzymatic performances of pernisine evaluated under different temperatures and pHs demonstrate that the optimal enzymatic activity of the recombinant pernisine is ca. 100°C and pH 7.0, respectively. These data demonstrate that codon optimisation is crucial for pernisine overexpression in E. coli. Pernisine is activated by autoproteolytical cleavage of its N-terminal proregion. We have also confirmed that the recombinant pernisine retains the characteristics of native pernisine, as a calcium modulated thermostable serine protease.
COBISS.SI-ID: 4530040