Authors:A. Leskó, M. Kállay, B. Nyúl-Pühra, and D. Nyitrai-Sárdy
While keeping wines on the fine lees the composition of nitrogen-containing substances, including the amino acid concentration, changes as a result of the autolysis of yeasts. During the course of former experiments, it was proven that yeasts were able to reduce the polyphenolic composition of wines. As part of the research for the present publication, the change of polyphenolic content in ‘Chardonnay’ wines kept on the lees was analysed. In addition the quantity of tyrosol, required for the forming of simple phenolics, was examined. The results proved that yeasts reduced the quantity of polyphenolics. In addition, due to the increased amino acid concentration, yeasts reduced the quantity of tyrosol that is derived from the amino acid called tyrosine.
Authors:S. Gonda, L. Tóth, P. Parizsa, M. Nyitrai, and G. Vasas
Five species of Plantago genus, namely P. lanceolata, P. major, P. media, P. altissima and P. maritima were screened for iridoid content (CE-MEKC), total caffeoyl phenylethanoid glycoside (CPG) content and antioxidant activity (CUPRAC assay). The five species could be distinguished by TLC pattern analysis in a single run in a system commonly used for quality management of P. lanceolata leaves, as shown by cluster analysis of major bands; with the exception, that P. altissima and P. lanceolata did not show enough pattern difference to be fully separated. P. maritima was shown to have the highest antioxidant capacity (0.42 μmol ascorbic acid equivalent (AAE)/g DW), and the highest level of CPGs (4.29%). P. altissima was shown to be chemically indistinguishable from P. lanceolata with repsect to iridoid content (aucubin 0.55 ± 0.04%, 0.68 ± 0.23%, catalpol 0.66 ± 0.13% and 0.89 ± 0.22%, respectively), CPG content (2.40 ± 0.38% and 2.54 ± 0.56%, respectively) and antioxidant capacity (0.2206 ± 0.0290 and 0.2428 ± 0.0191 μmol AAEAC/g DW). The presented data show the potency of medicinal use of Hungarian wild populations of the studied five species, especially in the case of P. maritima, and that P. altissima can be a potential replacement of P. lanceolata in herbal mixtures.
Authors:A. Leskó, D. Nyitrai-Sárdy, M. Kállay, and I. Balga
The sensory quality of red wines is basically determined by the colour, which depends on the amount and on the evolution of anthocyanins and other phenolic compounds extracting from the berries into the wine during wine-making. The anthocyanin-monomers are responsible for the development of the red colour, and their acylated derivatives provide stability for the colour of the wines. The anthocyanin profile of wines is affected by several factors: the grape variety, the conditions during wine-making, and also the yeast culture used for the fermentation. In our experiments a self-compiled model solution was fermented by spontaneous fermentation, as well as by four commercial yeasts under laboratory conditions. After fermentation total polyphenolics, anthocyanins, anthocyanin monomer profile, colour intensity, hue, and the ratio of polymeric anthocyanins were studied. Our results show that the spontaneous yeast fermentation resulted in a higher anthocyanin concentration in the fermented model solution, but the commercial yeast strains provided a more advantageous colour characteristic compared to the spontaneous fermentation. After the spontaneous fermentation less sediment was left than in the commercial yeast fermented samples.
Authors:B. Nagy, J. Soós, B. Horvath, M. Kállay, B. Nyúl-Pühra, and D. Nyitrai-Sárdy
During the ageing in barrels, the contact with the fine lees triggers several processes in wine. Lees has a reductive effect by absorbing dissolved oxygen and reducing the amount, which will remain in the wine. At present, minimizing the addition of sulphur dioxide is the trend in all viticultural areas. In this study, the effect of various sulphur dioxide levels was monitored in presence of the lees to determine which dose is appropriate to provide the protection of susceptible white wine against oxidation.
Without SO2 protection, the rH and redox potential changed slightly, so the level of dissolved oxygen seemed to be controlled during the ageing period by the lees, though the antioxidant effect of lees in itself was not appropriate to protect the polyphenol content from chemical oxidation, which led to considerable browning. With the addition of a lower amount of SO2 — 40 mg l2, the lees is already able to protect the white wine samples in all aspects.
Authors:Andrea Vig, Réka Dudás, Tünde Kupi, J. Orbán, G. Hild, D. Lőrinczy, and M. Nyitrai
The effect of phalloidin on filaments polymerized from ADP-actin monomers of the heart muscle was investigated with differential
scanning calorimetry. Heart muscle contains α-skeletal and α-cardiac actin isoforms. In the absence of phalloidin the melting
temperature was 55°C for the α-cardiac actin isoform and 58°C for the α-skeletal one when the filaments were generated from
ADP-actin monomers. After the binding of phalloidin the melting temperature was isoform independent (85.5°C). We concluded
that phalloidin stabilized the actin filaments of α-skeletal and α-cardiac actin isoforms to the same extent when they were
polymerized from ADP-actin monomers.
Authors:Eszter Virág, Á. Juhász, R. Kardos, Z. Gazdag, G. Papp, Ágota Pénzes, M. Nyitrai, Cs. Vágvölgyi, and M. Pesti
Interaction of primycin antibiotic with plasma membrane, and its indirect biological effects were investigated in this study. The antifungal activity of primycin against 13 human pathogenic Candida ATCC and CBS reference species and 74 other Candida albicans clinical isolates was investigated with a microdilution technique. No primycin-resistant strain was detected. Direct interaction of primycin with the plasma membrane was demonstrated for the first time by using an ergosterol-producing strain 33erg+ and its ergosterol-less mutant erg-2. In growth inhibition tests, the 33erg+ strain proved to be more sensitive to primycin than its erg-2 mutant, indicating the importance of the plasma membrane composition in primycin-induced processes. The 64 μg ml−1 (56.8 nM) primycin treatment induced an enhanced membrane fluidity and altered plasma membrane dynamics, as measured by steady-state fluorescence anisotropy applying a trimethylammonium-diphenylhexatriene (TMA-DPH) fluorescence polarization probe. The following consequences were detected. The plasma membrane of the cells lost its barrier function, and the efflux of 260-nm-absorbing materials from treated cells of both strains was 1.5–1.8 times more than that for the control. Depending on the primycin concentration, the cells exhibited unipolar budding, pseudohyphae formation, and a rough cell surface visualized by scanning electron microscopy.