https://repository-scidap.cvtisr.sk//jspui/handle/123456789/9 Sat, 18 Dec 2021 21:27:42 GMT 2021-12-18T21:27:42Z https://repository-scidap.cvtisr.sk//jspui/handle/123456789/25 Title: A Switch between Antioxidant and Prooxidant Properties of the Phenolic Compounds Myricetin, Morin, 3′,4′-Dihydroxyflavone, Taxifolin and 4-Hydroxy-Coumarin in the Presence of Copper(II) Ions: A Spectroscopic, Absorption Titration and DNA Damage Study Authors: Jomová, Klaudia; Hudecová, Lenka; Lauro, Peter; Šimunková, Miriama; Alwasel, Saleh H.; Alhazza, Ibrahim M.; Valko, Marián Abstract: The beneficial effects of polyphenols, predominantly in the context of oxidative stress-related diseases such as cancer, cardiovascular diseases and neurological conditions including Alzheimer’s and Parkinson’s diseases, have been documented by a number of papers and reviews. The antioxidant/prooxidant properties of phenolic compounds are related mainly to the number and positions of hydroxyl groups and to their redox metal (Cu, Fe) chelating capacity. In this work we studied structurally distinct phenolic molecules such as myricetin, morin, 3′,4′-dihydroxy-flavone, taxifolin and 4-hydroxycoumarin, either alone or as interacting with Cu2+ ions. EPR and UV-Vis spectroscopy confirmed that the effective binding of cupric ions to phenolic compounds requires the presence of the 3-OH and 4-CO groups on the flavonoid C ring and unsaturated C2-C3 bond of the C-ring, which permits through-conjugation with the B-ring. An ABTS assay revealed that radical scavenging activities of phenolic compounds are related to their number of hydroxyl groups, planarity of the molecular skeleton, extent of delocalization and they decrease in the order: myricetin > morin > 3′,4′-dihydroxyflavone ~ 4-hydroxy coumarin > taxifolin. Absorption titrations indicate that copper ions can modulate the DNA binding affinity of flavonoids via the formation of their Cu-chelates. Gel electrophoresis measurements indicated that the protective effect of the phenolic compounds decreases in the order: 3′,4′-dihydroxyflavone > 4-OH coumarin > morin > taxifolin ~ myricetin. This can be explained by the fact that myricetin, taxifolin and morin form stable Cu(II) complexes capable of causing DNA damage via interaction with DNA and ROS formation via the Fenton reaction. Application of ROS scavengers revealed the formation of singlet oxygen, superoxide and hydroxyl radicals and their concerted synergistic effect on the DNA. The overall results suggest that the most pronounced DNA damage has been observed for flavonoids containing higher number of hydroxyl groups (including 3-OH group of the C ring), such as myricetin (six hydroxyl groups), morin and taxifolin (five hydroxyl groups) in the presence of Cu(II) ions. The proposed mechanism of action by which Cu(II) complexes of myricetin, morin and taxifolin interact with DNA predispose these substances to act as potential anticancer agents. The anticancer activity of phenolic compounds can be explained by their moderate prooxidant properties, which can boost ROS formation and kill cancer cells. Alternatively, slight prooxidant properties may activate antioxidant systems, including antioxidant enzymes and low molecular antioxidants such as glutathione and thus act as preventive anticancer agents. View Full-Text Fri, 01 Nov 2019 00:00:00 GMT https://repository-scidap.cvtisr.sk//jspui/handle/123456789/25 2019-11-01T00:00:00Z https://repository-scidap.cvtisr.sk//jspui/handle/123456789/24 Title: Scalable Preparation of Enantioenriched (S)-5-methylhept-2-en-4-one. Synthesis and Aroma Properties of Achiral Analogues Thereof Authors: Puchľová, Eva; Dendys, Michal; Špánik, Ivan; Szolcsányi, Peter Abstract: (S)-5-Methylhept-2-en-4-one is a key flavour compound in hazelnuts. We have performed its chiral-pool-based chemoenzymatic synthesis with 39% overall yield (73% ee). The four-step aldol-based sequence avoids the use of highly reactive and/or toxic reagents, does not require anhydrous conditions and uses only distillation as the purification method. Thus, such methodology represents a green and scalable alternative to only two stereoselective approaches towards this natural product known so far. In addition, we have designed and prepared a set of new (di)enones as achiral synthetic analogues of the title compound. The results of their sensory analyses clearly show that relatively minor structural changes of the natural molecule significantly alter its olfactory properties. Thus, simple (poly)methylation completely changes the original hazelnut aroma of (S)-5-methylhept-2-en-4-one and shifts the odour of its analogues to eucalyptus, menthol, camphor, and sweet aroma. View Full-Text Sun, 01 Dec 2019 00:00:00 GMT https://repository-scidap.cvtisr.sk//jspui/handle/123456789/24 2019-12-01T00:00:00Z https://repository-scidap.cvtisr.sk//jspui/handle/123456789/23 Title: Syn Flood Attack Detection and Type Distinguishing Mechanism Based on Counting Bloom Filter Authors: Halagan, Tomáš; Kováčik, Tomáš; Trúchly, Peter; Binder, Andrej Abstract: Presented work focuses onto proposal, implementation and evaluation of the new method for detection and type identification of SYN flood (DoS) attacks. The method allows distinguishing type of detected SYN flood attacks – random, subnet or fixed. Based on Counting Bloom filter, the attack detection and identification algorithm is proposed, implemented and evaluated in KaTaLyzer network traffic monitoring tool. Proof of correctness of the approach for TCP SYN flood attack detection and type identification is provided – both in practical and theoretical manners. In practice, new module for KaTaLyzer is implemented and TCP attacks are detected, identified and network administrator is notified about them in real-time. Sun, 01 Nov 2015 00:00:00 GMT https://repository-scidap.cvtisr.sk//jspui/handle/123456789/23 2015-11-01T00:00:00Z https://repository-scidap.cvtisr.sk//jspui/handle/123456789/22 Title: Liveable Open Public Space - From Flaneur to Cyborg Authors: Djukic, Aleksandra; Vlastos, Thanos; Joklová, Viera Abstract: Open public spaces have always been key elements of the city. Now they are also crucial for mixed reality. It is the main carrier of urban life, place for socialization, where users rest, have fun and talk. Moreover, “Seeing others and being seen” is a condition of socialization. Intensity of life in public spaces provides qualities like safety, comfort and attractiveness. Furthermore, open public spaces represent a spatial framework for meetings and multileveled interactions, and should include virtual flows, stimulating merging of physical and digital reality. Aim of the chapter is to present a critical analysis of public open spaces, aspects of their social role and liveability. It will also suggest how new technologies, in a mixed reality world, may enhance design approaches and upgrade the relationship between a user and his surroundings. New technologies are necessary for obtaining physical/digital spaces, becoming playable and liveable which will encourage walking, cycling, standing and interacting. Hence, they will attract more citizens and visitors, assure a healthy environment, quality of life and sociability. Public space, acting as an open book of the history of the city and of its future, should play a new role, being a place of reference for the flaneur/cyborg citizen personal and social life. The key result is a framework for understanding the particular importance of cyberparks in contemporary urban life in order to better adapt technologies in the modern urban life needs. Fri, 01 Mar 2019 00:00:00 GMT https://repository-scidap.cvtisr.sk//jspui/handle/123456789/22 2019-03-01T00:00:00Z