Materials Science and Applied Chemistry

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Authors: Ilva Nakurte, Kaspars Jekabsons, Elina Zandberga, Arturs Abols, Aija Line, Ruta Muceniece
Abstract: The detection and profiling of disease-specific extracellular vesicles (EVs) from body fluids has been challenging research area during recent years. However, the question – can EVs surface proteins be exploited as a credible tool for early cancer diagnosis – is still not answered. Objective of the current study was to find out whether hypoxia induces differences in protein profiles of EVs released from hypoxic human colorectal cancer cells SW480 (EVHyp) and EVs released from these cells grown in normoxic conditions – EVNorm. Obtained results show differences in EVs surface protein samples. Some protein fragments were found only or mostly in EVHyp surface protein samples. Finding of one or two such EVHyp protein fragments allows us to suggest that deciphered EVHyp surface proteins might be indices of hypoxia-induced proteome changes and might serve as a hint to find a cancer specific protein.
Authors: Diana Dzabijeva, Anete Boroduske, Anna Ramata-Stunda, Natalja Mazarova, Vizma Nikolajeva, Martins Boroduskis, Ilva Nakurte
Abstract: The present study provides an assessment of extracts of six medicinal plants for their applicability in cosmetic formulations aimed at anti-UV protection and anti-acne treatment. Ethanol extracts of Chelidonium majus L., Myrtus communis L., Hamamelis virginiana L., Juniperus communis L., Alchemilla vulgaris and Ilex paraguariensis are analysed for the phytochemical content, antimicrobial activity, antiradical activity and antiradical kinetics. The phytochemical composition of the plants is investigated by LC-MS analysis and the most active antioxidants in plant extracts are determined by online HPLC-DPPH assay. The kinetic parameters of the antiradical reaction are determined both for the studied plants and chlorogenic acid applying the mathematical treatment of the experimental kinetic data.The study shows that I. paraguariensis ethanolic extract possesses the highest potential in anti-UV and anti-aging cosmetology applications, while M. communis and J. communis reveal excellent antibacterial properties and high potential in anti-acne treatment.
Authors: Valda Valkovska, Agnese Osīte, Lauma Buša, Vizma Nikolajeva
Abstract: Synthetic hydroxyapatite (HAp) has weak antibacterial and mechanical properties. The antibacterial activity of HAp can be enhanced by strontium cation substitution and incorporation of peroxide ion via hydrothermal processing at 100 °C and 150 °C temperature using 50% H2O2 solution. The starting reagents and products of HAp processing were analyzed by thermal conversion elemental analyser – isotopic ratio mass spectrometer in order to determine the δ18O values. Using different host materials it could be possible to determine differences of δ18O values between untreated and hydrothermally treated HAp samples. The enhanced antibacterial properties of processed HAp samples were investigated using Pseudomonas aeruginosa and Staphylococcus aureus. Hydrothermal processing by H2O2 solutions provides additional antibacterial activity and peroxide content of hydrothermally treated samples affect δ18O values.
Authors: Vilnis Peipiņš, Krista Suta, Māris Turks
Abstract: Azetidine derivatives are interesting scaffolds in terms of medicinal chemistry. They can be regarded as structural homologs of aziridines. Herein we report synthetic approach to the novel N-protected 2-triazolyl azetidines which are structurally similar to our previously described aziridine derivatives with matrix metalloproteinase-2 inhihbitory activities. The synthetic rout includes ring closing of ethyl 2,4-dibromobutanoate, selective reduction of ester to aldehyde and transformation of the latter to terminal alkyne by Ohira-Bestmann reagent. 2-Ethynyl azetidines as key intermediates were transformed into triazole derivatives by Cu(I) catalyzed azide-alkyne 1,3-dipolar cycloaddition reaction.
Authors: Kārlis Greitāns, Daina Rībena, Māris Turks
Abstract: 7-Azido-3,6,6-trimethyl-1-(pyridin-2-yl)-1,5,6,7-tetrahydro-4H-indazol-4-one undergoes copper (I)-catalyzed 1,3-dipolar cycloaddition reactions with terminal alkynes and provides the corresponding 7-(1H-1,2,3-triazol-1-yl)-derivatives with excellent yields. Reduction of keto group at C(4) gives an access to diastereoisomeric mixture of alcohols. The latter provide acetamides in the Ritter reaction with acetonitrile upon treatment in acidic media. The developed synthetic sequence offers an easy entry into 4,7-difunctionalized tetrahydroindazoles which are interesting in terms of medicinal chemistry.
Authors: Inese Mieriņa, Laura Jakaite, Sabine Kristone, Laura Adere, Mara Jure
Abstract: This paper is devoted to the studies of total polyphenol content and antiradical activity of peppermint, chamomile and lavender grown in local backyard gardens of Latvia. Different solvents (96, 70 and 40% ethanol) and extraction methods (maceration at room temperature at dark or under day-light irradiation, as well as reflux) were tested. All extracts were analyzed for total polyphenol content (Folin–Ciocalteu method), as well as for antiradical activity (DPPH and GO assays). It was found out that local peppermint and chamomile is as good source of polyphenols as those plants grown in southern countries; however, the total polyphenol content of lavender is lower than that mentioned in literature. The highest polyphenol content for all plant materials was achieved, when 70% ethanol was used for extraction. Peppermint extracts were found as most powerful free radical scavengers among all tested plant materials. 96% Ethanol extract of peppermint and chamomile demonstrated the highest antiradical activity, while 70% ethanol was the most suitable for preparation of lavender extract with optimal free radical scavenging activity.
Authors: Tatjana Gerasimova, Vitālijs Rjabovs, Māris Turks
Abstract: Novel derivatives of fluoroquinolone antibiotic ciprofloxacin were synthesized. The modifications of both the N- and C-termini were focused on introduction of functionalized linkers that can be used for covalent attachment to natural or synthetic polymers with appropriate functional groups.
Authors: Darta Ubele, Liene Pluduma, Karlis Agris Gross, Arturs Viksna
Abstract: Thermal spraying is commercially used to produce hydroxyapatite coatings, but the high temperature depletes hydroxyl ions in the structure. To return hydroxyapatite to its original state, it is necessary to restore the hydroxyl ion content in the structure. In this work, the effect of hydrothermal treatment on the hydroxyl ions was investigated in hydroxyapatite powder and thermally sprayed hydroxyapatite coatings. Samples were hydrothermally treated at 200 °C for 24 h and 48 h. Chemical phases were determined by X-ray diffraction, functional groups and hydroxyl ion concentration was examined by Fourier transform infra-red spectroscopy. Results showed that hydrothermal processing of hydroxyapatite coatings at 200 °C for 48 hours produced the greatest increase in the hydroxyl ion concentration by 29%.
Authors: Liene Pluduma, Karlis Agris Gross, Christian Rey, Arnolds Ubelis, Astrida Berzina
Abstract: The amount and alignment of hydroxyl ions influence the bioactivity of hydroxyapatite. Hydroxyl ions in hydroxyapatite are the most mobile and upon heating are the first to leave the lattice to form oxyhydroxyapatite. This work describes a method for producing hydroxyapatite with different amounts of hydroxyl ions, and reports on the changes in Fourier transform infrared absorption at increasing level of dehydroxylation. Detailed analysis of spectra in the 500 – 700 cm-1 range showed a peak shift for the hydroxyl ion absorption line at 632 cm-1 to 637 cm-1 and an increase in the wavenumber for the phosphate line at 575 cm-1.

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