Alena Tomšik - Academia.edu (original) (raw)

Papers by Alena Tomšik

Foods, Jun 20, 2024

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Polymers, Jan 6, 2024

Industrial Crops and Products, Mar 1, 2023

Food Packaging and Shelf Life, Sep 1, 2019

Novel active films of polylactide (PLA) containing extract of Allium ursinum L. (AU), also called... more Novel active films of polylactide (PLA) containing extract of Allium ursinum L. (AU), also called wild garlic, at 10 wt% were succesfully prepared by the electrospinning technology. Electrospinning of the AU-containing PLA solutions yielded fibers in the 1-2 μm range with a beaded-like morphology, suggesting that the AU extract was mainly encapsulated in certain fiber regions. The resultant electrospun mats were then subjected to annealing at 135°C to obtain continuous films of application interest in active packaging. The film cross-sections revealed that the AU extract was incorporated into the PLA matrix in the form of micro-sized droplets. The thermal properties showed that the AU extract addition plasticized the PLA matrix and also lowered its crystallinity degree as it disrupted the ordering of the PLA chains by hindering their folding into the crystalline lattice. Thermal stability analysis indicated that the natural extract positively contributed to a delay in thermal degradation of the biopolymer and it was thermally stable when encapsulated in the PLA film. The AU extract incorporation also produced a mechanical reinforcement on the electrospun PLA films and improved slightly the water barrier performance. Finally, a significant antimicrobial activity of the electrospun PLA films containing the natural extract was achieved against foodborne bacteria.

Sustainable Chemistry and Pharmacy, Jun 1, 2023

International Journal of Biological Macromolecules

International Journal of Morphology

Doxorubicin (DOX) is one of the drugs necessary for the treatment of the 10 most common types of ... more Doxorubicin (DOX) is one of the drugs necessary for the treatment of the 10 most common types of cancer. The leading adverse effect limiting clinical use of DOX is cardiotoxicity. Given that literature data indicate a protective role of carotenoids in doxorubicin-induced toxicity, in our study we compared the cardioprotective effect of a mixture of pumpkin carotenoids and a commercially available antioxidant preparation. Animals were distributed in 8 groups (Control-S; NADES-N; Doxorubicin-Dox; Carotenoids-Car; CardiofortIN-CF; NADES-Doxorubicin-N-Dox; Carotenoids-Doxorubicin-Car-Dox; CardiofortIN-Doxorubicin-CF-Dox). Histological sections were stained with the hematoxylin-eosin (HE) and analyzed for the presence of myocardial damage by doxorubicin damage score (DDS). From the heart tissue homogenate were determined the intensity of lipid peroxidation and specific antioxidative enzyme activity (superoxide dismutase; catalase; glutathione S-transferase; glutathione peroxidase). In Car-DOX and CF-DOX groups, lipid peroxidation is significantly reduced compared to DOX group. Pretreatment of animals with carotenoids and in lesser extent with CardiofortIN led to higher antioxidative enzymes activity, compared to DOX group. Pretreated with carotenoids, only 50 % of animals had some degree of myocardial damage, and no animals had extensive damage. CardiofortIN pretreatment showed less protective effect. Pretreatment with carotenoid extract, reduced DDS significantly, so Car-DOX group has changes equivalent to mild myocardial damage. Although CardiofortIN pretreatment lowered DDS score values, animals still had moderate level of myocardium damage. This in vivo study and its findings indicate that carotenoids extracted from pumpkin may be a promising cardioprotective agent against doxorubicin induced cardiotoxicity, at least in part mediated through inhibition of DOX-induced oxidative stress.

Foods

This study aimed to determine the impact of ancient wheat varieties (emmer, spelt and khorasan) a... more This study aimed to determine the impact of ancient wheat varieties (emmer, spelt and khorasan) and spontaneous sourdough fermentation on the bioaccessibility of total phenolic content (TPC) and the DPPH antioxidant capacity evolution during breadmaking and in vitro digestion. Sourdough and yeast-fermented modern wheat breads were used as controls. After 6 h of fermentation, the total titrable acidity of the sourdough increased from 139 to 167%. The wheat variety, type of fermentation and processing affected TPC, antioxidant activity and bioaccessibility. Antioxidant activity and TPC were reduced by dough mixing, increased after sourdough fermentation and slightly decreased or remained the same after baking. Although wheat flour had the highest TPC, the modeling of TPC kinetic revealed that emmer and spelt sourdough exhibited a higher bound phenolics release rate due to the higher acidity, which contributed to increased phenolics solubility. Although wheat bread, both before and aft...

Sambucu nigra L. belongs to the group of plants recognizable by its strong biological activity wh... more Sambucu nigra L. belongs to the group of plants recognizable by its strong biological activity which was well-known in traditional medicine. However, modern science has confirmed many of its activities such as antimicrobial, antioxidant, immunomodulatory, etc. The biological ability of the plant is closely related with its chemical composition, in the first place with its polyphenolic constituents. The content of individual components in extracts is strongly influenced by isolation technique, as well as the type of solvent. Therefore, the aim of this study was to investigate the influence of modern (microwave-assisted extraction, MAE) and traditional (maceration, MAC) extraction techniques on polyphenol yield in S.nigra extracts, as well as on their biological activity. At the same time, the influence of the two most commonly used solvents (water and ethanol) on the mentioned outputs was also examined. The obtained extracts were analyzed spectrophotometrically in order to determine the content of total phenols and flavonoids, while the content of individual polyphenolic components was measured chromatographically using the LC-MS/MS technique. The biological potential of the obtained extracts was determined by measuring their antioxidant and enzyme-inhibitory activities. The obtained results showed that in all examined extract 15 different components were identified, while the two analyzed compounds were under the LoD. Among the identified components the most dominant was quinic acid as well as rutine. It was noticed that MAE was the more prominent technique for the isolation of target compounds, while ethanol was marked as a solvent with better solvating properties towards to polyphenols in comparison to water. Antioxidant assays showed that all examined extracts were capable to act as free-radical scavenges and antioxidants. By applying in vitro assays the ability of the extracts to inhibit the activity of amylase and acetylcholinesterase was determined, and it was showed that they were much more active towards to amylase (2.18-7.14 mg ACAE/mL) than to acetylcholinesterase (0.09-0.11mg GALAE/mL).

Cilj ove doktorske disertacije je bio odrediti niz tehnoloških postupaka koji bi omogućili iskori... more Cilj ove doktorske disertacije je bio odrediti niz tehnoloških postupaka koji bi omogućili iskorišćenje sremuša u prehrambene i farmaceutske svrhe u svežem ili suvom stanju, kao biljne droge za pripremu različitih formi ekstrakata bogatih bioaktivnim jedinjenjima izolovanih iz njega. List sremuša bere se u vrlo kratkom vremenskom periodu tokom proleća, a nakon branja njegovi listovi vrlo brzo venu i gube svoja senzorna, nutritivna i funkcionalna svojstva, zbog čega je dostupnost ove biljne sirovine vremenski vrlo ograničena. Zbog toga su ispitani uslovi skladištenja svežeg lista sremuša kako bi se sagledala trajnost sremuša za konzumiranje u svežem stanju, ali i mogućnost primene skladištenog sremuša za ekstrakciju bioaktivnih jedinjenja. Za dobijanje osušenog lista sremuša ispitan je uticaj različitih tehnika sušenja (konvektivno i vakuumsko sušenje) i temperature sušenja (40, 50, 60 i 70 °C) na sadržaj bioaktivnih komponenti u osušenom proizvodu. Primenom odgovarajuće tehnike suše...

ACS Sustainable Chemistry & Engineering

Hospital Pharmacology - International Multidisciplinary Journal

Introduction: Carotenoids are liposoluble plant pigments. The most common in the human diet are a... more Introduction: Carotenoids are liposoluble plant pigments. The most common in the human diet are a-carotene, b-carotene, b-cryptoxanthin, lycopene, lutein, and zeaxanthin. Methods: This article provides an overview of the findings on carotenoids to date, their depots in body, recommended daily doses and mechanisms of protective action. We searched PubMed, Google Scholar, SCIndex, Dimension, Scopus and Google for English and Serbian language abstracts, using the searching terms "carotenoids", "provitamin A", "antioxidants", "cardiotoxcity", "prevention" and "NADES". Topic: After being metabolised in intestinal mucosa (with the help of bile acids) and absorbed, carotenoids are mainly stored in the liver and adipose tissue. Major impact on carotenoids bioavailability is the nature of matrix/medium in which they are dissolved. The latest generation of non-toxic "green" solvents, the so-called NADES (natural deep eutect...

Microorganisms

The antimicrobial activity of Allium ursinum aqueous extract prepared using high pressure extract... more The antimicrobial activity of Allium ursinum aqueous extract prepared using high pressure extraction was evaluated. Minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) of A. ursinum extract for six bacterial pathogens were determined using the broth macrodilution method. Although the A. ursinum extract was shown to be effective toward all investigated foodborne bacteria, its antimicrobial activity depended on its concentration and bacterial strain. Listeria monocytogenes was the most sensitive to antimicrobial activity of A. ursinum extract among all tested pathogens. Accordingly, the lowest MIC and MBC of A. ursinum extract were determined for L. monocytogenes (28 and 29 mg/mL). The tested extract showed a similar antimicrobial potential to other examined bacterial strains (Salmonella Enteritidis, Proteus hauseri, Enterococcus faecalis and two strains of Escherichia coli) with MIC and MBC values at concentrations of 29 and 30 mg/mL, respectively. T...

Foods, 2022

Functional food is lately an interesting topic from the new product development perspective; comp... more Functional food is lately an interesting topic from the new product development perspective; complex motivation and expectations of consumers regarding it present a challenge when new products are designed. Co-creation is an interesting alternative to the standard practices by the R & D departments since it directly involves consumers in the various stages of the creation process. This work aims to describe experiences of engaging consumers in different development stages of a functional food product within a project realized at a food research institute. Four consecutive studies were conducted: the first study explored current trends in Serbia regarding the way consumers use functional food and are informed about it; the second study described development of a raspberry seeds extract with antioxidant and anti-proliferative activity confirmed in vitro; the third study tested the same extract in a sample of consumers, validating its usability in food products; and the fourth study de...

The paper presents the synthesis of hydrogels via free-radical polymerization, based on Chitosan ... more The paper presents the synthesis of hydrogels via free-radical polymerization, based on Chitosan (CS) grafted with Acrylic acid (AA), using a two-step procedure. Free-radical polymerization has given strong hydrogels with compact structure, dominant elastic behavior and long linear viscoelastic region. The results of rheological studies have shown that obtained hydrogels have significantly improved mechanical properties in comparison to chitosan hydrogels obtained by other sustainable methods. A step forward in the investigation of the potential application of chitosan hydrogels in wound dressing systems has been made by preparation of the bilayer design by embedding a layer of active compound-loaded alginate beads into the contact surface between two conjoined units of CS/AA hydrogels. Wild garlic (Allium ursinum L.) dried extract was used as an active compound because of its antimicrobial activity and green properties. This system has demonstrated pH-dependent release of extract a...

Antioxidants

Defatted raspberry seeds were used as an alternative source of antioxidants and ellagic acid (EA)... more Defatted raspberry seeds were used as an alternative source of antioxidants and ellagic acid (EA) extracted using Natural deep eutectic solvents (NADES). In the preliminary study, the best NADES combination (citric acid-betaine) and the most influential variables (temperature, time, and NADES/plant ratio) were selected for the further optimization process. All samples were analyzed in terms of total polyphenol, EA content, and antioxidant activity. Two sets of optimal conditions were generated by response surface methodology. The first set (Opt1) was designed for higher conversion of ellagitannins to EA while the latter set (Opt2) for higher EA content/100 g extract. Opt1 and Opt2 had higher values for all investigated responses compared to 80% ethanolic extract but had a lower conversion rate of ellagitannins to EA compared to acidified methanol extract. The third set of parameters (Opt3) selected beyond the initial experimental domain was used to obtain a sample with the highest E...

The Journal of Supercritical Fluids

Abstract Subcritical water extraction (SWE) was employed in order to obtain high valuable extract... more Abstract Subcritical water extraction (SWE) was employed in order to obtain high valuable extracts from wild garlic (Allium ursinum). The influence of temperature (120–200 °C), extraction time (10–30 min) and added acidifier, HCl (0–1.5%) on extraction process was investigated. Analysis of variance was used to determine the fitness of the model and optimal process parameters for SWE, in order to maximize extraction yield, total phenolic compounds and total flavonoids content, and antioxidant activity. The optimal conditions for SWE were determined at temperature of 180.92 °C, extraction time of 10 min, and added acidifier at 1.09%. An insight into the development of Maillard reaction products during SWE was provided through measurement of 5-hydroximethylfurfural(5-HMF) and furfural (F)in all obtained extracts. No influence of 5-HMF and F on antioxidant activity was observed. Using HPLC-DAD, kaempferol derivates were identified as the major phenolic compounds in extract obtained at optimal condition.