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1.
Sustainable extraction of hemp seed and formulation extracts into organogels with analytical profiling of fatty acidssubcritical fluids in food processing
Sara Karlovšek, Taja Žitek Makoter, Teo Makoter, Željko Knez, Maša Knez Marevci, 2025, original scientific article

Abstract: Sustainable extraction methods for natural extracts are crucial for mitigating environmental impact. Strategies that focus on waste reduction and resource efficiency contribute to long-term conservation. Hemp seeds, which were previously treated as waste product, are now valued for their nutrition and functional properties. This study investigated sustainable extraction methods for obtaining natural extracts from hemp seeds, with a focus on reducing environmental impact through efficient resource utilization and waste reduction. The extraction methods compared included supercritical fluid extraction (SFE), Soxhlet extraction (SOX), ultrasound-assisted extraction (UAE), cold maceration (CM), and cold pressing (CP). The contents of antioxidants, total phenols, and fatty acids in the extracts were analyzed via gas chromatography–mass spectrometry (GC–MS). The extracts were subsequently formulated into organogels to evaluate the stability of the fatty acids. The results showed that SFE and CP were the most efficient and environmentally friendly methods, with SFE allowing complete separation of the solvent from the extract. CP was also found to be effective and environmentally friendly. The study confirmed that formulating extracts in organogels effectively inhibited fatty acid oxidation, although a reduction in fatty acid content was observed during gel production. Overall, the formulation of extracts in organogels increased their stability, especially in preventing fatty acid degradation.
Keywords: supercritical fluid extraction, ultrasound extraction, cold pressing method, fatty acids, stability of formulations
Published in DKUM: 15.10.2025; Views: 0; Downloads: 2
.pdf Full text (911,70 KB)

2.
Odgovornost delavca za uporabo orodja ChatGPT pri delu
Matej Makoter Rožmarin, Asja Lešnik, 2025, published scientific conference contribution

Abstract: Umetna inteligenca je čedalje bolj prisotna na vseh področjih, tudi v delovnem okolju. Eno izmed najpogosteje uporabljenih umetnointeligenčnih orodij je orodje ChatGPT, ki ga delavci pogosto uporabljajo za iskanje informacij, kot pomoč pri generiranju besedil in pri analizi podatkov ter celo za avtomatizacijo določenih nalog. Vse to odpira vprašanje odgovornosti v primeru, ko se delavec pri opravljanju dela zanaša na informacije, ki mu jih ponudi ChatGPT, pri čemer zaradi napačnih, nepopolnih ali zavajajočih informacij delodajalcu povzroči škodo.
Keywords: umetna inteligenca, ChatGPT, škoda, delovno pravo, odškodninska odgovornost
Published in DKUM: 02.10.2025; Views: 0; Downloads: 2
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3.
Beneficial effects of castanea sativa wood extract on the human body and possible food and pharmaceutical applications
Taja Žitek Makoter, Mojca Tancer Verboten, Ivan Mirt, Katarina Zupančić, Darija Cör Andrejč, Željko Knez, Maša Knez Marevci, 2024, review article

Abstract: The aim of this review was to investigate the potential use of Castanea sativa wood extract as a food supplement and to evaluate its beneficial properties for human health. The results of the limited amount of studies suggest promising properties, including potential anti-inflammatory effects. The literature indicates that the extract, which is rich in bioactive compounds such as tannins, offers promising therapeutic possibilities for the treatment of conditions associated with chronic inflammation. Consequently, interest in its use in food and pharmaceuticals is growing. Phytochemical studies have reported antioxidant and antimicrobial activities, and anti-inflammatory, anticancer, hypolipidemic, hypoglycemic, and neuroprotective activities. A suitable extraction method and solvent is crucial for the isolation of bioactive compounds, being green extraction technologies outstanding for the industrial recovery of chestnut wood’s bioactive compounds. Nevertheless, it is important to emphasize the importance of adhering to regulatory guidelines and obtaining the necessary approvals from regulatory authorities to ensure product safety and compliance. The regulation of herbal medicinal products with proven efficacy and traditional herbal medicinal products is well defined, monitored by authorized bodies, and subject to strict control measures. It is noteworthy that medicinal products are subject to stringent quality testing to ensure safety and efficacy in use, whereas there are no comparable regulatory standards and specific labeling requirements for dietary supplements. When using herbal products, compliance with established standards in health research is essential.
Keywords: Castanea sativa, wood extracts, tannins, antioxidat activity, anti-inflammatory activity, antimicrobial activity
Published in DKUM: 30.07.2025; Views: 0; Downloads: 5
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4.
Synergistic effect of supercritical and ultrasound-assisted ginger (Zingiber officinale Roscoe) extracts
Taja Žitek Makoter, Nika Kučuk, Vesna Postružnik, Maja Leitgeb, Željko Knez, Mateja Primožič, Maša Knez Marevci, 2022, original scientific article

Abstract: Proper processing of natural material is crucial to obtain an extract with high content of biologically active components. Dried, grinded ginger roots were extracted by ultrasonic method and supercritical extraction with CO2 . The aim of the study was to determine if a mixture of the two types of extracts attained by different methods and solvents exhibits better bioavailability than each extract itself. Therefore, both extracts were analytically evaluated and then mixed in a ratio of 1:1. The supercritical extract (SCG extract) and the mixed extract (mixG extract) had high antioxidant activity (78% and 73%) and total phenols (827 mg/g ext. and 1455 mg/g ext.), which is also consistent with the levels of gingerol (303 mg/g ext. and 271 g/g ext.) and shogaol (111 mg/g ext. and 100 g/g ext.) in the extracts. In comparison to both pure extracts higher levels of total phenols were found in the extract mixG. This could be the reason for the significant inhibition of melanoma cells and antimicrobial potential (against Staphylococcus aureus, Escherichia coli, and Candida albicans). The combination of the extracts resulted in a significant increase in the inhibition of selected microbial and melanoma cells WM-266-4 compared to the control. Cell viability decreased below 60% when mixG extract was applied. Antimicrobial activity has been confirmed.
Keywords: ginger, supercritical fluid extraction, ultrasound-assisted extraction, antimicrobial activity
Published in DKUM: 09.05.2025; Views: 0; Downloads: 6
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5.
Optimisation of the green process of industrial hemp - preparation and its extract characterisation
Taja Žitek Makoter, Petra Kotnik, Teo Makoter, Vesna Postružnik, Željko Knez, Maša Knez Marevci, 2022, original scientific article

Abstract: Natural medicines and products are becoming increasingly important in the pharmaceutical and food industries. The most important step in obtaining a natural remedy is the processing of the natural material. This study offers the separation of the industrial hemp plant into fractions by mechanical treatment, which has a significant impact on the selectivity of the obtained fractions. This study also offers a solution to reduce waste by fractionating industrial hemp, focusing on the fraction with the highest cannabinoid content (49.5% of CBD). The study confirmed the anticancer potential of the extract, which prevents further division of WM-266-4 melanoma cells at a concentration of 10−3 mg/mL. However, application of the extract (c = 10−3 mg/mL) to normal human epidermal melanocytes proved to be insignificant, as the metabolic activity of the cells was the same as in the control cell group.
Keywords: supercritical fluid extraction, ultrasonic extraction, melanoma cells, extraction, WM-266-4
Published in DKUM: 09.05.2025; Views: 0; Downloads: 6
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6.
Comparison of conventional and supercritical isolation methods from bee pollen and their effects on the concentrations of bioactive compounds
Taja Žitek Makoter, Vesna Postružnik, Anastasia Kyriakoudi, Elli Pantazi, Natasa Kalogiouri, Ioannis Mourtzinos, Željko Knez, Maša Knez Marevci, 2025, original scientific article

Abstract: The present work represents a profound investigation of material pretreatment, comparison of different isolation methods (conventional and supercritical), and characterization of phenolic compounds and amino acids from bee pollen. The determination of amino acids was carried out after developing a novel hydrophilic interaction chromatography combined with quadrupole time-of-flight tandem mass spectrometric method (HILIC-QTOF-MS/MS) with limits of detection over the range 1 mg/kg -5 mg/kg and recoveries over the range 87.6% - 97.1%. The optimal conditions for the isolation of amino acids are in the range of temperatures between 25°C to 55°C and at pressures between 300 bar and 350 bar. It can be concluded that the extraction temperature and the pressure affect antioxidant activity. The favored conditions are lower temperatures and higher pressures.
Keywords: bee pollen, in vitro antioxidant activity, HILIC-LC-QTOF-MS.MS, amino acids, WM-266-4 cells
Published in DKUM: 20.03.2025; Views: 0; Downloads: 3
.pdf Full text (1,27 MB)

7.
Optimization of the supercritical extraction and decarboxylation process of industrial hemp
Taja Žitek Makoter, Petra Kotnik, Teo Makoter, Željko Knez, Maša Knez Marevci, 2025, original scientific article

Abstract: Cannabinoids are the main active ingredients of Cannabis sativa L., obtained by a suitable extraction method and decarboxylation, in which the acid forms of the cannabinoids are converted into active forms. Supercritical CO2 extraction method and decarboxylation process were optimized for 7 cannabinoids (CBD, CBDA, THC, THCA, CBGA, CBN and CBC). The optimal extraction conditions for all cannabinoids were determined at a temperature of 60 °C and a pressure of 300 bar to 550 bar. At higher temperatures and reaction times, a significant depletion of neutral cannabinoids was observed. The optimal conditions of the decarboxylation process varied depending on the component. For the CBD component, which could be measured in the highest concentrations (560 mg/g), the optimal conditions were 140 °C and 10 min. The study can be an important model for predicting the behavior of cannabinoids under certain parameters.
Keywords: supercritical fluids, extraction, cannabinoids, decarboxilation, Cannabis sativa I
Published in DKUM: 08.01.2025; Views: 0; Downloads: 12
.pdf Full text (10,15 MB)

8.
Moderna zgodovina razvoja pravnega sistema na slovenskem ozemlju : magistrsko delo
Tadej Makoter Rožmarin, 2024, master's thesis

Abstract: V magistrski nalogi je v ospredju predvsem zgodovinski vidik razvoja celotnega slovenskega pravnega sistema, tako sodnega, kot tudi zakonodajnega. Gre za razpon zgodovinskih obdobij od Avstrijske monarhije, Avstro-Ogrske in vseh kasnejših oblik povezovanja balkanskih narodov, torej Jugoslavije, torej predvsem druga polovica 19. stoletja in 20 stoletje. Raziskoval bom ustavne ureditve, kako so vplivale na zakonodajo in ureditev, tako civilnega, kot kazenskega, družinskega, upravnega in volilnega, tako javnega kot zasebnega prava. Prav tako se bom osredotočil na pomembnejše posameznike, ki so s svojimi revolucionarnimi idejami in modernejšimi vidiki pomembno oblikovali tok razvoja prava in demokracije. Dotaknil se bom tudi političnih smeri in kako se je glede na ta prepričanja prilagajala zakonodaja in menjavalo vodstvo države. Pomembni vidik je tudi vpliv na razvoj in uporabo slovenskega jezika, ki ga bom preko dokumentov in arhivskih besedil v magistrski nalogi izpostavil in predstavil. Gre za enega od temeljev oblikovanja narodov in narodnega zavedanja ter oblikovanja uporabe prava v slovenščini in začetka slovenskih pravnih postopkov in sodstva. Med drugim bom izpostavil tudi pomembnejša ozemlja, na katera je bilo razdeljeno slovensko ozemlje, med različnimi obdobji in vladavino, kajti razvoj velikokrat ni bil enoten na vseh ozemljih, predvsem zaradi različnih vplivov sosednjih dežel in ljudstev ter razlikah v ideologiji prava. Geografsko gledano se bom najbolj osredotočil ravno na področje današnje Slovenije in okolico, predvsem Avstrijo, nekatere dele Italije in seveda bivše države SFR Jugoslavije, ker se je v moderni dobi ravno v tem času in teh vladavinah slovensko pravo najbolj razvijalo in na koncu koncev postalo samostojen in neodvisen pravni sistem.
Keywords: Ustava, monarhija, kraljevina, republika, pravni sistem, Slovenski jezik, zakon, komunizem, socializem, kapitalizem, temeljna načela, parlament, skupščina.
Published in DKUM: 20.12.2024; Views: 0; Downloads: 98
.pdf Full text (1,53 MB)

9.
Priprava organogelov z ekstrakti kurkume z optimalnim profilom sproščanja
Nastja Šiler, 2024, master's thesis

Abstract: Namen magistrskega dela je izolacija in določitev biološko aktivnih komponent (kurkuminoidov) v ekstraktih kurkume, formulacija ekstrahiranih učinkovin s ciljem čim večje vsebnosti kurkumina in preverjanje protimikrobnega potenciala dobljenih ekstraktov in formulacij. Izvedli smo dve različni ekstrakcijski metodi. Pri ultrazvočni ekstrakciji smo kot topilo uporabili etanol, medtem ko smo superkritično ekstrakcijo izvedli s superkritičnim ogljikovim dioksidom. Nastalim ekstraktom smo določili antioksidativno aktivnost z metodo DPPH· ter vsebnosti totalnih fenolov, proantocianidinov, karotenoidov in vitamina C. Ekstrakte smo nato formulirali v organogele in enkapsulate. Vsebnost kurkumina smo določili v ekstraktih in organogelih, njegovo topnost v superkritičnem ogljikovem dioksidu pa smo preverili z uporabo visokotlačne celice pri različnih tlakih. Na koncu je sledila še analiza protimikrobnega potenciala, s katero smo pripravljenim ekstraktom in formulacijam določili minimalno inhibitorno koncentracijo. Iz rezultatov je razvidno, da je najvišji ekstrakcijski izkoristek pri ultrazvočni ekstrakciji (5,77 %). Prav tako smo temu ekstraktu, v primerjavi s superkritičnim, spektrofotometrično določili višji % inhibicije (41,93 %) in višje vsebnosti totalnih fenolov (2,06 mg GA/g materiala), proantocianidinov (0,6 mg PAC/g materiala) ter vitamina C (0,20 mg vitamina C/g materiala). Tudi vsebnosti kurkumina so višje v ultrazvočnem ekstraktu. Ultrazvočni ekstrakt in njegove formulacije imajo nižjo minimalno inhibitorno koncentracijo kot superkritični ekstrakt in njegove formulacije. Najnižnjo minimalno inhibitorno koncentracijo (0,47 mg/mL) smo določili ultrazvočenmu ekstraktu pri uporabi bakterije Staphylococcus aureus in glive Candida albicans. S tem smo dodatno potrdili višje vsebnosti kurkumina v ultrazvočnem ekstraktu in tudi to, da kurkumin deluje protimikrobno.
Keywords: kurkuma, kurkumin, ekstrakcija, organogeli, enkapsulacija, antimikrobni potencial
Published in DKUM: 10.09.2024; Views: 44; Downloads: 81
.pdf Full text (3,29 MB)

10.
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