1. Določanje topnosti in tališč derivatov imidazola v superkritičnem co2Neva Kovač, 2025, magistrsko delo Opis: Magistrsko delo prikazuje študijo obnašanja treh derivatov imidazola (imidazola, benzimidazola in 2-metilimidazola) v superkritičnem ogljikovem dioksidu. Namen raziskave je določiti topnosti in tališča derivatov pri različnih tlakih in temperaturah ter oceniti vpliv strukturnih razlik med derivati na njihove fizikalno-kemijske lastnosti v superkritičnem mediju.
Topnosti imidazola in benzimidazola so bile določene s statično-analitično metodo pri temperaturah 40 °C in 60 °C ter tlakih do 800 bar. Rezultati kažejo, da topnost obeh spojin z naraščajočim tlakom sprva narašča in doseže maksimum med 400 bar in 500 bar, nato pa se ponovno zmanjšuje. Pri imidazolu je topnost v celotnem območju tlakov višja pri 60 °C, kar potrjuje pozitiven vpliv temperature, medtem ko je pri benzimidazolu topnost višja pri 40 °C, kar nakazuje nasproten temperaturni učinek. Imidazol doseže največjo topnost 0,025 g/g CO2, benzimidazol pa le 0,0058 g/g CO2, kar kaže na izrazit vpliv molekulske strukture na raztapljanje v superkritičnem ogljikovem dioksidu.
Tališča vseh treh derivatov so bila določena z modificirano kapilarno metodo. V vseh primerih se temperatura tališča z začetnim povečevanjem tlaka znižuje, nato pa pri višjih tlakih ponovno narašča. Najizrazitejši padec temperature taljenja je bil opažen pri 2-metilimidazolu (32,5 °C).
Rezultati prispevajo k boljšemu razumevanju faznega obnašanja in medmolekulskih interakcij heterocikličnih spojin v superkritičnem ogljikovem dioksidu, kar je pomembno za načrtovanje procesov superkritične ekstrakcije, kristalizacije in sinteze materialov.
Ključne besede: imidazol, benzimidazol, 2-metilimidazol, superkritični ogljikov dioksid, topnost, tališče
Objavljeno v DKUM: 24.11.2025; Ogledov: 0; Prenosov: 6
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2. Beneficial effects of castanea sativa wood extract on the human body and possible food and pharmaceutical applicationsTaja Žitek Makoter, Mojca Tancer Verboten, Ivan Mirt, Katarina Zupančić, Darija Cör Andrejč, Željko Knez, Maša Knez Marevci, 2024, pregledni znanstveni članek Opis: 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.
Ključne besede: Castanea sativa, wood extracts, tannins, antioxidat activity, anti-inflammatory activity, antimicrobial activity
Objavljeno v DKUM: 30.07.2025; Ogledov: 0; Prenosov: 7
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3. Izolacija biološko aktivnih komponent iz Betonica officinalis : diplomsko delo univerzitetnega študijskega programa I. stopnjeUrška Dovnik, 2024, diplomsko delo Opis: Betonika (Betonica officinalis) ima zaradi svoje zdravilnosti široko paleto uporabe v zgodovini. Odločili smo se izolirati biološko aktivne komponente iz posušenih delov betonike in jih okarakterizirati. Pri tem smo uporabili dve različni ekstrakcijski metodi (maceracijo in UZ ekstrakcija) in topili etanol in voda ter njihove mešanice. Ugotavljali smo kako različne ekstrakcijske metode in topila vplivajo na izolacijo biološko aktivnih komponent iz betonike. Najvišje izkoristke ekstrakcij smo dosegli z vročo maceracijo (približno 14 %). Pridobljenim ekstraktom smo nato določili vsebnost totalnih fenolov, proantocianidinov in antioksidativni potencial. Totalne fenole smo določali s pomočjo Follin-Ciocalteu reagenta. Kot standardno raztopino smo uporabili galno kislino. Rezultate smo podali v mg GA na g ekstrakta oz. materiala. Vsebnost proantocianidinov v ekstraktih smo določili z uporabo Porter-Hrstich-Chantovo metode. Pri tem smo kot standard uporabili cianidin. Rezultate smo podali v mg PAC na g ekstrakta oz. materiala. Nenazadnje smo s pomočjo DPPH testa določili antioksidativni potencial izoliranih spojin. Rezultati analiz so pokazali, da betonika vsebuje od 1-13,4 mg GA/g materiala. Prisotnost proantocianidinov je med 0,09 in 0,77 mg PAC/g materiala. Test DPPH je pokazal, da antioksidativna aktivnost ekstraktov betonike niha med 16,7 % in 31%.
Ključne besede: ekstrakcija, betonika, totalni fenoli, proantocianidini, antioksidativnost
Objavljeno v DKUM: 02.12.2024; Ogledov: 0; Prenosov: 65
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4. 20th European Meeting on Supercritical Fluids : Book of Abstracts2024 Opis: The 20th European Meeting on Supercritical Fluids (EMSF 2024) was hosted by the Faculty of Chemistry and Chemical Engineering of the University of Maribor from 26 May to 29 May 2024 in Maribor, Slovenia. The EMSF 2024 was a joint event of the International Society for the Advancement of Supercritical Fluids (ISASF) and the European Federation of Chemical Engineering (EFCE) Working Party on High Pressure Technology (WP HPT) Event No. 807. This symposium provided an excellent opportunity for engineers, chemists, physicists, food technologists, and biologists to meet and discuss new ideas, review ongoing challenges, present potential solutions, and identify future issues related to high pressure technologies and supercritical fluids. The aim of the meeting was to deepen connections between researchers, establish new contacts, and promote synergies and partnerships between researchers. The symposium presented the latest advances in high-pressure process technologies that can contribute to the further development of the field.
Ključne besede: supercritical fluids, fundamental data, novel materials, industrial applications, research and development
Objavljeno v DKUM: 24.07.2024; Ogledov: 161; Prenosov: 42
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5. Evaluation of ethanol-induced chitosan aerogels with human osteoblast cellsMilica Pantić, Uroš Maver, Jan Rožanc, Boštjan Vihar, Darija Cör Andrejč, Željko Knez, Zoran Novak, 2023, izvirni znanstveni članek Ključne besede: chitosan, aerogels, supercritical drying, bone tissue engineering, osteoblasts
Objavljeno v DKUM: 06.05.2024; Ogledov: 209; Prenosov: 43
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6. Izolacija maščobnih kislin iz bučnih semen vrste cucurbita pepo : magistrsko deloNika Hočevar, 2024, magistrsko delo Opis: V magistrskem delu smo izvedli različne metode ekstrakcij bučnih semen, raziskali biološki pomen maščobnih kislin, preučevali izolacijo le-teh iz bučnih semen vrste Cucurbita pepo. Bučna semena že dolgo veljajo za prehransko bogato in zdravo sestavino, ki vsebujejo esencialne hranilne snovi, med njimi tudi pomembne maščobne kisline.
Za pridobivanje ekstrakta bučnih semen smo uporabili konvencionalne ekstrakcije, s topilom petrol eter in superkrične ekstrakcije z uporabo ogljikovega dioksida pri različnih pogojih. Izvedli smo saponifikacijo ter določili vsebnost maščobnih kislin z metodo GC-MS. Ugotavljamo, da ekstrakcija s Soxhletovim aparatom prinese največji izkoristek pri konvencionalnih ekstrakcijah, medtem ko je superkrična ekstrakcija najvišji izkoristek prinesla pri tlaku 400 bar in temperaturi 60 °C. Analiza maščobnih kislin je razkrila, da je najbolj zastopana oleinska kislina, sledita ji linolna in palmitinska kislina. Pri konstantni temperaturi 60 °C smo z višanjem tlaka pridobili večjo vsebnost oleinske in linolne kisline. Vsebnost maščobnih kislin v ekstraktih je bila primerljiva, ne glede na uporabljeno metodo. Zaključek poudarja pomembnost esencialnih maščobnih kislin, še posebej linolne ter oleinske kisline v bučnih semenih ter odpira poti novim možnostim v prehrambeni in medicinski industriji. Raziskava prispeva k razvoju znanja na področju izolacije in uporabe ekstraktov bučnih semen ter poziva k nadaljnjim raziskavam za izboljšanje prehranskih dopolnil in splošnega zdravja ljudi.
Ključne besede: bučna semena, superkritična ekstrakcija, maščobne kisline, saponifikacija, GC-MS
Objavljeno v DKUM: 06.02.2024; Ogledov: 379; Prenosov: 64
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7. Vpliv procesnih parametrov na kakovost in obstojnost ekstrakta ameriškega slamnika (Echinacea purpurea) : diplomsko deloKatja Fingušt, 2023, diplomsko delo Opis: V diplomskem delu smo raziskovali vpliv procesnih parametrov na kakovost in obstojnost ekstrakta ameriškega slamnika. Želeli smo pridobiti stabilne ekstrakte ter izolirati čim višje vsebnosti polifenolov in polisaharidov. Najprej smo izvedli sejalno analizo, s katero smo določili mediansko zrno, najpogosteje zastopano zrno in koeficient zrnatosti, ter ugotovili, da je bila zrnatost neenakomerna. V laboratoriju smo izvajali vročo in hladno maceracijo ter ultrazvočno ekstrakcijo. Uporabljali smo pet različnih topil: destilirano vodo, absolutni etanol ter mešanice etanol:voda (70:30), etanol:voda (50:50) ter etil acetat:voda (70:30). Ko smo izvedli vse ekstrakcije, smo pričeli z analiznim delom, kjer smo s spektrofotometričnimi metodami določili vsebnosti totalnih fenolov in proantocianidinov ter antioksidativno aktivnost ekstraktov in ugotovili, da je imel ekstrakt, pridobljen z vročo maceracijo in topilom etanol:voda (70:30), najvišji izkoristek, najvišjo vsebnost totalnih fenolov in najvišjo antioksidativno aktivnost. Najnižji izkoristek pa je imel ekstrakt, ki smo ga pridobili z ultrazvočno ekstrakcijo, kjer smo kot topilo uporabili absolutni etanol. Prav tako je imel ta ekstrakt tudi najnižjo vsebnost totalnih fenolov in proantocianidinov. Večinoma so ekstrakti pokazali visoke vsebnosti fenolnih spojin. Etanolni ekstrakti so pokazali višje vsebnosti fenolnih spojin, prisotnost vode pa je povečala ekstrakcijo proantocianidinov, kar je potrdilo naši hipotezi. Kot predvidevano smo najvišje izkoristke dobili pri vroči maceraciji. Kasneje smo izvedli mikroenkapsulacijo in pridobljenim formulatom določili antioksidativno delovanje ter ugotovili, da je bila učinkovitost precej nizka.
Ključne besede: ameriški slamnik, ekstrakcija, totalni fenoli, antioksidanti, proantocianidini, sejalna analiza
Objavljeno v DKUM: 14.09.2023; Ogledov: 573; Prenosov: 0
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8. Green techniques for preparation of red beetroot extracts with enhanced biological potentialDragana Borjan, Vanja Šeregelj, Darija Cör Andrejč, Lato Pezo, Vesna Tumbas Šaponjac, Željko Knez, Jelena J. Vulić, Maša Knez Marevci, 2022, izvirni znanstveni članek Opis: Red beetroot is well known for its high proportion of betalains, with great potential as functional food ingredients due to their health-promoting properties. The objective of this study was to investigate the influence of processing techniques such as Soxhlet, cold, ultrasound and supercritical fluid extraction on the betalains content and its antioxidant, anti-inflammatory and antihyperglycemic activities. Whilst Soxhlet extraction with water has provided the highest yield, the highest content of total phenolics was found in an extract prepared using Soxhlet extraction with 50% ethanol. Amongst eight phenolic compounds detected in the extracts, protocatechuic acid was the most abundant. The concentrations of total phenolics ranged from 12.09 mg/g (ultrasound extraction with 30% methanol) to 18.60 mg/g (Soxhlet extraction with 50% ethanol). The highest anti-inflammatory activity was observed for cold extraction with 50% methanol extract. The high radical scavenging activity of supercritical fluid extracts could be a consequence of nonphenolic compounds. The chemometrics approach was further used to analyse the results to find the “greenest” method for further possible application in the processing of beetroot in the food and/or pharmaceutical industry. According to the standard score, the best extraction method was determined to be Soxhlet extraction with 50% ethanol.
Ključne besede: red beetroot, supercritical fluid extraction, antioxidant activity, anti-inflammatory activity, antihyperglycemic activity, chemometric approach
Objavljeno v DKUM: 18.08.2023; Ogledov: 436; Prenosov: 132
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9. Antioxidant, antibacterial, antitumor, antifungal, antiviral, anti-inflammatory, and nevro-protective activity of Ganoderma lucidum : an overviewDarija Cör Andrejč, Željko Knez, Maša Knez Marevci, 2022, pregledni znanstveni članek Opis: Ganoderma lucidum is a very medicinal mushroom that has been utilized in Oriental medicine for many years. It has a wide range of pharmacological and therapeutic properties, and has been used for many years as a health promoter. It contains various biologically active compounds that improve the immune system and have antioxidant, antitumor, anti-inflammatory, antifungal, and antimicrobial properties. Active compounds include triterpenoids and polysaccharides, as well as proteins, lipids, phenolics, sterols, etc. In the following review, we summarize briefly their biological activities, such as antioxidant, anti-bacterial, anti-fungal, antitumor, anti-viral, and anti-inflammatory activity. Although Ganoderma has a number of medicinal effects that have been confirmed by the in vitro and in vivo studies summarised in this review, there are some limitations. Clinical trials face mainly a lack of pure constituents. Accurate identification of the compounds obtained is also problematic. In addition, most of the included studies were small, and there were concerns about the methodological quality of each study. Studies have shown that Ganoderma has valuable potential for the prevention and treatment of cancer. In any case, G. lucidum cannot be used as first-line therapy for cancer.
Ključne besede: Ganoderma lucidum, bioactive function, active compounds, polysaccharides, triterpenoids
Objavljeno v DKUM: 16.08.2023; Ogledov: 324; Prenosov: 64
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10. The effect of drying methods and extraction techniques on oleuropein content in olive leavesDarija Cör Andrejč, Bojan Butinar, Željko Knez, Kaja Tomažič, Maša Knez Marevci, 2022, izvirni znanstveni članek Opis: Increased demand for olive oil has caused higher quantities of byproducts in olive processing, such as olive leaves, olive skins, and vegetation water. It is well known that olive leaves contain several phenolic compounds, including secoiridoids. Oleuropein is the major secoiridoid in olive leaves. Oleuropein has been found to exhibit antioxidative, antimicrobial, antiviral, and antiatherogenic activities. We studied the effect of extraction techniques and drying methods on oleuropein content in olive leaves of Istrska belica and Lecino cultivar. Three different procedures of drying were used: at room temperature, at 105 °C, and freeze drying. Ethanol-modified supercritical extraction with carbon dioxide, conventional methanol extraction, and ultrasonic extraction with deep eutectic solvent were performed. Antioxidant activity was determined, as well as methanolic and supercritical extracts. The presence of olive polyphenols was confirmed by the HPLC method.
Ključne besede: olive leaves, drying, different extraction techniques, oleuropein
Objavljeno v DKUM: 10.08.2023; Ogledov: 352; Prenosov: 421
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