1. Supercritical fluid and conventional extractions of high value-added compounds from pomegranate peels waste: production, quantification and antimicrobial activity of bioactive constituentsKaja Kupnik, Maja Leitgeb, Mateja Primožič, Vesna Postružnik, Petra Kotnik, Nika Kučuk, Željko Knez, Maša Knez Marevci, 2022, izvirni znanstveni članek Opis: This study is focused on different extractions (Cold Maceration (CM), Ultrasonic Extraction
(UE), Soxhlet Extraction (SE) and Supercritical Fluid Extraction (SFE)) of bioactive compounds from
pomegranate (Punica Granatum L.) fruit peels using methanol, ethanol, and acetone as solvents in
conventional extractions and changing operating pressure (10, 15, 20, 25 MPa) in SFE, respectively.
The extraction yields, total phenols (TP) and proanthocyanidins (PAC) contents, and antioxidant
activity of different extracts are revealed. TP and PAC recovered by extracts ranged from 24.22 to
42.92 mg gallic acid equivalents (GAE)/g and 2.01 to 5.82 mg PAC/g, respectively. The antioxidant
activity of extracts ranged from 84.70% to 94.35%. The phenolic compound identification and
quantification in selective extracts was done using the LC-MS/MS method. The contents of different
flavonoids and phenolic acids have been determined. SFE extract, obtained at 20 MPa, contained
the highest content (11,561.84 µg/g) of analyzed total polyphenols, with predominant ellagic acid
(7492.53 µg/g). For the first time, Microbial Growth Inhibition Rates (MGIRs) were determined at
five different concentrations of pomegranate SFE extract against seven microorganisms. Minimal
Inhibitory Concentration (MIC90) was determined as 2.7 mg/mL of SFE pomegranate peel extract in
the case of five different Gram-negative and Gram-positive bacteria.
Ključne besede: antimicrobial activity, antioxidants, bioactive compounds, extraction, LC-MS/MS, phenolics, phytochemistry, pomegranate, Punica Granatum L., secondary metabolites
Objavljeno v DKUM: 24.03.2025; Ogledov: 0; Prenosov: 1
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2. Nanodelci hitozana kot potencialni protimikrobni premazZdenka Peršin Fratnik, Uroš Maver, Metod Kolar, Olivera Šauperl, Lidija Fras Zemljič, Boštjan Vihar, 2024, izvirni znanstveni članek Opis: Namen študije je bil ugotoviti protimikrobno učinkovitost hitozanskih nanodelcev v primerjavi s hitozansko raztopino in sled temu njihovo učinkovito rabo na medicinskih tekstilnih materialih.
Ključne besede: chitosan, nanoparticles, antimicrobial activity, coatings, medical textile materials
Objavljeno v DKUM: 07.01.2025; Ogledov: 0; Prenosov: 23
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3. Antimicrobial activity of amino-modified cellulose nanofibrils decorated with silver nanoparticlesVesna Lazić, Jovan Nedeljković, Vanja Kokol, 2024, izvirni znanstveni članek Opis: Silver nanoparticles (Ag NPs) conjugated with amino-functionalized cellulose nanofibrils (NH2−CNFs) were in situ-prepared by reducing silver ions with free amino groups from NH2−CNFs. The spectroscopy and transmission electron microscopy measurements confirmed the presence of non-agglomerated nanometer-in-size Ag NPs within micrometer-large NH2−CNFs of high (20 wt.-%) content. Although the consumption of amino groups during the formation of Ag NPs lowers the ζ-potential and surface charge of prepared inorganic–organic hybrids (from +31.3 to +19.9 mV and from 2.4 to 1.0 mmol/g at pH 7, respectively), their values are sufficiently positive to ensure electrostatic interaction with negatively charged cell walls of pathogens in acidic and slightly (up to pH ~8.5) alkaline solutions. The antimicrobial activity of hybrid microparticles against various pathogens (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans) is comparable with pristine NH2−CNFs. However, a long-timescale use of hybrids ensures the slow and controlled release of Ag+ ions to surrounding media (less than 1.0 wt.-% for one month).
Ključne besede: amino-modified cellulose nanofibrils, silver nanoparticles, hybrid microparticles, zeta-potential, antimicrobial activity
Objavljeno v DKUM: 09.12.2024; Ogledov: 0; Prenosov: 6
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4. Enzymatic, Antioxidant, and Antimicrobial Activities of Bioactive Compounds from Avocado (Persea americana L.) SeedsKaja Kupnik, Mateja Primožič, Vanja Kokol, Željko Knez, Maja Leitgeb, 2023, izvirni znanstveni članek Ključne besede: avocado seed, Persea Americana, HPLC, phenolic compounds, enzymatic activity, phytochemistry, antioxidant, antimicrobial activity
Objavljeno v DKUM: 10.04.2024; Ogledov: 351; Prenosov: 344
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5. Arnica Montana L. supercritical extraction optimization for antibiotic and anticancer activityTaja Žitek Makoter, Vesna Postružnik, Željko Knez, Andrej Golle, Barbara Dariš, Maša Knez Marevci, 2022, izvirni znanstveni članek Ključne besede: mountain arnica, natural extract, gactive ingredients, antimicrobial activity, anticarcinogenic activity
Objavljeno v DKUM: 05.04.2024; Ogledov: 169; Prenosov: 5
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6. Extending the protection ability and life cycle of medical masks through the washing processJulija Volmajer Valh, Tanja Pušić, Mirjana Čurlin, Ana Knežević, 2023, izvirni znanstveni članek Opis: The reuse of decontaminated disposable medical face masks can contribute to reducing the environmental burden of discarded masks. This research is focused on the effect of household and laboratory washing at 50 °C on the quality and functionality of the nonwoven structure of polypropylene medical masks by varying the washing procedure, bath composition, disinfectant agent, and number of washing cycles as a basis for reusability. The barrier properties of the medical mask were analyzed before and after the first and fifth washing cycle indirectly by measuring the contact angle of the liquid droplets with the front and back surface of the mask, further by measuring air permeability and determining antimicrobial resistance. Additional analysis included FTIR, pH of the material surface and aqueous extract, as well as the determination of residual substances—surfactants—in the aqueous extract of washed versus unwashed medical masks, while their aesthetic aspect was examined by measuring their spectral characteristics. The results showed that household washing had a stronger impact on the change of some functional properties, primarily air permeability, than laboratory washing. The addition of the disinfectant agent, didecyldimethylammonium chloride, contributes to the protective ability and supports the idea that washing of medical masks under controlled conditions can preserve barrier properties and enable reusability.
Ključne besede: medical masks, washing, detergent, didecyldimethylammonium chloride, air permeability, antimicrobial activity, residuals
Objavljeno v DKUM: 15.03.2024; Ogledov: 333; Prenosov: 28
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7. Functionalisation of silicone by drug-embedded chitosan nanoparticles for potential applications in otorhinolaryngologyUrban Ajdnik, Lidija Fras Zemljič, Matej Bračič, Uroš Maver, Olivija Plohl, Janez Rebol, 2019, izvirni znanstveni članek Ključne besede: silicone, tympanostomy tube, chitosan, nanoparticles, drug delivery, antimicrobial activity
Objavljeno v DKUM: 22.03.2019; Ogledov: 1460; Prenosov: 6 |
8. Effect of peptides' binding on the antimicrobial activity and biocompatibility of protein-based substrates Maja Kaisersberger Vincek, 2017, doktorska disertacija Opis: This work reveals the effect of coupling approach (chemical by using carbodiimide chemistry and grafting-to vs. grafting-from synthesis routes, and enzymatic by using transglutaminase) of a hydrophilic ε-poly-L-lysine (εPL) and an amphiphilic oligo-acyl-lysyl (OAK) derivative (K-7α12-OH) to wool fibers and gelatine (GEL) macromolecules, respectively, and substrates antibacterial activity against Gram-negative E. coli and Gram-positive S. aureus bacteria after 1–24 h of exposure, as well as their cytotoxicity. Different spectroscopic (ultraviolet-visible, infrared, fluorescence and electron paramagnetic resonance) and separation techniques (size-exclusion chromatography and capillary zone electrophoresis) as well as zeta potential and potentiometric titration analysis, were performed to confirm the covalent coupling of εPL/OAK, and to determine the amount and orientation of its immobilisation.
The highest and kinetically the fastest level of bacterial reduction was achieved with wool/GEL functionalised with εPL/OAK by chemical grafting-to approach. This effect correlated with both the highest grafting yield and conformationally the highly-flexible (brush-like) orientation linkage of εPL/OAK, implicating on the highest amount of accessible amino groups interacting with bacterial membrane. However, OAK`s amphipathic structure, the cationic charge and the hydrophobic moieties, resulted to relatively high reduction of S. aureus for grafting-from and the enzymatic coupling approaches using OAK-functionalised GEL.
The εPL/OAK-functionalised GEL did not induce toxicity in human osteoblast cells, even at ~25-fold higher concentration than bacterial minimum inhibitory (MIC) concentration of εPL/OAK, supporting their potential usage in biomedical applications.
It was also shown that non-ionic surfactant adsorbs strongly onto the wool surface during the process of washing, thereby blocking the functional sites of immobilized εPL and decreases its antibacterial efficiency.
Ključne besede: wool, gelatine, antimicrobial peptides, ε-poly-L-lysine, oligo-acyl-lysyl, grafting chemistry, grafting approach, peptide orientation, antibacterial activity, cytotoxicity
Objavljeno v DKUM: 17.08.2017; Ogledov: 1931; Prenosov: 178
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9. Viscose functionalisation with a combination of chitosan/BTCA using microwavesOlivera Šauperl, Julija Volmajer Valh, 2013, izvirni znanstveni članek Opis: Improved hygiene and health care standards have a great impact on the development of hygiene and health care products. For this purpose, viscose is a very popular substrate. One of the most promising anti-microbial compounds of modern times is chitosan. The anti-microbial action of this polysaccharide depends on the amino group amount, which is crucial for ensuring the effectiveness of anti-microbial treated material. In textile finishing, 1,2,3,4-buthanetetracarboxylic acid (BTCA) is usually used as a non-formaldehyde crease-resistant reagent. But, on the other hand, the negatively charged carboxyl groups of BTCA can be explored as additional binding sites for positively-charged protonated amino groups of chitosan. When using microwaves, polar materials (e.g. chitosan) orient and reorient themselves according to the direction of the electro-magnetic field, which means that chitosan chain-bending may have taken place during the drying with microwaves. This could result in a higher specific surface of the chitosan and, consequently, in a higher proportion of available amino groups. It is concluded that the combination chitosan/BTCA supported by microwaves drying represents an ideal combination to increase the proportion of available amino groups.
Ključne besede: viskoza, protimikrobna zaščita, viscose, chitosan/BTCA, microwawes, Acid Orange VII, methylene blue, antimicrobial activity
Objavljeno v DKUM: 10.07.2015; Ogledov: 1636; Prenosov: 48
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