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Article ; Online: Diverse Mechanisms of Antimicrobial Activities of Lactoferrins, Lactoferricins, and Other Lactoferrin-Derived Peptides

Špela Gruden / Nataša Poklar Ulrih

International Journal of Molecular Sciences, Vol 22, Iss 11264, p

2021 Volume 11264

Abstract: Lactoferrins are an iron-binding glycoprotein that have important protective roles in the mammalian body through their numerous functions, which include antimicrobial, antitumor, anti-inflammatory, immunomodulatory, and antioxidant activities. Among ... ...

Abstract	Lactoferrins are an iron-binding glycoprotein that have important protective roles in the mammalian body through their numerous functions, which include antimicrobial, antitumor, anti-inflammatory, immunomodulatory, and antioxidant activities. Among these, their antimicrobial activity has been the most studied, although the mechanism behind antimicrobial activities remains to be elucidated. Thirty years ago, the first lactoferrin-derived peptide was isolated and showed higher antimicrobial activity than the native lactoferrin lactoferricin. Since then, numerous studies have investigated the antimicrobial potencies of lactoferrins, lactoferricins, and other lactoferrin-derived peptides to better understand their antimicrobial activities at the molecular level. This review defines the current antibacterial, antiviral, antifungal, and antiparasitic activities of lactoferrins, lactoferricins, and lactoferrin-derived peptides. The primary focus is on their different mechanisms of activity against bacteria, viruses, fungi, and parasites. The role of their structure, amino-acid composition, conformation, charge, hydrophobicity, and other factors that affect their mechanisms of antimicrobial activity are also reviewed.
Keywords	lactoferrin ; lactoferricin ; peptides ; antimicrobial activity ; mechanisms of action ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
Subject code	571
Language	English
Publishing date	2021-10-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Basic Methods for Preparation of Liposomes and Studying Their Interactions with Different Compounds, with the Emphasis on Polyphenols

Luka Šturm / Nataša Poklar Ulrih

International Journal of Molecular Sciences, Vol 22, Iss 6547, p

2021 Volume 6547

Abstract: Studying the interactions between lipid membranes and various bioactive molecules (e.g., polyphenols) is important for determining the effects they can have on the functionality of lipid bilayers. This knowledge allows us to use the chosen compounds as ... ...

Abstract	Studying the interactions between lipid membranes and various bioactive molecules (e.g., polyphenols) is important for determining the effects they can have on the functionality of lipid bilayers. This knowledge allows us to use the chosen compounds as potential inhibitors of bacterial and cancer cells, for elimination of viruses, or simply for keeping our healthy cells in good condition. As studying those effect can be exceedingly difficult on living cells, model lipid membranes, such as liposomes, can be used instead. Liposomal bilayer systems represent the most basic platform for studying those interactions, as they are simple, quite easy to prepare and relatively stable. They are especially useful for investigating the effects of bioactive compounds on the structure and kinetics of simple lipid membranes. In this review, we have described the most basic methods available for preparation of liposomes, as well as the essential techniques for studying the effects of bioactive compounds on those liposomes. Additionally, we have provided details for an easy laboratory implementation of some of the described methods, which should prove useful especially to those relatively new on this research field.
Keywords	model lipid bilayers ; bioactive compounds ; membrane fluidity ; membrane kinetics ; essential methods for liposome/vesicle preparation ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
Subject code	540
Language	English
Publishing date	2021-06-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Thermally Induced Transitions of d(G 4 T 4 G 3 ) Quadruplexes Can Be Described as Kinetically Driven Processes

Iztok Prislan / Tomaz Urbic / Natasa Poklar Ulrih

Life, Vol 12, Iss 825, p

2022 Volume 825

Abstract: DNA sequences that are rich in guanines and can form four-stranded structures are called G-quadruplexes. Due to the growing evidence that they may play an important role in several key biological processes, the G-quadruplexes have captured the interest ... ...

Abstract	DNA sequences that are rich in guanines and can form four-stranded structures are called G-quadruplexes. Due to the growing evidence that they may play an important role in several key biological processes, the G-quadruplexes have captured the interest of several researchers. G-quadruplexes may form in the presence of different metal cations as polymorphic structures formed in kinetically governed processes. Here we investigate a complex polymorphism of d(G 4 T 4 G 3 ) quadruplexes at different K + concentrations. We show that population size of different d(G 4 T 4 G 3 ) quadruplex conformations can be manipulated by cooling rate and/or K + concentration. We use a kinetic model to describe data obtained from DSC, CD and UV spectroscopy and PAGE experiments. Our model is able to describe the observed thermally induced conformational transitions of d(G 4 T 4 G 3 ) quadruplexes at different K + concentrations.
Keywords	G-quadruplexes ; potassium ; calorimetry ; polymorphism ; kinetics ; folding ; Science ; Q
Subject code	290
Language	English
Publishing date	2022-06-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Effects of Hydrophobic Gold Nanoparticles on Structure and Fluidity of SOPC Lipid Membranes

Poornima Budime Santhosh / Tihomir Tenev / Luka Šturm / Nataša Poklar Ulrih / Julia Genova

International Journal of Molecular Sciences, Vol 24, Iss 10226, p

2023 Volume 10226

Abstract: Gold nanoparticles (AuNPs) are promising candidates in various biomedical applications such as sensors, imaging, and cancer therapy. Understanding the influence of AuNPs on lipid membranes is important to assure their safety in the biological environment ...

Abstract	Gold nanoparticles (AuNPs) are promising candidates in various biomedical applications such as sensors, imaging, and cancer therapy. Understanding the influence of AuNPs on lipid membranes is important to assure their safety in the biological environment and to improve their scope in nanomedicine. In this regard, the present study aimed to analyze the effects of different concentrations (0.5, 1, and 2 wt.%) of dodecanethiol functionalized hydrophobic AuNPs on the structure and fluidity of zwitterionic 1-stearoyl-2-oleoyl- sn -glycerol-3-phosphocholine (SOPC) lipid bilayer membranes using Fourier-transform infrared (FTIR) spectroscopy and fluorescent spectroscopy. The size of AuNPs was found to be 2.2 ± 1.1 nm using transmission electron microscopy. FTIR results have shown that the AuNPs induced a slight shift in methylene stretching bands, while the band positions of carbonyl and phosphate group stretching were unaffected. Temperature-dependent fluorescent anisotropy measurements showed that the incorporation of AuNPs up to 2 wt.% did not affect the lipid order in membranes. Overall, these results indicate that the hydrophobic AuNPs in the studied concentration did not cause any significant alterations in the structure and membrane fluidity, which suggests the suitability of these particles to form liposome–AuNP hybrids for diverse biomedical applications including drug delivery and therapy.
Keywords	gold nanoparticles ; phospholipids ; biomedical applications ; membrane fluidity ; infrared spectroscopy ; Biology (General) ; QH301-705.5 ; Chemistry ; QD1-999
Subject code	540
Language	English
Publishing date	2023-06-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Effect of heat treatment on phenolic composition and radical scavenging activity of olive leaf extract at different pH conditions: a spectroscopic and kinetic study

Gonzalez‐Ortega, Rodrigo / Di Mattia, Carla Daniela / Pittia, Paola / Natasa, Poklar Ulrih

Journal of the Science of Food and Agriculture. 2023 Mar. 15, v. 103, no. 4 p.2047-2056

2023

Abstract: BACKGROUND: The present study focused on the effect of isothermal treatment (5–90 °C) and pH (2.0–6.0) of aqueous olive leaf phenolic extract solutions on the kinetics of degradation of single and total phenolic compounds and radical scavenging activity, ...

Abstract	BACKGROUND: The present study focused on the effect of isothermal treatment (5–90 °C) and pH (2.0–6.0) of aqueous olive leaf phenolic extract solutions on the kinetics of degradation of single and total phenolic compounds and radical scavenging activity, with the objective of predicting and optimizing the thermal treatments in foods enriched with olive leaf extracts. RESULTS: The major compound, oleuropein, showed higher degradation at low pH 2.0 and temperature‐dependent reaction rates, which fitted well a first‐order kinetic model, with an estimated activation energy of 98.03 ± 0.08 kJ mol⁻¹. Oleuropein hydrolysis resulted in a zero‐order increase in hydroxytyrosol concentration at same pH (Eₐ = 71.59 ± 1.5 kJ mol⁻¹), whereas a 100‐fold slower degradation rate was observed at higher pH. Verbascoside was only degraded at pH 6.0, also following first‐order kinetics. These changes in oleuropein and hydroxytyrosol concentrations led to significant changes in fluorescence maximum intensities centered around 315 and 360 nm and in the 425–500 nm spectral zone for samples at pH 6.0, which could be associated with verbacoside degradation. Conversely, analysis of total phenolic content and 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) radical scavenging activity showed little changes, indicating a rather constant overall reducing capacity of the resulting pool of compounds after thermal treatments. CONCLUSION: The present study can contribute to the knowledge related to oleuropein and phenolic fraction degradation as a result of matrix (pH) and processing. The kinetic parameters obtained could be applied for predicting and optimizing the thermal treatments in foods and drinks enriched with olive leaf extracts. © 2022 Society of Chemical Industry.
Keywords	activation energy ; agriculture ; fluorescence ; heat treatment ; hydrolysis ; kinetics ; leaf extracts ; leaves ; oleuropein ; olives ; pH ; spectroscopy ; verbascoside
Language	English
Dates of publication	2023-0315
Size	p. 2047-2056.
Publishing place	John Wiley & Sons, Ltd.
Document type	Article ; Online
Note	JOURNAL ARTICLE
ZDB-ID	184116-6
ISSN	1097-0010 ; 0022-5142
ISSN (online)	1097-0010
ISSN	0022-5142
DOI	10.1002/jsfa.12371
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: An Overview of Crucial Dietary Substances and Their Modes of Action for Prevention of Neurodegenerative Diseases

Lea Pogačnik / Ajda Ota / Nataša Poklar Ulrih

Cells, Vol 9, Iss 3, p

2020 Volume 576

Abstract: Neurodegenerative diseases, namely Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis, Huntington’s disease, and multiple sclerosis are becoming one of the main health concerns due to the increasing aging of the world’s ... ...

Abstract	Neurodegenerative diseases, namely Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis, Huntington’s disease, and multiple sclerosis are becoming one of the main health concerns due to the increasing aging of the world’s population. These diseases often share the same biological mechanisms, including neuroinflammation, oxidative stress, and/or protein fibrillation. Recently, there have been many studies published pointing out the possibilities to reduce and postpone the clinical manifestation of these deadly diseases through lifelong consumption of some crucial dietary substances, among which phytochemicals (e.g., polyphenols) and endogenous substances (e.g., acetyl-L-carnitine, coenzyme Q10, n-3 poysaturated fatty acids) showed the most promising results. Another important issue that has been pointed out recently is the availability of these substances to the central nervous system, where they have to be present in high enough concentrations in order to exhibit their neuroprotective properties. As so, such the aim of this review is to summarize the recent findings regarding neuroprotective substances, their mechanisms of action, as well as to point out therapeutic considerations, including their bioavailability and safety for humans.
Keywords	dietary phytochemicals ; endogenous substances ; mitochondrial dysfunction ; neurodegenerative diseases ; neuroinflammation ; oxidative stress ; protein fibrillation ; Biology (General) ; QH301-705.5
Subject code	610
Language	English
Publishing date	2020-02-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Thermal and Rheological Properties of Gluten-Free, Starch-Based Model Systems Modified by Hydrocolloids

Polona Megusar / David Stopar / Natasa Poklar Ulrih / Iztok Dogsa / Iztok Prislan

Polymers, Vol 14, Iss 16, p

2022 Volume 3242

Abstract: Obtaining good-quality gluten-free products represents a technological challenge; thus, it is important to understand how and why the addition of hydrocolloids influences the properties of starch-based products. To obtain insight into the physicochemical ...

Abstract	Obtaining good-quality gluten-free products represents a technological challenge; thus, it is important to understand how and why the addition of hydrocolloids influences the properties of starch-based products. To obtain insight into the physicochemical changes imparted by hydrocolloids on gluten-free dough, we prepared several suspensions with different corn starch/potato starch/hydroxpropyl methyl cellulose/xanthan gum/water ratios. Properties of the prepared samples were determined by differential scanning calorimetry and rheometry. Samples with different corn/potato starch ratios exhibited different thermal properties. Xanthan gum and HPMC (hydroxypropyl methyl cellulose) exhibited a strong influence on the rheological properties of the mixtures since they increased the viscosity and elasticity. HPMC and xanthan gum increased the temperature of starch gelatinization, as well as they increased the viscoelasticity of the starch model system. Although the two hydrocolloids affected the properties of starch mixtures in the same direction, the magnitude of their effects was different. Our results indicate that water availability, which plays a crucial role in the starch gelatinization process, could be modified by adding hydrocolloids such as, hydroxypropyl methyl cellulose and xanthan gum. By adding comparatively small amounts of the studied hydrocolloids to starch, one can achieve similar thermo-mechanical effects by the addition of gluten. Understanding these effects of hydrocolloids could contribute to the development of better quality gluten-free bread with optimized ingredient content.
Keywords	hydrocolloids ; gluten-free ; differential scanning calorimetry ; rheology ; Organic chemistry ; QD241-441
Subject code	660
Language	English
Publishing date	2022-08-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Peptides derived from food sources: Antioxidative activities and interactions with model lipid membranes

Gluvić, Ana / Nataša Poklar Ulrih

Food chemistry. 2019 July 30, v. 287

2019

Abstract: We studied seven known peptides derived from different food proteins, and one hydrophobic peptide derived through in-silico hydrolysis. We investigated their antioxidative, antimicrobial and haemolytic activities and their interactions with model lipid ... ...

Abstract	We studied seven known peptides derived from different food proteins, and one hydrophobic peptide derived through in-silico hydrolysis. We investigated their antioxidative, antimicrobial and haemolytic activities and their interactions with model lipid membranes. Our data reveal that peptides with histidines are the most effective for protection against lipid peroxidation, as: P#3 (VHHA) > P#5 (LHALLL) > P#7 (LLPHH). The most potent peptide towards metal-induced oxidation was P#2 (LQKW), which contained an aromatic tryptophan at its C-terminus. The peptides with negative hydrophobicity, as P#1 (PEL) and P#2 (LQKW), were the most potent according to DPPH radical scavenging. The most potent peptide towards superoxide radicals was the four-amino-acid chain with aromatic amino acids, P#2 (LQKW). The peptides studied did not show haemolytic or antimicrobial activities, except P#4 (AAGGV) against Listeria monocytogenes. These peptides did not interact with model lipid membranes, except P#8, which was designed to span lipid bilayers.
Keywords	2,2-diphenyl-1-picrylhydrazyl ; Listeria monocytogenes ; antimicrobial properties ; antioxidant activity ; dietary protein ; histidine ; hydrolysis ; hydrophobicity ; lipid bilayers ; lipid peroxidation ; lipids ; models ; oxidation ; peptides ; superoxide anion ; tryptophan
Language	English
Dates of publication	2019-0730
Size	p. 324-332.
Publishing place	Elsevier Ltd
Document type	Article
ZDB-ID	243123-3
ISSN	1873-7072 ; 0308-8146
ISSN (online)	1873-7072
ISSN	0308-8146
DOI	10.1016/j.foodchem.2019.02.092
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Effect of hydrolysis degree with Alcalase on antioxidant and antigenic properties of whey and colostrum protein hydrolysates

Tatsiana M. Halavach / Vladimir P. Kurchenko / Ekaterina I. Tarun / Alexey V. Yantsevich / Veronika V. Shchur / Vasili G. Tsygankow / Aleksey D. Lodygin / Ivan A. Evdokimov / Natasa Poklar Ulrih

Journal of Agriculture and Food Research, Vol 15, Iss , Pp 100975- (2024)

2024

Abstract: Enzymatic hydrolysis of dairy proteins is aimed to increase their nutritional value and reduce their allergenic properties. It is relevant to study the effects of enzymatic hydrolysis with highly active endopeptidase alсalase on the bioactivity of the ... ...

Abstract	Enzymatic hydrolysis of dairy proteins is aimed to increase their nutritional value and reduce their allergenic properties. It is relevant to study the effects of enzymatic hydrolysis with highly active endopeptidase alсalase on the bioactivity of the whey and colostrum protein components. Dairy hydrolysates with various degree of Alcalase treatment were obtained in the present study. A comparative analysis of cleaved dairy proteins and their peptide fractions with a 5 and 10 kDa cutoff was performed. The protein and peptide composition of hydrolysates was determined using various techniques. The bioactivity of hydrolyzed whey and colostrum samples were estimated. The antioxidant activity of hydrolyzed and fractionated (5 kDa cutoff) whey samples increased by 5.91/6.62-fold and that of colostrum by 14.22/7.24-fold in fluorimetric/spectrophotometric assay, respectively. A significant decrease in the antigenic potential of milk peptides was observed with increasing degree of hydrolysis and subsequent ultrafiltration. Thus, bioactive dairy protein hydrolysates were obtained, which are applicable as a component of specialized foods with proven hypoallergenic properties and high antioxidant activity.
Keywords	Whey ; Colostrum ; Enzymatic hydrolysis ; Alсalase ; Hydrolysis degree ; Peptide profile ; Agriculture (General) ; S1-972 ; Nutrition. Foods and food supply ; TX341-641
Subject code	540
Language	English
Publishing date	2024-03-01T00:00:00Z
Publisher	Elsevier
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Effect of heat treatment on phenolic composition and radical scavenging activity of olive leaf extract at different pH conditions: a spectroscopic and kinetic study.

Gonzalez-Ortega, Rodrigo / Di Mattia, Carla Daniela / Pittia, Paola / Natasa, Poklar Ulrih

Journal of the science of food and agriculture

2022 Volume 103, Issue 4, Page(s) 2047–2056

Abstract: Background: The present study focused on the effect of isothermal treatment (5-90 °C) and pH (2.0-6.0) of aqueous olive leaf phenolic extract solutions on the kinetics of degradation of single and total phenolic compounds and radical scavenging activity, ...

Abstract	Background: The present study focused on the effect of isothermal treatment (5-90 °C) and pH (2.0-6.0) of aqueous olive leaf phenolic extract solutions on the kinetics of degradation of single and total phenolic compounds and radical scavenging activity, with the objective of predicting and optimizing the thermal treatments in foods enriched with olive leaf extracts. Results: The major compound, oleuropein, showed higher degradation at low pH 2.0 and temperature-dependent reaction rates, which fitted well a first-order kinetic model, with an estimated activation energy of 98.03 ± 0.08 kJ mol Conclusion: The present study can contribute to the knowledge related to oleuropein and phenolic fraction degradation as a result of matrix (pH) and processing. The kinetic parameters obtained could be applied for predicting and optimizing the thermal treatments in foods and drinks enriched with olive leaf extracts. © 2022 Society of Chemical Industry.
MeSH term(s)	Antioxidants/chemistry ; Hot Temperature ; Iridoids/chemistry ; Phenols/chemistry ; Olea/chemistry ; Plant Extracts/chemistry ; Hydrogen-Ion Concentration ; Plant Leaves
Chemical Substances	olive leaf extract (MJ95C3OH47) ; Antioxidants ; oleuropein (2O4553545L) ; 3,4-dihydroxyphenylethanol (10597-60-1) ; Iridoids ; Phenols ; Plant Extracts
Language	English
Publishing date	2022-12-12
Publishing country	England
Document type	Journal Article
ZDB-ID	184116-6
ISSN	1097-0010 ; 0022-5142
ISSN (online)	1097-0010
ISSN	0022-5142
DOI	10.1002/jsfa.12371
Database	MEDical Literature Analysis and Retrieval System OnLINE

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