Papers by Cristina Hlevca
Open Chemistry, 2017
This work aimed to study the potential effects of four Arctii folium extracts, 5 mg gallic [GAE] ... more This work aimed to study the potential effects of four Arctii folium extracts, 5 mg gallic [GAE] acid equivalents per 1 mL sample, on six antibiotics (Ampicillin/AM, Tetracycline/TE, Ciprofloxacin/CIP, Sulfamethoxazole-Trimethoprim/SXT, Chloramphenicol/C and Gentamicin/CN) tested on four Gram-positive (Staphylococcus aureus ATCC 6538, Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, and Staphylococcus epidermidis ATCC 12228) and five Gram-negative (Proteus mirabilis ATCC 29245, Escherichia coli ATCC 35218, E. coli ATCC 11229, E. coli ATCC 8739, and Bacillus cereus ATCC 11778) bacteria. Arctii folium extracts were the whole ethanol extract/W and subsequent ethyl acetate/EA, aqueous/AQ, and chloroform/CHL fractions. Chemical qualitative analysis (HPTLC method) emphasized five main polyphenol compounds in Arctii folium polar extracts: chlorogenic acid (Rf≈0.52/0.55) and its isomer, 1,5-di-O-caffeoylquinic acid (Rf≈0.90/0.92), plus cynarin (Rf≈0.77), hyperoside (Rf≈0....
Journal of Planar Chromatography – Modern TLC, 2014
Given the large applicability in both pharmaceutical and cosmetic field, this work was aimed at a... more Given the large applicability in both pharmaceutical and cosmetic field, this work was aimed at analytical (high-performance thin-layer chromatography [HPTLC] method), antioxidant (2,2-diphenyl-1-picrylhydrazyl [DPPH] method), and antimicrobial (diffusion method on Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 8739, and Candida albicans ATCC 10231) studies on a series of whole vegetal extracts and corresponding aqueous, ethyl acetate and chloroform fractions (selective extracts) prepared from eight plant species growing in Romania. Briefly, it was revealed moderate to certain activity against S. aureus ATCC 6538 and E. coli ATCC 8739 in the case of greater burdock leaves (Arctium lappa), beech leaves (Fagus sylvatica) and great willowherb aerial part (Epilobium hirsutum) whole extracts. Purple loosestrife aerial part (Lythrum salicaria) and sea-buckthorn leaves (Hippophae rhamnoides) whole extracts showed only weak activity against these bacteria, while tarragon aerial part (Artemisia dracunculoides), chokeberries leaves (Aronia melanocarpa) and quince fruit (Cydonia oblonga) whole extracts have not shown activity. Subsequently studies on the selective extracts have revealed that combinations of glycosides of the same aglycones lead to very different antimicrobial properties indicating synergistic effects between polyphenols (demonstrated in the case of Fagus sylvatica extracts) or the contribution of other phytocompounds to the final effect (demonstrated in the case of Arctium lappa extracts) and, secondly, that the glycosyl chain in which they occur may also contribute to the final antimicrobial effect (demonstrated by the fact that the most active vegetal extracts emphasized the dominance of flavonoid monoglycosides). Moreover, inhibitory antimicrobial effects were revealed (Arctium lappa extracts). Finally, none of the studied extracts acted against C. albicans ATCC 10231. Concerning antioxidant activity, DPPH tests indicated high potency of all tested extracts (IC50 measuring from 2.66 to 4.80). Further studies on the most active vegetal extracts which aim to reveal MICs values and potential inhibitory or activatory effects in combination with chemical antibiotics are ongoing.
Farmacia, 2010
... Most commonly, the vesicles are composed of phospholipids or non-ionic surfactants. ... Porfi... more ... Most commonly, the vesicles are composed of phospholipids or non-ionic surfactants. ... Porfire AS, Pârvu AE, Daicoviciu D., Leucuţa SE, Evaluation of Antiinflamatory Activity of Liposome Encapsulated Superoxide Dismutase in Rats Peritonitis, Farmacia, 2009, 57(4), 412-423. ...
Materiale Plastice
This study was geared to analyze the preparation methods of pullulan acetate-based nanoparticles ... more This study was geared to analyze the preparation methods of pullulan acetate-based nanoparticles loaded with 5-fluorouracil, as well as the potential of pullulan as a biopolymer matrix for obtaining nanoparticles applied in the delivery of anticancer drugs (5-FU). Various methods were used to produce pullulan acetate-based nanoparticles loaded with 5-FU, including nanoprecipitation, modified nanoprecipitation, and double emulsion. Pullulan was previously chemically modified with acetic anhydride, dimethylformamide and pyridine, and yielded pullulan acetate. Pullulan was made using the Aureobasidium pullulans strain through a fermentation procedure. UV-Vis Spectro-photometric and dynamic light scattering (DLS) methods were used to assess entrapment effectiveness, size, and polydispersity index (PDI) of pullulan acetate-based nanoparticles loaded with 5-FU. Based on the properties of the nanoparticles obtained, the optimum preparation method was chosen. The maximum entrapment efficien...
Priochem 2021, 2022
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
2013 E-Health and Bioengineering Conference (EHB), 2013
ABSTRACT Bacterial cellulose (BC) is a biomaterial suited for various biomedical applications, du... more ABSTRACT Bacterial cellulose (BC) is a biomaterial suited for various biomedical applications, due to its unique nanostructure, that confers remarkable physical and chemical properties, such as: excellent elasticity, biocompatibility, high purity, high tensile strength and high elastic modulus. The article describes the mechanism and amoxicillin release profiles from bacterial cellulose-glycerol-poly(vinyl alcohol) composites, in the aim to use such systems in controlled drug delivery field. Obtained data from these composites were slightly smaller than BC-Glycerol, probably due to the fact that PVA layers provide an additional barrier for drug release. The presented data are of interest for the biomaterials community.
Open Chemistry, 2016
Epilobium genus has been confirmed as an effective source of natural antimicrobials. However, the... more Epilobium genus has been confirmed as an effective source of natural antimicrobials. However, the influence of Epilobi hirsuti herba derived products on usual antibiotics activity has not been studied. In this study, several standardized Epilobi hirsuti herba extracts (EHE) were evaluated in order to asses their potential effects on usual antibiotics tested on standard Gram-positive and Gram-negative bacterial strains in vitro. The results emphasized that the bacterial strains ranged from sensitive (MIC values between 50–200 μg GAE mL-1) (S. epidermidis ATCC 12228) to very resistant (E. coli strains), E. faecalis ATCC 29212 being practically immune to EHE. In terms of synergistic interaction, Tetracycline and Ampicillin combinations lead to the most important stimulatory effects, the diameters of the inhibition zone being even 60% bigger compared to the antibiotic alone. Synergistic effects between myricetin(galloyl) derivates and Tetracycline were also revealed on P. aeruginosa and...
Revista de Chimie -Bucharest- Original Edition-
ABSTRACT
Ovidius University Annals of Chemistry
The aim of this research was to investigate the release behavior of a combination of two poorly w... more The aim of this research was to investigate the release behavior of a combination of two poorly water-soluble active pharmaceutical ingredients (APIs) from poly (D,L-lactide-co-glycolide) (PLGA) nanoparticles. Amlodipine besylate - AML, a calcium channel blocker, and valsartan - VAL, an angiotensin II receptor antagonist drug, were used as poorly water-soluble model drugs. PLGA nanoparticles loaded with AML-VAL (1:16 w/w) were obtained by nanoprecipitation using an amphiphilic block copolymer - Pluronic F127 as stabilizer. The drugs release from the PLGA nanoparticles was determined by a dialysis membrane method under sink conditions. Nanoparticles provided a slow release for both APIs and an attenuated burst effect compared to free drug. Five kinetics models such as Zero-order, First-order, Korsmeyer-Peppas, Higuchi and Hixson-Crowell were applied to predict drug release profiles. The Higuchi and Korsmeyer-Peppas models (R2 > 0.97) best described physicochemical release phenomen...
Transdermal administration of drugs is generally limited by the barrier function of the skin. Ves... more Transdermal administration of drugs is generally limited by the barrier function of the skin. Vesicular systems are one of the most controversial methods for transdermal delivery of active substances. The interest in designing transdermal delivery systems was relaunched after the discovery of elastic vesicles: transferosomes and ethosomes. This paper presents the composition, manufacturing and characterization methods, mechanisms of penetration of transferosomes and ethosomes as transdermal delivery systems of active substances. Rezumat Administrarea transdermică a medicamentelor este in principal limitată de funcţionarea pielii ca o barieră. Sistemele veziculare reprezintă una dintre cele mai controversate modalităţi utilizate pentru transportul transdermic al substanţelor active. Interesul pentru proiectarea de sisteme veziculare transdermice a fost relansat după descoperirea veziculelor elastice: transferozomii si etozomii. Acest articol prezintă compoziţiile, metodele de prepara...
of the free acids from the refined ostrich oil and two-step transesterification in alkaline catal... more of the free acids from the refined ostrich oil and two-step transesterification in alkaline catalysis takes place. This process can be used for oils having a free acids value greater than 1%. [7-9].Purification of fatty acid esters obtained from vegetables oils or animal fats is achieved by chromatographic methods, distillation method, low temperature crystallization, enzymatic methods, supercritical fluid extraction, urea complexation [10]. This paper presents our results related to transesterification of fatty acid triglycerides of refined ostrich oil with ethanol, in two step acid-base catalyzed transesterification, in alkaline catalysis and acid catalysis, without prior cleavage of the free fatty acids.
This work aimed to establish Epilobium hirsutum L. (Onagraceae family) aerial part whole and sele... more This work aimed to establish Epilobium hirsutum L. (Onagraceae family) aerial part whole and selective extracts antimicrobial activity and possible synergism with some antibiotics (Gentamicin, Tetracycline, Ampicillin, Nalidixic acid and Ciprofloxacin) tested on standard and wild methicillin‐resistant Staphylococcus aureus (MRSA) strains; the vegetal extracts had identical total phenols content, 5 mg gallic acid (GAE) equivalents 1 mL extract respectively. Thus, there were evidenced stimulatory effects between great willowherb extracts and Ampicillin; statistically significant differences were also obtained for the combination with Gentamicin and Ciprofloxacin, in these cases being recorded smaller inhibition zones compared to those of the antibiotics used alone (inhibitory effects). Rezumat Scopul acestui studiu a constat in evaluarea activităţii antimicrobiene si a unui posibil efect sinergic a unor extracte totale si selective obţinute din partea aeriană de Epilobium hirsutum L. ...
Although less potent than allopathic medicines, anti-inflammatory as well as antimicrobials plant... more Although less potent than allopathic medicines, anti-inflammatory as well as antimicrobials plant derived products are often more effective in treating human illnesses mainly owing phytocompounds synergistic activity. For example, in the specific case of anti-inflammatory activity, there are data proving the synergism between polyphenols and polysaccharides fractions; similarly for antioxidant activity, especially if also combines triterpenic acids in order to increase phytocompounds solubility. In the specific case of antimicrobials, scientific results suggest phenylcarboxylic acid class boosting effect upon flavonoids sub- classes. Given that vegetal world has been always a source of human health (the practice of self-medication using herbs dating from the Palaeolithic) phytocompounds efficacy mechanisms needs to be revealed and further adopted for the design and development of novel highly effective natural or combined medicines.
Nanomaterials
This study is focused on the encapsulation of polyphenols from Lycium barbarum leaves into liposo... more This study is focused on the encapsulation of polyphenols from Lycium barbarum leaves into liposomes as a strategy to improve their delivery. Liposomes loaded with Lycium barbarum leaves extract were obtained and characterized for particle size, polydispersity, entrapment efficiency, and stability. Liposomes presented entrapment efficiency higher than 75%, nanometric particle size, narrow polydispersity, and good stability over three months at 4 °C. The liposomes containing Lycium barbarum offered a slower release of polyphenols with attenuated burst effect compared with the dissolution of free Lycium barbarum extract in phosphate buffer solution at pH 7.4. Moreover, an in vitro pretreatment of 24 h with loaded liposomes showed a cytoprotective effect against H2O2-induced cytotoxicity on L-929 mouse fibroblasts cells. These preliminary findings imply that liposomes could be successfully employed as carriers for polyphenols in pharmaceutical applications.
Chemistry Proceedings
The objective of this paper is to develop polymeric nanoparticles loaded with a cardiovascular dr... more The objective of this paper is to develop polymeric nanoparticles loaded with a cardiovascular drug (an angiotensin II receptor blocker, valsartan). Polymeric nanoparticles were prepared via the nanoprecipitation method using pullulan acetate as biodegradable polymeric matrix and Pluronic F127 as a stabilizer. Pullulan acetate was obtained through the chemical modification of pullulan (produced through a fermentation process using the Aureobasidium pullulans strain) with dimethylformamide, pyridine and acetic anhydride. The obtained nanoparticles were characterized in terms of entrapment efficiency, size, and polydispersity index using spectrophotometric and dynamic light scattering techniques. The valsartan-loaded nanoparticles showed a good entrapment efficiency of valsartan, nanometric sizes (lower than 200 nm), and a narrow dispersity (polydispersity index below 0.2). This research revealed that pullulan and pullulan derivatives show great potential for the production of nanopar...
Proceedings
Nanomedicine is a rapidly growing field that uses nanotechnology to solve clinical problems— [...]
Proceedings
Cancer is the second leading cause of death worldwide and one of the most challenging [...]
Proceedings
Dermacosmetic products help alleviate certain conditions. [...]
Revista de Chimie
The aim of this paper was the design and evaluation of delivery system for Armoracia rusticana le... more The aim of this paper was the design and evaluation of delivery system for Armoracia rusticana leaves extract with the purpose to use such systems in food or cosmetic field. Liposomes loaded with Armoracia rusticana were prepared by film hydration method and presented good entrapment efficiency, nano-sizes ([150 nm), low polydispersity index and good stability over 90 days at 4oC. In vitro drug release study showed the ability of liposomes to provide slow release of extract with reduced burst effect compared to free extract. These promising results suggest that liposomes could be exploited as carriers for herbal ingredients.
Materiale Plastice
The main aim of this study was to prepare and characterize polymeric nanoparticles containing two... more The main aim of this study was to prepare and characterize polymeric nanoparticles containing two cardiovascular active pharmaceutical ingredients: valsartan (VAL) and amlodipine besylate (AML). Six formulations were evaluated with different ratios of AML:VAL:PLGA (1:16:17, 1:16:34, and 1:16:51) and different stirring speed (1200 and 2400 rpm). Encapsulation efficiency (EE, %) and particle size analyses were performed to characterize and optimize the formulation. All loaded nanoparticles showed a high EE (%), nano-size, negative x-potential and a high homogeneity.
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Papers by Cristina Hlevca