1. Identification and content of astaxanthin and its esters from microalgae Haematococcus pluvialis by HPLC-DAD and LC-QTOF-MS after extraction with various solventsBiljana Todorović, Jaša Veno Grujić, Andreja Urbanek Krajnc, Roman Kranvogl, Jana Ambrožič-Dolinšek, 2021, izvirni znanstveni članek Opis: Haematococcus pluvialis, a unicellular green microalga that produces a secondary metabolite under stress conditions, bears one of the most potent antioxidants, namely xanthophyll astaxanthin. The aim of our study was to determine the content of astaxanthin and its esterified forms using three different solvents—methyl tert-butyl ether (MTBE), hexane isopropanol (HEX -IPA) and acetone (ACE)—and to identify them by using high performance liquid chromatography coupled with diode array detection and the quadrupole time-of-flight mass spectrometry (HPLC-DAD and LC-QTOF-MS) technique. We identified eleven astaxanthin monoesters, which accounted for 78.8% of the total astaxanthin pool, six astaxanthin diesters (20.5% of total), while free astaxanthin represented the smallest fraction (0.7%). Astaxanthin monoesters (C16:2, C16:1, C16:0), which were the major bioactive compounds in the H. pluvialis samples studied, ranged from 10.2 to 11.8 mg g−1 DW. Astaxanthin diesters (C18:4/C18:3, C18:1/C18:3) were detected in the range between 2.3 and 2.6 mg g−1 DW. All three solvents were found to be effective for extraction, but MTBE and hexane-isopropanol extracted the greatest amount of free bioactive astaxanthin. Furthermore, MTBE extracted more low-chain astaxanthin monoesters (C16), and hexane-isopropanol extracted more long-chain monoesters (C18 and above) and more diesters. We can conclude that MTBE is the solvent of choice for the extraction of monoesters and hexane-isopropanol for diesters.
Ključne besede: astaxanthin diesters, astaxanthin monoesters, carotenoids, Hematococcus pluvialis, astaxanthin diesters, solvent extraction
Objavljeno v DKUM: 22.11.2024; Ogledov: 0; Prenosov: 5
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2. Diversity and content of carotenoids and other pigments in the transition from the green to the red stage of Haematococcus pluvialis microalgae identified by HPLC-DAD and LC-QTOF-MSJaša Veno Grujić, Biljana Todorović, Roman Kranvogl, Terezija Ciringer, Jana Ambrožič-Dolinšek, 2022, izvirni znanstveni članek Opis: H. pluvialis is a unicellular freshwater alga containing many bioactive compounds, especially carotenoids, which are the strongest antioxidants among the pigments. This study evaluates
the composition and content of carotenoids and other pigments in both stages of algae life cycle,
especially in the green vegetative stage, less studied in comparison to the red stage. To determine
the composition and content of carotenoids, a combination of HPLC-DAD and LC-QTOF-MS was
used. The content of carotenoids in the green vegetative stage was significantly lower than in the
red vegetative stage. In the green vegetative stage, 16 different carotenoids and other pigments were
identified. Among the total 8.86 mg g−1 DW of pigments, 5.24 mg g−1 DW or 59% of them were
chlorophyll a with its derivatives, and 3.62 mg g−1 DW or 41% of them were free carotenoids. After
the transition from the green to the red stage, the carotenoid composition was replaced by secondary
carotenoids, astaxanthin and its esters, which predominated in the whole carotenoid composition.
In addition to free astaxanthin, 12 astaxanthin monoesters, 6 diesters and 13 other carotenoids were
determined. The majority of 37.86 mg g−1 DW pigments were monoesters. They represented 82% of
all pigments, and their content was about 5 times higher than both, diesters (5.91 mg g−1 DW or 12%
of all) and free carotenoids (2.4 mg g−1 DW or 6% of all). The results of the study contribute to the
data on the overall pigment composition and content of H. pluvialis algae and provide the basis for
further improvement of cultivation of the H. pluvialis algae.
Ključne besede: antioxidants, astaxanthin, chlorophylls, bioactive compounds, algae, Haematococcus, life cycle, pigment composition, secondary carotenoids
Objavljeno v DKUM: 21.05.2024; Ogledov: 172; Prenosov: 13
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3. The potential of berula erecta in vitro for As bioaccumulation and phytoremediation of water environmentsJana Ambrožič-Dolinšek, Anja Podgrajšek, Nik Šabeder, Zdenka Mazej, Andreja Urbanek Krajnc, Biljana Todorović, Terezija Ciringer, 2023, izvirni znanstveni članek Opis: A potential plant species suitable for As bioaccumulation and phytoremediation of water environments could be the macrophyte Berula erecta. The objective of the present study was to investigate the effect of arsenate (As(V), C2H6AsNaO2∙3 H2O), predominant in freshwater systems, on the growth, development and low molecular weight thiols of Berula erecta under controlled tissue culture conditions in vitro. Uptake of total arsenate increased with increasing arsenate treatments, at a higher percentage in the roots than in the aboveground parts of the plants. Lower concentrations of As(V) (0.1, 1, 10 mg L−1) had a positive effect on growth, dry weight, length of roots and shoots and number of buds. High concentrations of arsenate (50 and 100 mg As(V) L−1) significantly inhibited all growth parameters and decreased the photochemical efficiency of PSII. Evaluation of thiols revealed the critical As level (146 µg g−1 DW; 50 mg As(V) L−1 treatment) above which the As concentration can be toxic.
Ključne besede: arsenic, arsenate, uptake, accumulation, thiols, apiaceae, lesser water-parsnip
Objavljeno v DKUM: 02.08.2023; Ogledov: 446; Prenosov: 95
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5. UPORABA PCA METODE PRI VREDNOTENJU VPLIVA POLOŽAJA PLODOV V KROŠNJI NA LASTNOSTI PRIDELKA PLODOV RAZLIČNIH SORT JABLAN (Malus domestica B.)Biljana Todorović, 2011, magistrsko delo Opis: Uporaba PCA metode pri vrednotenju vpliva položaja plodov v krošnji na lastnosti pridelka plodov različnih sort jablan (Malus domestica B.)
UDK: 634.11:519.87: 631.524. 7(043)=863
V Sadjarskem centru Maribor (Gačnik) in na posestvu UKC Pohorski dvor je bila v letu 2009 izvedena raziskava z namenom ovrednotiti vpliv položaja ploda v krošnji na nekatere parametre zrelosti in kakovosti pridelka jablan sort ′Gala′, ′Elstar′, ′Jonagold′, ′Braeburn′ in ′Fuji′. Sončni položaj je bil definiran kot položaj na obodu krošnje, polsenčni položaj med obodom krošnje in deblom in senčni položaj tik ob deblu. Za obdelavo podatkov sta bili uporabljeni PCA analiza in ANOVA. Skupna PCA analiza podatkov vseh petih sort jablan je pokazala močan vpliv položaja ploda v krošnji na testirane parametre zrelosti in kakovosti plodov (pojasnjeno 61 % variance). Pri vseh petih sortah je imel položaj ploda v krošnji signifikanten vpliv na intenzivnost obarvanosti povrhnjice, vsebnost topne suhe snovi in povprečno maso plodov, tako da so bili plodovi na sončnem položaju bolje obarvani, slajši in so dosegli večjo povprečno maso. Pri sortah 'Elstar' in 'Braeburn' so bili na sončnem položaju plodovi tudi trši in zrelejši. Pri sorti 'Fuji' je bila zrelost plodov najmanj odvisna od njihovega položaja v krošnji.
Ključne besede: jablana, PCA metoda, položaj plodov, kakovost, zrelost
Objavljeno v DKUM: 29.06.2011; Ogledov: 2989; Prenosov: 249
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6. Trženje in sponzoriranje v slovenskem namiznem tenisu : diplomsko deloBiljana Todorović, 2003, diplomsko delo Ključne besede: trženje, marketing, sponzorstvo, financiranje, šport, odnosi z javnostjo, organizacija, strateško upravljanje, poslovne funkcije, komuniciranje, marketing mix, marketinški splet, trg, pogodbe, Slovenija, oglaševanje, ekonomska propaganda, mediji, avdiovizualna sredstva, radio, televizija, tisk, predstava
Objavljeno v DKUM: 28.09.2007; Ogledov: 3678; Prenosov: 348
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