Jelena Ostojić

Ms. Jelena Ostojić

orcid

Research Focus & Metrics

Academic Career Length

13Years (2014-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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5 July 2017 in Molecules
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Journal Article
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JOJelena Ostojić
Jelena Ostojić
SHSafija Herenda
Safija Herenda
ZBZerina Bešić
Zerina Bešić
MMMladen Milos
Mladen Milos
BGBorivoj Galić
Borivoj Galić
In this study, boroxine derivative (K2[B3O3F4OH]) was tested as an inhibitor of horseradish peroxidase (HRP) by spectrophotometric and electrochemical methods. The activity of horseradish peroxidase was first studied under steady-state kinetic conditions by a spectrophotometric method which required the use of guaiacol as a second substrate to measure guaiacol peroxidation. The results of this method have shown that, by changing the concentration of guaiacol as the literature suggests, a different type of inhibition is observed than when changing the concentration of hydrogen peroxide as the substrate. This suggests that guaiacol interferes with the reaction in some way. The electrochemical method involves direct electron transfer of HRP immobilized in Nafion nanocomposite films on a glassy carbon (GC) electrode, creating a sensor with an electro-catalytic response to the reduction of hydrogen peroxide. The electrochemical method simplifies kinetic assays by removing the requirement of reducing substrates.

18 June 2014 in Journal of Enzyme Inhibition and Medicinal Chemistry
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SISinisa Ivankovic
Sinisa Ivankovic
RSRanko Stojković
Ranko Stojković
ZGZoran Galic
Zoran Galic
BGBorivoj Galic
Borivoj Galic
JOJelena Ostojić
Jelena Ostojić
MMMladen Milos
Mladen Milos
Dipotassium-trioxohydroxytetrafluorotriborate K2[B3O3F4OH] was listed as a promising new therapeutic for cancer diseases. For in vitro and in vivo investigation of its antitumor effects 4T1 mammary adenocarcinoma, B16F10 melanoma and squamous cell carcinoma SCCVII were used. The detailed in vitro investigation undoubtedly showed that K2[B3O3F4OH] affects the growth of cancer cells. The proliferation of cells depends on the concentration so that aqueous solution of K2[B3O3F4OH], the concentrations of 10(-4) M and less, does not affect cell growth, but the concentrations of 10(-3) M or more, significantly slows cells growth. B16F10 and SCCVII cells show higher sensitivity to the cytotoxic effects of K2[B3O3F4OH] compared to 4T1 cells. Under in vivo conditions, K2[B3O3F4OH] slows the growth of all three tumors tested compared to the control, and the inhibitory effect was most pronounced during the application of the substance. There is almost no difference if K2[B3O3F4OH] was applied intraperitoneally, intratumor, peroral or as ointment. Addition of 5-FU did not further increase the antitumor efficacy of K2[B3O3F4OH].

1 January 2017 in Journal of Chemistry
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JOJelena Ostojić
Jelena Ostojić
SHSafija Herenda
Safija Herenda
SGSemira Galijašević
Semira Galijašević
BGBorivoj Galic
Borivoj Galic
MMMladen Milos
Mladen Milos
Recently research shows that horseradish peroxidase, HRP, when combined with other compounds, is highly reactive toward different human tumour cells and that better understanding of catalytic mechanism and inhibition HPR could lead to a new targeted cancer therapy. Thus, the inhibition of HRP activity by dipotassium-trioxohydroxytetrafluorotriborate K2[B3O3F4OH] was investigated for possible explanation of previously observed antitumour activities of this promising drug. HRP activity was studied under steady-state kinetic conditions by a spectrophotometric method. In the absence of the inhibitor values of Km = 0.47 mM and Vmax = 0.34 mM min−1, respectively, were determined. The hydrogen peroxide H2O2 kinetic measurements show a competitive inhibition with the inhibition constant KI = 2.56 mM. The activation energy Ea values were found to be very similar for both reactions; in the absence of inhibitor activation energy was 17.7 kJ mol−1 and in the presence of inhibitor activation energy was 16.3 kJ mol−1. The values of Arrhenius constants were found to be different; A = 4.635 s−1 was measured in the absence of inhibitor while in the presence of inhibitor Arrhenius constant was 1.745 s−1 showing that K2[B3O3F4OH] initiates conformational change in the structure of the HRP and subsequently reduces its activity.

24 April 2023 in Metallic Materials
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MÐMaja Ðekić
Maja Ðekić
JOJelena Ostojić
Jelena Ostojić
HSHađer Sinanović
Hađer Sinanović
FKFehim Korać
Fehim Korać
AFAmra Salčinovic Fetić
Amra Salčinovic Fetić

6 November 2025 in Monatshefte für Chemie - Chemical Monthly
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JOJelena Ostojić
Jelena Ostojić
SHSafija Herenda
Safija Herenda
SGSabina Gojak-Salimović
Sabina Gojak-Salimović
SPSanja Pržulj
Sanja Pržulj
SGSemira Galijasevic
Semira Galijasevic
MMMladen Miloš
Mladen Miloš

27 December 2022
Verified
Conference Paper
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LKLejla Klepo
Lejla Klepo
JOJelena Ostojić
Jelena Ostojić
OBOlga Borota
Olga Borota
SŽSabina Žero
Sabina Žero
DCDusan Culum
Dusan Culum
Pyrophyllite was investigated in this study as a potential adsorbent for the removal of glyphosate, a common herbicide for the control of a wide variety of weeds. There are several publications in the literature that discuss how glyphosate interacts with clay minerals such as montmorillonite, kaolinite, and bentonite, but there is no information regarding the possibility of glyphosate removal from aqueous solution using pyrophyllite. In this study, the adsorption of glyphosate from water samples onto pyrophyllite, a mineral clay from the Parsovici, Konjic mine, was investigated. The ninhydrin reaction was used to spectrophotometrically quantify glyphosate. At 570 nm, the purple Ruhemman product's absorbance was determined. Adsorption capacity (qe), removal efficiency (R), and the partition coefficient are used to express the results (Kd). The outcomes demonstrated that distinct ionic species of glyphosate at different pHs cause the adsorption of glyphosate on pyrophyllite to be pH-dependent. The findings demonstrated that during different contact times, the basic medium can remove up to 75% of glyphosate. According to results from fitting isotherm models, the Freundlich model is slightly better fitted. According to the results of kinetic investigations, the pseudo-2nd order model is more suitable for this kind of adsorption.