Neven Zarković

Ruđer Bošković Institute, Zagreb, Grad Zagreb, Croatia

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Publications (5)9.66 Total impact

  • Article: Even stressed cells are individuals: second messengers of free radicals in pathophysiology of cancer.
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    ABSTRACT: Pathophysiological processes associated with disturbances in cell and tissue oxidative homeostasis, are associated with self-catalyzed process of lipid peroxidation. The end products of lipid peroxidation are reactive aldehydes such as 4-hydroxy-2-nonenal (HNE), acting as "second messengers of free radicals." Although reactive aldehydes were first recognized only as cytotoxic, new evidence has come to light, related to their cell growth regulatory functions achieved through cell signaling. The variable appearance of HNE in several organs indicates that its mode of action might be related to an individual cell stress adaptation. The underlying mechanism could be that specific mutations and epigenetic changes on one hand interfere with hormesis on the other. The precise role of oxidative stress and lipid peroxidation in these processes still needs more clarification at molecular level. Finally, an individual approach to each patient, based on the individual cell response to stress, opens a new possibility of integrative medicine in cancer treatment and strongly supports modern concepts of personalized medicine.
    Croatian Medical Journal 08/2012; 53(4):304-9. · 1.80 Impact Factor
  • Article: Growth modulation of human cells in vitro by mild oxidative stress and 1,4-dihydropyridine derivative antioxidants.
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    ABSTRACT: Reactive oxygen species and lipid peroxidation products are not only cytotoxic but may also modulate signal transduction in cells. Accordingly, antioxidants may be considered as modifiers of cellular redox signaling. Therefore, the effects of two novel synthetic antioxidants, analogues of 1,4-dihydropyridine derivatives, cerebrocrast and Z41-74 were analysed in vitro on human osteosarcoma cell line HOS, the growth of which can be modulated by lipid peroxidation. The cells were pretreated with either cerebrocrast or Z41-74 and afterwards exposed to mild, copper induced lipid peroxidation or to 4-hydroxynonenal (HNE), the end product of lipid peroxidation. The results obtained have shown that both antioxidants exert growth modulating effects interfering with the lipid peroxidation. Namely, cells treated with antioxidants showed increased metabolic rate and cell growth, thereby attenuating the effects of lipid peroxidation. Such biomodulating effects of cerebrocrast and Z41-74 resembled growth modulating effects of HNE, suggesting that the antioxidants could eventually promote cellular adaptation to oxidative stress interacting with redox signaling and hydroxynonenal HNE-signal transduction pathways. This may be of particular relevance for better understanding the beneficial role of hydroxynonenal HNE in cell growth control. Therefore, cerebrocrast and Z41-74 could be convenient to study further oxidative homeostasis involving lipid peroxidation.
    Collegium antropologicum 03/2011; 35(1):137-41. · 0.61 Impact Factor
  • Article: Natural and synthetic antioxidants: an updated overview.
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    ABSTRACT: Abstract The current understanding of the complex role of ROS in the organism and pathological sequelae of oxidative stress points to the necessity of comprehensive studies of antioxidant reactivities and interactions with cellular constituents. Studies of antioxidants performed within the COST B-35 action has concerned the search for new natural antioxidants, synthesis of new antioxidant compounds and evaluation and elucidation of mechanisms of action of both natural and synthetic antioxidants. Representative studies presented in the review concern antioxidant properties of various kinds of tea, the search for new antioxidants of herbal origin, modification of tocopherols and their use in combination with selenium and properties of two promising groups of synthetic antioxidants: derivatives of stobadine and derivatives of 1,4-dihydropyridine.
    Free radical research 10/2010; 44(10):1216-62. · 2.22 Impact Factor
  • Article: Cyp4a14 overexpression induced by hyperoxia in female CBA mice as a possible contributor of increased resistance to oxidative stress.
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    ABSTRACT: The beneficial effects of hyperoxia have been noted in treatment of several diseases and pathological states. However, the excessive production of ROS under hyperoxic conditions can directly damage cellular macromolecules if the imbalance in antioxidant status exists. Cytochrome P450 (Cyp) 4a14 has an important role in the metabolism of lipids and as a source of ROS in oxidative stress. This study investigated the oxidant/antioxidant status as a response to hyperoxia treatment in liver of young CBA/Hr mice of both sexes and whether the observed response is mediated by Cyp4a14 via PPAR isoforms in a sex-dependent manner. The overexpression of Cyp4a14, lack of both LPO and of 4-hydroxynonenal(HNE)-protein adducts revealed by immunohistochemical analysis in hyperoxia-treated females indicates their greater resistance to hyperoxia compared to males, which is parallelled to changes in PPARbeta/delta and PPARgamma expression. These results suggest the presence of sex-dependent changes in all investigated parameters, which points out sex-related susceptibility towards oxidative stress and hyperoxia treatment of various pathological conditions and diseases.
    Free radical research 11/2009; 44(2):181-90. · 2.22 Impact Factor
  • Article: Comparative study on the antioxidant and biological activities of carvacrol, thymol, and eugenol derivatives.
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    ABSTRACT: Four derivatives of thymol, carvacrol, and eugenol were synthesized: 4-(hydroxymethyl)-5-isopropyl-2-methylphenol, 4,4'-methylenebis(5-isopropyl-2-methyl)phenol, 4-allyl-6-(hydroxymethyl)-2-methoxyphenol, and 4-(hydroxymethyl)-2-isopropyl-5-methylphenol. The obtained derivatives showed remarkably better antioxidative properties according to 1,1-diphenyl-2-picrylhydrazyl assay (50% inhibitory concentrations = 4-156 microg/mL) and Rancimat assay (protection factors = 1.55-5.84) when compared with parent compounds and values similar to or better than those of butylated hydroxytoluene and vitamin C. At concentrations of 10 mM carvacrol derivatives had no toxic effect on viability of Escherichia coli K-12 (determined by minimum inhibitory concentrations). Other phenol derivatives showed reduced cytotoxic effect on E. coli K-12 at concentrations of 2-5 mM on the basis of 50% lethal dose measurements. In comparison with the parent compounds, phenol derivatives showed reduced cytotoxic effect for Saccharomyces cerevisiae cells (determined by yeast colony reduction). On the other hand, the majority of synthesized compounds had dose-dependent antiproliferative effects on human uterine carcinoma cells (HeLa), which makes them potentially interesting for the adjuvant experimental cancer treatments. The 4,4'-methylenebis(5-isopropyl-2-methyl)phenol derivative of carvacrol showed lower inhibiting capacity also for the HeLa cells, which makes this particular derivative attractive as an efficient antioxidant with negligible cytotoxic effects.
    Journal of Agricultural and Food Chemistry 07/2008; 56(11):3989-96. · 2.82 Impact Factor