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U radu su detaljno prezentirani podaci o realnom stanju svjetskog i hrvatskog vinogradarstva i vinarstva.

Sensitivity of natural fibers to biological deteriorants is a serious problem in protecting textile heritage objects. Radiation treatment is a common method of pest control and decontamination. In processing of objects of cultural heritage doses are selected according to contamination - up to 0.5 kGy for disinsection, 4-10 kGy for fungi control and 5-20 kGy ensures microbiological decontamination. Along with many other cultural heritage objects, textile items mainly ethnological significance were treated in 60Co gamma radiation source Ruder Boskovic Institute in Zagreb, Croatia [2] and were efficiently disinsected by applying of radiation dose of less than 2 kGy . In order to meet the high standards of conservators possible effects of higher doses should be assesed. Tests were conducted onmodel samples of the most commonmaterials in heritage items - silk, flax cotton, and wool. To ensure that any of the radiation effects will be observed a high dose of D=120 kGy in contact with air was applied. A part of the samples were heat- or UV - aged before exposure to γ- irradiation. Changes were determined by thermal analysis: differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results indicated that even such a large doses caused almost no change in the materials based on protein fibers (silk, wool, while those based on cellulose (cotton, flax showed somewhat reduced thermal stability on irradiation. SEM images confirmed those observations. Despite the high dose changes due to radiation were comparable to or lesser than those caused artificial aging. Based on these results it can be concluded that the radiation treatment iof heritage textile materials will not cause damage if performed fat the doses needed for controlling fungi.

Various commodities predominantly crops can be contaminated with moulds that can lead to economic losses in agriculture and in food industry. More importantly, some moulds produce mycotoxins, their toxic secondary metabolites, indicating that mould except economic loss can represent threat to animal and human health. Oneof the most toxic mycotoxin is aflatoxin B1 (AFB1) with hepatotoxic, teratogenic, immunosuppressive and carcinogenic properties. Due to its toxicity International Agency for Research on Cancer (IARC) classified AFB1 in group 1 as carcinogenic to humans. Countries around the world have limited the maximal level of mycotoxins in different food and feed commodities and in EU maximal tolerable level of AFB1in cereals and cereal-based products is set to 2.0 μg/kg. The level of AFB1in various commodities depends on climatic conditions under which the crops are harvested, stored and processed and higher AFB1level can be expected with higher humidity and temperature that favourable mould growth. It is important to try to control growth of moulds that can produce AFB1, or at least to keep their growth and production of AFB1to minimum. It is known that gamma irradiation could be effective in inactivating the growth of moulds, thus reducing AFB1level in commoditiesindirectly. The aim of this study was to investigate if gamma irradiation can be use as a method for direct reduction of AFB1level in corn/feed samples intended for animal consumption. For this purpose two separated experiments were performed. In the first experiment corn seeds, ground corn seeds and feed samples were artificially contaminated with known AFB1concentration (50 or 100 μg/kg), that can be expected in nature. For the second experiments corn seeds samples (n=30) naturally contaminated with AFB1and intended for animal consumption were collected inEastern part of Croatia. In both experiments gamma irradiation at 5 and 10 kGy were tested. Results of first experiment showed that gamma irradiation of feed samples with added AFB1at dose of 5 kGy reduced AFB1level for around 65%, while at dose of 10 kGy AFB1level was reduced for around 85%. In naturally contaminated corn samples overall reduction of AFB1level after 5 kGy irradiation was 69.8% while the overall mean toxin reduction was 94.5% when 10 kGy was applied. Together, these results indicate that gamma irradiation can be used in reducing AFB1level in various commodities intended for animal and human consumption thus minimizing animal and human exposures to this carcinogenic mycotoxin.

Different types of lipid aggregations, such as micelles and liposomes, can be used as biomimetic models. The uses of gamma irradiation as a valid methodology for simulating the biological generation of thiyl radicals in these models are summarized and in particular, thiyl radical-catalyzed cis–trans isomerization of unsaturated lipids is underlined. The efficiency of antioxidants against lipid isomerization assayed by biomimetic models and the importance of trans lipids as novel biomarkers of radical stress are also described.

Plijesni su mikroskopske gljive koje kontaminiraju namirnice, prvenstveno žitarice već na polju, ali i za vrijeme skladištenja te stoga uzrokuju velike gospodarske gubitke u poljoprivrednoj i prehrambenoj industriji. Jedne od najrasprostranjenijih plijesni zagađivača hrane su i plijesni roda Aspergillus. Aflatoksini, mikotoksini koje sintetiziraju plijesni roda Aspergillus jedni su od najtoksičnijih mikotoksina. Njihova toksičnost pokazana je na domaćim i pokusnim životinjama, a utvrđeno je da u ljudi uzrokuju karcinom jetre. Gama (γ) zračenje je fizikalna metoda koja se koristi za mikrobiološku dekontaminaciju sirovina namijenjenih farmaceutskoj, kozmetičkoj i prehrambenoj industriji te za sterilizaciju medicinskog pribora. U ovome istraživanju ispitivan je utjecaj γ zračenja na rast plijesni roda Aspergillus. Cilj istraživanja bio je utvrditi najnižu dozu γ zračenja koja bi uspješno zaustavila rast plijesni roda Aspergillus pa time i biosintezu mikotoksina aflatoksina.

The aim of this study was to determine the rate of monounsaturated fatty acids (MUFAs) in the liver of Tff3 knock-out mice, as well as the serum glucose and lipid content. We found that: Tff3 knock-out mice compared to WT mice have significantly lower amount of MUFAs in the liver Total serum levels of the cholesterol, triglycerides, HDL or LDL cholesterol did not differ between WT and TFF3 defcient mice. Postprandial glucose levels in Tff3 knock-out mice were higher than in controls but did not reach statistical significance. Microscopic analysis of the liver sections revealed normal tissue architecture (HE) and glycogen reserves (PAS staining).

Cultural heritage artefacts made of organic materials are susceptible to deterioration caused by the action of insects, moulds, fungi and bacteria. The problem of biodeterioration becomes especially acute after natural catastrophies and weather inclemencies, or after human activities conducive to an abrupt development of pests. Usually a large number of objects are imperilled at the same time and their sheer number aggravates any organized preservation effort. Irradiation has proven an effective method of preservation under the circumstances, e.g. for the prevention of massive proliferation of fungal infestation of books wetted by flood. War destructions in Croatia 1991 - 1995 seriously jeopardized many cultural objects. Their treatment by 60Co gamma rays in the Radiation Chemistry and Dosimetry Laboratory of the Ruđer Bošković Institute played a significant role in the prevention of massive biodeterioration. In co-operation with the Croatian Conservation Institute, one third of 5000 evacuated objects, mostly polychromic wooden sculptures, were irradiated for desinsection and disinfection, enabling their joint accommodation in depots until restauration. This contribution to the preservation of jeopardized cultural heritage objects has been recognized internationally as a specially significant and successful case of the application of irradiation to cultural heritage.

Kontinuirano provjeravanje osjetilnih sposobnosti i znanja senzornih ocjenjivača obvezni je dio potvrđivanja kakvoće njihovog rada. Hrvatski certificirani degustatori potvrđuju svoje sposobnosti i znanje kroz obveznu kontinuiranu provjeru, prema uvjetima Ministarstva poljoprivrede. U tu svrhu koriste se različite metode uz statističku obradu podataka. Uz apsolutnu metodu „100 pozitivnih bodova“ kojom se ocjenjuju vina i za promet, koriste se različite usporedne metode, međunarodno standardizirane (ISO 6658). Cilj ovog istraživanja je usporediti rad hrvatskih i austrijskih certificiranih degustatora, u uvjetima akreditiranim prema ISO/IEC 17025, s ciljem potvrđivanja njihovog rada na međunarodnoj razini.. Degustatori koji ocjenjuju vina za dobivanje rješenja za promet, u obje države, ocjenjivali su vina deskriptivnom analizom (DA). DA, u odnosu na sve ostale metode u senzorici, nastoji opisati sva prepoznata svojstva i može biti vrlo dobar alat u istraživačkom radu. U prvom krugu suradnje analizirana su dva vina ; austrijsko crno (Zweigelt) i hrvatsko bijelo (Graševina), iste berbe (2012.) i kakvoće (kvalitetno vino), u istom mjesecu, prema deskriptorima koji se koriste u BAWB. Vrednovani su parametri vanjskog izgleda (boje), mirisa i okusa, unutar kojih su definirane različite grupe mirisa i pojedinačni mirisi, te specifični parametri koji se vežu uz „terroir“ i opći dojam. Na ljestvici rangiranja od 1 (loše) do 5 (izvrsno) vrednovana su 33 svojstva kod bijelog i 51 svojstvo kod crnog vina, s opisima značenja rangiranja za pojedina svojstva. Rezultati ispitivanja statistički su obrađeni. Dobiveni preliminarni rezultati pokazuju izvrsnu ujednačenost kriterija vrednovanja svih parametara vanjskog izgleda, ukupnosti arome, pojedinih svojstava okusa, te općeg dojma kakvoće. Vrlo dobro poklapanje rezultata utvrđeno je za manji broj ispitivanih svojstava, specifičnih za „terroir“ (arome koje se povezuju s tipovima tala). Unatoč činjenici da su i austrijski i hrvatski ocjenjivači opisivali vina sorata koje nisu između vodećih u njihovim državama, preliminarni rezultati pokazuju značajnu ujednačenost u kriterijima deskriptivnog vrednovanja kakvoće, što se može objasniti činjenicom da ovo ispitivanje kakvoće provode eksperti.

Radiation decontamination offers fast and effective protection to damaged cultural heritage (CH) objects. Due to wider availability of irradiation sources like 60Co gamma radiation the treatment of CH objects became important in 1970's. At Laboratory for Radiation Chemistry and Dosimetry, (LRCD), Ruđer Bošković Institute, Zagreb, Croatia where CH objects are being treated for almost 25 years [1]. Linear accelerator of electrons (LINAC) is another common type of irradiator that is somewhat less suitable for heritage treatment because of lower penetration and homogeneity of electron beam. Radiation treatment has numerous advantages like radiation being a very effective and universal biocide with almost unlimited penetration, temperature independent, leaving no residues and not inducing secondary radioactivity. CH objects may be packed during treatment to protect them and to prevent recontamination. Radiation consolidation is also an option. In disastrous situations decontamination of CH objects may be necessary to ensure safety of restores and other personnel that handles it. Contaminant response to irradiation is based on experiences attained in radiation sterilization and sanitization of medical materials, pharmaceuticals, food and the like. In processing of CH objects doses are selected according to contamination - up to 0.5 kGy for disinsection, 4-10 kGy for fungi control while 5-20 kGy ensures microbiological decontamination. The dose may be fine tuned depending on the materials that constitute the object and its state. The decision is usually made by irradiation plant staff, in cooperation with restorer and other specialists. In radiation treatment of heritage objects special consideration should be given to protection from any unwanted side effects. In disastrous circumstances fungi and bacteria are likely contaminants so higher doses may be required. In order to meet the high standards of conservators and restores the effects of such doses should be assessed for a particular cultural heritage object. Because of that the knowledge of the material response to irradiation is of utmost importance. The most recent knowledge on the subject will be presented. For example, plain wooden objects can withstand any desired radiation dose other materials are less radiation resistant, especially paper and some textiles. Pigments, varnishes, glass, decorative stones and other ornaments made of various materials that have diverse radiation sensitivities are often present on the same object. The extent of inflicted damage to the heritage object has also to be taken into account when deciding on the radiation dose to be applied. At LRCD we are recently begun investigation of radiation effects in selected materials that are common constituents of CH objects like textiles since sensitivity of natural fibers to biological deteriorants is a serious problem. Examples of studies [2, 3] performed on model and authentic CH textiles will be presented. The tests were conducted on model samples of the most common textile materials in CH items. To ensure that the radiation effects will be observed a high dose in contact with air was applied. A part of the model samples were heat- or UV -aged before exposure to γ-irradiation. Changes were determined by a number of analytical techniques The results indicated that even a dose more than 20 times higher than otherwise recommended caused only slight changes comparable to or lesser than those caused artificial aging. That is another confirmation that textile CH items can be safely radiation treated for fungi control and probably microbiological decontaminated what is especially important in catastrophic circumstances. [1] B. Katušin-Ražem, D. Ražem, M. Braun, Radiat. Phys. Chem. 78 (2009), 7/8 ; 729-731. [2] K. Kavkler, A. Demšar, Polym. Degrad. Stab. 97 (2012), 5 ; 786-792. [3] I. Pucić, K. Kavkler, B. Mihaljević, to be published

Physical and emotional stress, metabolic alterations, infections, carcinogenesis or inflammation are conditions that can trigger overproduction of reactive oxygen species. Increase of reactive oxygen species, free radicals and/or decreased antioxidant defense result in the misbalance in the cell redox reactions i.e. in the state termed the oxidative stress. The reactive oxygen species are continuously formed in small quantities during the normal metabolism of cell, however their overproduction is cytotoxic and damages macromolecules (DNA, proteins, sugars and lipids). Polyunsaturated fatty acids that are the main constituents of cell membranes are subject to free radicals induced-lipid peroxidation resulting in the destruction of biomembranes. Oxidative stress triggers a cellular stress response thereby activating a number of the redox-sensitive signaling cascades. A low levels oxidative stress induces protective effects but at high levels it may lead to more damaging effects. Quantification of lipid peroxidation or determination of the concentrations of lipid oxidation products is essential to assess the role of oxidative injury in pathophysiological disorders. One of initial products are lipid hydroperoxides (LOOH) which are well known to initiate further autoxidations during reactions of their production and decomposition. One of the pathways for excessive production of free radicals is decomposition of LOOH catalyzed by iron. The small pool of non-bound ferrous iron in cells is known to provide one of the active species involved in probably the most important route for free radical formation leading to increased levels of lipid peroxidation. Although both reactions of LOOH decomposition in the presence of iron realize in biological systems, reduction of LOOH with Fe2+ is more feasible than oxidation of LOOH with Fe3+. Spectrophotometric quantitative determination of LOOH is used to follow accurately the initial or early stages of the lipid peroxidation process. The spectrophotometric method of analysis of LOOH is based on the oxidation of ferrous to ferric ion and subsequent complexation of ferric ion by thiocyanate.1 The aim of this work was a reestimation of the oxidation of ferrous ion by hydroperoxide of oleic and linoleic acid to optimize the assay conditions with special attention given to the rate of oxidation of ferrous ion with alkyl hydroperoxide affected by acid type and its concentration, thus improving acceleration of the oxidation and the sensitivity of the method. Special attention was given to the measurements of very low LOOH concentrations from biological materials.2 The lowest detectable limit was estimated to be about 170 pmol LOOH/ml of analyzed solution, which corresponded to about 50 pmol LOOH/mg lipid in complex natural mixtures.

The susceptibility of natural fibers to biological damage is a serious problem in the protection of cultural heritage (CH) objects made of textile [1]. The treatment with ionizing radiation has been widely used for disinfestation and decontamination of CH artifacts and necessary doses established: up to 0.5 kGy for insect control, 4-10 kGy for fungi control, and 5-20 kGy for microbial decontamination. A number of wooden, paper, textile and leather items have been treated over the past 20 years at the 60Co gamma irradiation facility of the Ruđer Bošković Institute in Zagreb, Croatia [2]. Textile artifacts, mostly of ethnological significance, were efficiently disinfected by irradiation to less than 2 kGy dose. However, the application of higher doses for the control of fungi needs to be justified by investigating the effects of irradiation on textile fibers and to determine whether the treatment complies to the high standards of conservator specialists considering undesirable changes. The most common textile materials in CH artifacts - silk, cotton, linen and wool were chosen and model samples were γ-irradiated to D=120 kGy in contact with air. Such high dose ensures that all radiation effects are detected and could be later recognized in textiles samples irradiated to doses needed for fungi control. A lot on information on structural and chemical effects brought into a material on irradiation can be quickly determined assessing its thermal properties using DSC and TGA. DSC thermograms of irradiated model textile samples were monitored immediately on irradiation and after a 6-day postirradiation period and compared to those of unirradiated samples and of the same materials that were artificially aged. In spite of high dose the changes due to irradiation were comparable or lesser that those brought in by artificial ageing. Based on this results it can be proposed that radiation treatment is efficient and safe for fungi control of CH textile materials. [1] K. Kavkler, A. Demšar, Polym. Degrad. Stab. 97 (2012) 5, 786−792. [2] B. Katušin-Ražem, D. Ražem, M. Braun, Radiat. Phys. Chem. 78 (2009), 7/8 ; 729-731.

Moulds belonging to Aspergillus genus, mainly A. flavus, A. niger and A. parasiticus, are among the most important representatives that cause spoilage of food and feed products. The growth of fungi in foods or feeds is inhibited with application of different technological processes and various chemical additives. One of technologies that could prevent the growth of mould is radiation technology that uses ionizing radiation. This effective technology is widely used in food processes to destroy pathogenic and spoilage microorganisms without compromising the safety, nutritional properties and sensory quality of the food.

The interest in the study of lipid peroxidation processes in model systems has been motivated by aspects of the adverse consequences associated with peroxidation of unsaturated lipids in different natural and biological systems. In an attempt to elucidate the complex process responsible for lipid peroxidation in these systems, various simple model systems including those with surfactants were used. Surfactant supramolecules (micelles, vesicles, lyotropic mesophases) generally serve as models mimicking complex biological systems.1 An additional advantage of the surfactant supramolecules used as a model system is the possibility to investigate lipid peroxidation under acidic conditions. Low fatty acid solubility under acidic conditions can be bypassed by lipid solubilization into surfactant supramolecules using them as nanoreactors. We have chosen a nonionic surfactant, TWEEN®-20, whose stability and relative non-toxicity allows for its use as a suitable model system for biological media.2 This model system allows lipid reactivity to be studied in the context of the organization of the lipid molecules within the system, as well as their possible interactions with other types of molecules in their immediate vicinity, which can influence the lipid processes.3 A simple system with mixed nonionic surfactants TWEEN®-20/LA micelles as the model for the PUFA oxidation susceptibility assay, also as a very useful tool for studying thiyl radical-catalyzed cis-trans isomerization of unsaturated lipids will be described.

Biomimetic models provide basic molecular mechanisms studies that are closer to the biological environment such as living organism. There are two main classes of reactions that are known in the context of reactivity of polyunsaturated fatty acids toward free radicals. One of the well known process is lipid peroxidation and the second one is the process of geometrical isomerization of unsaturated lipids which can be catalysed by thiyl radicals (RS•). It has been shown that one process can be parallel with the occurence of the other and that lipid hydroperoxides and trans lipids can be the resulting effect of oxidative free radical conditions.1 Both processes have damaging effects on cell membranes of living organisms. In this study, the biomimetic model of micelles of linoleic acid containing 2-mercaptoethanol (RSH) were irradiated by gamma radiation under a variety of conditions where RS• are the main reactive species. The study of these processes has been extended in the presence of several natural occuring antioxidants which have shown their protective properties against lipid peroxidation and trans isomerization. Lipid peroxidation was retarded by ascorbic acid and α-tocopherol, whereas this process was strongly inhibited by resveratrol and the ascorbic acid/α-tocopherol mixture. Furthermore, antioxidants have a much stronger inhibitory effect on the peroxidation in the presence of 2-mercaptoethanol. Under anaerobic conditions, where lipid peroxidation is suppresed, the presence of antioxidants have influenced on a decrease of the trans isomerization level along the series resveratrol  -tocopherol  ascorbic acid. All results indicate that trans isomerization depends on the localization of the particular antioxidant in model system. In order to protect lipid structures from the thiyl radical damage a new role of the essential antioxidants can be assessed.

Resveratrol (trans-3, 4', 5-trihidroksistilben, ArOH), prirodni antioksidans kojeg najviše ima u crnom grožđu i vinu, zadnjih je godina intenzivno istraživan zbog svojih značajnih bioloških aktivnosti. Nedostatak proučavanja antioksidativnog mehanizma resveratrola ukazuje na potrebu za dodatnim istraživanjima koja bi dovela do boljeg razumijevanja njegovih bioloških svojstava. U tu svrhu korištenjem vremenski razlučenih tehnika laserske pulsne fotolize i pulsne radiolize su ispitana fotofizička i fotokemijska svojstva resveratrola, te identificirani i okarakterizirani njegovi intermedijeri, radikal kation resveratrola (ArOH● +) i fenoksil radikal resveratrola (ArO●). Apsorpcijski spektar ArOH●+ u acetonitrilu (ACN) s maksimumom apsorpcije pri 500 nm dobiven je rezonantnom dvofotonskom ionizacijom pulsom od 355 nm ili 266 nm proizvedenim pomoću Nd:YAG lasera s energijama od 50 mJ, odnosno 15 mJ. Određen je apsorpcijski koeficijent ArOH●+, ε(500 nm, ACN) = 33 400 mol-1 dm3 cm-1. Na osnovu kinetičkih rezultata pokazano je da je konstanta brzine nestajanja ArOH●+ pri 500 nm jednaka konstanti brzine nastajanja ArO● pri 390 nm, i iznosi k = 2, 7 x 105 s-1. U vodi ArOH●+ nije detektiran zbog vrlo brze deprotonacije, već je detektiran samo ArO● pri 410 nm. Dodatkom 0, 25–1, 5% H2O u ACN određena je konstanta brzine deprotonacije ArOH●+ u ArO●, koja iznosi 1.3 x 108 mol-1 dm3 s-1. Korištenjem obiju tehnika određeni su apsorpcijski koeficijenti ArO●, ε(390 nm, ACN) = 15 200 mol-1 dm3 cm-1 i ε(410 nm, H2O) = 14 600 mol-1 dm3 s-1.

Utvrđeno je da se u anaerobnim uvjetima u micelarnoj otopini LH u prisustvu tiola odvijala samo cis-trans izomerizacija, mehanizmom adicije/eliminacije tiilnog radikala na dvostrukoj vezi LH, te je katalitički ciklus iznosio 420. U otopinama LH u ravnoteži sa zrakom utvrđeno je da se cis-trans izomerizacija još uvijek odvija s katalitičkim ciklusom 370, uz značajnu koncentraciju proizvedenih hidroperoksida LH. U ovom radu prikazat ćemo i utjecaj veličine micela LH na pojavu istraživanih procesa. Rezultati su pokazali da postoji razlika u raspodjeli nastalih mono trans izomera čime je potvrđeno postojanje supramolekulske organizacije u ispitivanom modelnom micelarnom sustavu.

The modeling of free radical reactions under naturally occurring conditions has become a basic step in the research of fundamental mechanisms of biological processes. The far most known process regarding polyunsaturated fatty acids (PUFA) is the peroxidation process which is generally considered to be the major mechanism of cell injury in organisms subject to oxidative stress. A much recent research deals with the geometrical isomerization of PUFA, evidencing that the cis double bond configuration is a inherent characteristic of membrane lipids which can be altered by radical stress. In view of the fact that these processes in lipids are the most relevant chemical processes occurring to PUFA, it is very useful to perform model studies where both processes occur. We have established the simplest biomimetic model of cell membrane, the micelles of linoleic acid (LH), prepared by addition of a non-ionic surfactant (TWEEN®-20) and the resulting solutions were irradiated by ionizing radiation up to 400 Gy under a variety of conditions where thiyl radicals are the main reactive species. The irradiation-induced peroxidation and trans isomerization in our model systems under controlled oxidation conditions have been studied. The concentrations of hydroperoxide of linoleic acid (LOOH) were determined using the spectrophotometric ferric thiocyanate method, while geometrical isomers were analyzed by GC using known conditions for the separation of cis and trans isomers. Data on relative importance of these processes in this competitive environment have been considered. This lecture will demonstrate that hydroperoxy- and trans-PUFA can be the resulting effect of oxidative free radical conditions. While under anaerobic conditions only the cis-trans isomerization was observed, in air-equilibrated solutions a substantial amount of LOOH was produced and the cis-trans isomerization process was still observed, e.g., irradiation of 500 M of LH at 400 Gy and dose rate of 4.6 Gy/s gave 20 M of LOOH and 10% conversion of LH into mono-trans isomers. The effect of micelle size will be discussed in order to gather data on the effect of supramolecular organization for the outcome of the two processes, and in particular, to envisage any positional preference of the two double bond.

Rezveratrol (trans-3, 5, 4'-trihidroksistilben) je polifenol iz skupine stilbena prisutan ponajviše u grožđu i grejpu. Poznato je da je rezveratrol dobar hvatač slobodnih radikala te je stoga djelotvoran antioksidans [1]. Dok su antioksidativna svojstva rezveratrola u modelnim i biološkim sustavima zadnjih godina intenzivno istraživana, u literaturi pronalazimo vrlo malo kinetičkih podataka za reakcije rezveratrola s organskim slobodnim radikalima, napose s alkoksilnim odnosno tiilnim radikalima. Poznato je da alkoksilni radikali iniciraju niz lančanih reakcija abstrakcijom vodikovog atoma, dok tiilni radikali uz svoja svojstva dobrih hvatača slobodnih radikala iniciraju i trans izomerizaciju dvostrukih veza u nezasićenim masnim kiselinama [2]. Da bi se pratila kinetika istraživanih reakcija korištena je metoda laserske pulsne fotolize kojom su pomoću Nd:Yag lasera na 355 nm, odnosno rubinskog lasera na 347 nm proizvedeni terc-butoksilni odnosno tiilni radikali na mikrosekundnoj vremenskoj skali. Terc-butoksilni radikali proizvedeni su direktno fotolizom di-terc-butil-peroksida u acetonitrilu [3], a tiilni radikali indirektno u otopini tiola i fotosenzibilizatora, benzofenona u acetonitrilu. U ovom radu bit će prikazane konstante brzina navedenih reakcija koje su određene u uvjetima pseudo-prvog reda. Konstante brzina reakcija rezveratrola i terc-butoksilnih odnosno tiilnih radikala bit će uspoređene sa konstantama brzina reakcija rezveratrola s OH●, N3●, CCl3OO● radikalima, dobivenim pulsnom radiolizom [1]. Iz apsorpcijskog spektra svih laserskim pulsom generiranih kratkoživućih intermedijera čija se kinetika pratila, identificirani su pojedinačni spektri prisutnih apsorbirajućih čestica i određene njihove koncentracije u funkciji vremena pomoću posebnog programa za dekonvoluciju i referentnih apsorpcijskih spektara pojedinačnih čestica poznatih iz literature.

Sudionicima Seminara pokazan je uređaj za ozračivanje u Laboratoriju za radijacijsku kemiju i dozimetriju Instituta Ruđer Bošković. Objašnjen je rad uređaja i navedeni primjeri njegove upotrebe u zaštiti predmeta kulturne baštine.

Radical-mediated oxidation products of lipids have been studied for many years though the use of the products of these reactions as specific markers of oxidative damage in vivo has been developed only in the past decade. The greatest needs in this field of research has been to develop relible methods for the quantitative measurement of oxidative products. One of these products are detrimental lipid hydroperoxides (LOOH) which are well known to initiate further autoxidations during reactions of their production and decomposition. Quantitative analysis of LOOH have been in a demand as a consequence in an effort to provide the method for determination of LOOH. The spectrophotometric method of analysis of LOOH was based on the oxidation of ferrous to ferric ion and subsequent complexation of ferric ion by thiocyanate. The aim of this work was a reestimation of the oxidation of ferrous ion by hydroperoxide of oleic and linoleic acid to optimize the assay conditions with special attention given to the rate of oxidation of ferrous ion with alkyl hydroperoxide of different structure, thus improving acceleration of the oxidation and the sensitivity of the method.

U radu je dat prikaz stanja u vinogradarsko vinarskoj djelatnosti. Temeljem analize postojećeg stanja predlažu se smjernice razvoja ; svrhovito pristupiti programima razvoja rasadničarstva, čuvanju cjelovitosti tradicionalnih proizvodnih prostora, osvajanju novih proizvodnjih cjelina uz razumno korištenje suvremenih tehnoloških rješenja, reviziji zaštite zemljopisnog podrijetla vina, kao i razvoju programa ciljanog obrazovanja mladih ljudi te programa cjeloživotnog obrazovanja.

Plant derived resveratrol (trans-3, 5, 4'-trihydroxystilbene) possesses a broad spectrum of biological activities, one of them are very well known its antioxidative properties [1]. Our work aims to provide kinetic data with regard to the reactivity of resveratrol with uninvestigated short-lived bioradicals, identified as mediators in oxidative lipid degradation processes. Radicals of our interest are alkoxyl radicals, well known propagators of the chain free radical reactions in lipids, and thiyl radicals which protect lipids from their degradation pathway, but at the same time cause the isomerization of the double bonds. In order to investigate these reactions of resveratrol laser flash photolysis was used. On the basis of competitive kinetics the rate constants were determined under pseudo-first order conditions in acetonitrile solutions at room temperature. Thiyl radicals were generated indirectly in solution containing 1-octadecanthiol and photosensitive benzophenone in acetonitrile using the light pulses at 347 nm from ruby laser. Tert-butoxyl radicals were generated directly by peroxide bond cleavage from di-tert-butyl peroxide in acetonitrile by light pulses of Nd:YAG at 355 nm [2], and ruby at 347 nm [3]. Obtained rate constants for the reactions of resveratrol and radicals generated by laser flash photolysis will be summarized and compared with rare literature data for the rate constants of investigated reactions of resveratrol and other radicals generated by pulse radiolysis.

Alkoxyl radicals are important intermediates in processes of lipid peroxidation that react with many biologically relevant material exerting damage in cells. These radicals are readily formed from hydroperoxides in the presence of reduced transition metal ions. Because reaction of alkoxyl radicals plays an important role in many autoxidation processes, we decided to measure its kinetics. Tert-butoxyl radicals (t-BuO•) were generated by homolytic photodecomposition of di-tert-butylperoxide using ruby laser flashes at 347 nm. The reaction of t-BuO• radicals with Fe2+ was studied under pseudo-first order conditions. The quantum yield of iron(III) was determined by measuring the absorbance of Fe3+ ion as (FeCl)2+ complex at 360 nm 2 us after the flash. The influence of the medium acidity on the rate constant was considered. All results will be summarized and discussed in terms of the stability of t-BuO• radical at different acidity and polarity of the medium.

Lipid peroxidation is generally considered to be the major mechanism of cell injury in organisms subject to oxidative stress. Many medical aspects of cellular damage related peroxidation of unsaturated lipids have motivated the interest in studies on the lipid peroxidation processes in model membrane systems such as micelles and vesicles. Lipid micelles are structurally much simpler than bilayers of phospholipids, thus fatty acids provide reasonable model compounds susceptible to undergo processes associated with oxidative modifications of lipids. Thiols and other sulfur compounds play an important role in the protection of lipids from their degradation pathways by scavenging the primary oxidizing species or by repairing molecules damaged by their reactions. However, oxidation of polyunsaturated fatty acids (PUFA) by thiyl radicals from thiols is believed to be responsible for some of the biological damage resulting from lipid oxidation. At the same time, thiyl radicals can cause the isomerization of the PUFA double bonds with the formation of trans isomers. In this study, radiation-induced peroxidation of PUFA was investigated in mixed micelles formed from nonionic surfactant (Tween 20) and PUFA under conditions of higher acidity, in the absence and in the presence of 2-mercaptoethanol. We measured the formation of hydroperoxides of PUFA in micelles, exposed to radicals generated by gamma radiation from thiol. The geometrical isomerization of PUFA was simultaneously analyzed by gas chromatography. The effects of dose and dose rate on both lipid modification processes were studied. The results suggest that lower dose rates were more efficient in producing lipid hydroperoxidation and isomerization, respectively. The dose rate dependence of peroxidation found in our model system indicated the validity of the inverse square-root relationship with dose rate. The support and sponsorship by COST Action CM0603 on “Free Radicals in Chemical Biology (CHEMBIORADICAL) are kindly acknowledged.

The methods available to detect lipid peroxidation vary considerably in their specificity, and indeed, it is often useful to have a method that will measure a broad range of products to give a general status of lipid peroxidation. Other methods are highly specific for individual products, which in turn can provide useful information about mechanisms and types of damage. The oxidation of ferrous ion with lipid hydroperoxides was the base for the sensitive quantitative spectrophotometric method for lipid hydroperoxides determination evaluated by us. The method could be very well applicable to different interdisciplinary studies of peroxidation of lipids or the oxidative stress status.

The far most known process regarding polyunsaturated fatty acids (PUFA) is the peroxidation process which is generally considered to be the major mechanism of cell injury in organisms subject to oxidative stress. A much recent research deals with the geometrical isomerization of PUFA, evidencing that the cis double bond configuration is a inherent characteristic of membrane lipids which can be altered by radical stress. In view of the fact that these processes in lipids are the most relevant chemical processes occurring to PUFAs, it is very useful to perform model studies where both processes occur. Lipid reactivity can be addressed by biomimetic chemistry. We have established the simplest biomimetic model of cell membrane, the mixed nonionic/anionic surfactant micelles of linoleic acid. The irradiation-induced peroxidation and trans isomerization in our model systems under controlled oxidation conditions have been studied. Data on relative importance of these processes in this competitive environment have been considered. This lecture will demonstrate that hydroperoxy- and trans-PUFA can be the resulting effect of oxidative free radical conditions.

Alkoxyl radicals are important intermediates in processes of lipid peroxidation that react with many biologically relevant material (i.e. aminoacids, peptides, proteins) exerting damage in cells. These radicals are readily formed from hydroperoxides in the presence of reduced transition metal ions. Because reaction of alkoxyl radicals plays an important role in many autoxidation processes, we decided to measure its kinetics. Tert-butoxyl radicals (t-BuO•) were generated by homolytic photodecomposition of di-tert-butylperoxide using ruby laser flashes at 347 nm. The reaction of t-BuO• radicals with Fe2+ was studied under pseudo-first order conditions. The influence of the medium acidity on the rate constant was considered. All results will be summarized and discussed in terms of the stability of t-BuO• radical at different acidity and polarity of the medium.

Lipid peroxidation is generally considered to be the major mechanism of cell injury in organisms subject to oxidative stress. Many medical aspects of cellular damage related peroxidation of unsaturated lipids have motivated the interest in studies on the lipid peroxidation processes in model membrane systems such as micelles and vesicles. Lipid micelles are structurally much simpler than bilayers of phospholipids, thus fatty acids provide reasonable model compounds susceptible to undergo processes associated with oxidative modifications of lipids. Thiols and other sulfur compounds play an important role in the protection of lipids from their degradation pathways by scavenging the primary oxidizing species or by repairing molecules damaged by their reactions. However, oxidation of polyunsaturated fatty acids (PUFA) by thiyl radicals from thiols is believed to be responsible for some of the biological damage resulting from lipid oxidation. At the same time, thiyl radicals can cause the isomerization of the PUFA double bonds with the formation of trans isomers. In this study, radiation-induced peroxidation of PUFA was investigated in mixed micelles formed from nonionic surfactant (Tween 20) and PUFA under conditions of higher acidity, in the absence and in the presence of 2-mercaptoethanol. We measured the formation of hydroperoxides of PUFA in micelles, exposed to radicals generated by gamma radiation from thiol. The geometrical isomerization of PUFA was simultaneously analyzed by gas chromatography. The effects of dose and dose rate on both lipid modification processes were studied. The results suggest that lower dose rates were more efficient in producing lipid hydroperoxidation and isomerization, respectively. The dose rate dependence of peroxidation found in our model system indicated the validity of the inverse square-root relationship with dose rate. The support and sponsorship by COST Action CM0603 on “Free Radicals in Chemical Biology (CHEMBIORADICAL) are kindly acknowledged.

Atlas je jedinstveno djelo koje na originalan način prikazuje razvoj vinogradarstva i vinarstva na prostorima Hrvatske. Vodi nas kroz povijesne mijene i prikazuje etnografske posebnosti života i rada s vinogradom i vinom naših krajeva. Upoznaje nas sa sortimentima važnijih podloga za vinovu lozu te vinskim i stolnim sortama. Vodi nas regionalnim putovima hrvatskih vinogradarskih prostora, prikazujući geološke, pedološke i druge okolinske uvjete uzgoja loze u kontinentalnoj i primorskoj Hrvatskoj. Prikazana je također i biologija loze s karakterističnim fiziološkim mijenama, tehnološke specifičnosti osnivanja i uzdržavanja vinograda, proizvodnje grožđa i loznog sadnog materijala. Prikazuju se i postupci primarne prerade grožđa, dorade i njege bijelih, ružičastih i crvenih vina standardne i predikatne kakvoće. Obrađeni su i hrvatskih narodni običaji ugrađeni u tradiciju življenja čovjeka u svom okružju.

Poznato je da su procesi peroksidacije lipida koji teku reakcijama slobodnih radikala, jedan od glavnih mehanizama nastajanja brojnih patoloških stanja i oštećenja u stanicama organizama izloženih oksidacijskom stresu. Spojevi tiola su dobri donori vodika, te kao djelotvorni hvatači slobodnih radikala imaju važnu ulogu u usporavanju procesa lipidne peroksidacije. Istovremeno, radikali tiola nastali tijekom oksidacijskog stresa mogu uzrokovati izomerizaciju dvostruke veze u polinezasićenim masnim kiselinama (PUFA) stvarajući geometrijske trans izomere. Za razliku od cis izomera koji su zastupljeni u prirodi, trans izomeri PUFA posjeduju specifična strukturalna i kemijska svojstva koja se neposredno odražavaju na svojstva biomembrana nepovoljna za njeno funkcioniranje. U dosadašnjim istraživanjima djelotvornost radikala tiola u procesu izomerizacije lipida proučavana je u modelnim sustavima liposoma, kao i u stanicama i tkivima živih organizama [1]. Svrha našeg rada je istraživanje modifikacije PUFA inducirane slobodnim radikalima u jednostavnim modelnim micelarnim sustavima. Prikazat će se rezultati modifikacije PUFA u prisustvu radikala tiola, te će biti uspoređeni s rezultatima peroksidacije inducirane u oksidacijskim uvjetima izomerizacije. Istraživanja su provedena u razrađenim micelarnim sustavima u kojima su se spomenuti procesi u prisutnosti β -merkaptoetanola pratili nakon induciranja γ -zračenjem dozom do 100 Gy, u ravnoteži sa zrakom, odnosno u uvjetima bez dostupnosti kisika. Za analizu izomera esterificiranih PUFA upotrebljena je plinska kromatografija [1], dok je za određivanje stupnja peroksidacije odnosno kvantitativno određivanje hidroperoksida PUFA korištena spektrofotometrijska feritiocijanatna metoda [2]. Rezultati u uvjetima smanjene koncentracije kisika u micelarnim otopinama linolne kiseline (LiH) pokazali su da nastajanje hidroperoksida LiH, iako mikromolarnih koncentracija, ovisi o dozi zračenja. Pritom je inducirana izomerizacija, te se volumni udio trans izomera povećavao s dozom zračenja do 20%. U prisustvu kisika značajno je inducirano nastajanje hidroperoksida, ali pritom nije opaženo nastajanje trans izomera. U ovom radu bit će predložen mehanizam izomerizacije micelarnih sustava PUFA u oksidativnim uvjetima, u usporedbi s mehanizmom izomerizacije PUFA inducirane radikalima tiola u pravim otopinama PUFA. Ovaj rad je obavljen u okviru suradnje u COST Akciji (CM0603): Free Radicals in Chemical Biology.

In Croatia, viticulture is important economic branch, even thou in some of its fields there is no alternative. Therefore, setting up the quality management system into production environment of this economic branch is imperative in the Republic of Croatia. The aim of this work is to demonstrate methodology of establishment of vineyard cadastre in Croatia. Vineyard cadastre is record about real and potential vineyards areas. Establishment and incorporation of vineyard cadastre is obligation defined by Wine Act (Official Gazette 96/03) and also with EU acquis. For setting up of vineyard cadastre, digital ortophotographs, vectors cadastral plans, relief digital model, digital pedological maps as sources are used as well as register of grape, wine and fruit wine producers. From above sources, all important data are gained, and on the basis of them, surveillance, monitoring and planning all activities in viticulture and wine production are done. Interpretation and analysis of mentioned sources is carried by using the GIS technology.

During oxidative stress reactive oxygen species and peroxyl radicals of lipids can be scavenged by good hydrogen donors such as thiols, leading to interrupting the cascade of the lipid peroxidation process. Therefore thiols are considered to be effective protectors for the lipid degradation under oxidative conditions. On the other side, thiyl radicals generated from thiols by free radicals cause the isomerization of the double bonds, with the formation of geometrical lipid trans isomers.The general objective of this work was a comparative study of the behaviour of unsaturated fatty acid in the presence of thiols. Primary radicals were generated by γ -irradiation of a model lipid system containing linoleic acid (LiH), nonionic surfactant (Tween 20) and 2-mercaptoethanol at pH 5. After γ -irradiation of the model systems up to 400 Gy and in the presence of oxygen, high concentration of LiOOH (1 × 10– 4 mol dm-3) was determined, while the amount of trans LiH methyl ester simultaneously formed under the same conditions was very low (~ 10 %). However, in the absence of oxygen the effective inhibition of propagation of lipid peroxidation with subsequent increasing of the isomerization processes was observed. It was found that the amount of trans isomers increased with increasing of the irradiation dose. The effect of the dose rate on the lipid modification processes was also investigated.

U modelnim sustavima lipida prikladnim za proučavanje lipidne peroksidacije najčešće se koriste prijelazni metali kao djelotvorni inicijatori ovih biološko važnih procesa, koji u organizmu teku reakcijama slobodnih radikala dovodeći ga u stanje oksidacijskog stresa. Dok mehanizmi procesa induciranih prijelaznim metalima još uvijek nisu u potpunosti poznati, pouzdano se zna da željezo ima važnu ulogu kako u pojavi tako i u brzini induciranja i/ili kataliziranja lipidne peroksidacije ovisno o uvjetima reakcijske sredine (pH, utjecaji kelata, prisustvo drugih oksidansa) [1]. U dosadašnjim istraživanjima promicanja peroksidacije lipida, s dodatkom željezovih soli biološkim sustavima istovremeno su generirane sve vrste radikala nastale reakcijama autoksidacije željezovog(II) iona s jedne strane, te radikala lipida nastalih željezom-induciranom katalitičkom razgradnjom hidroperoksida inherentnih lipidnom sistemu, s druge strane. Ovime je proučavanje i razumijevanje mehanizama peroksidacije otežano, napose selektivnog proučavanja faza procesa peroksidacije. Svrha ovog rada je pronaći uvjete pogodne za selektivno istraživanje faze propagacije peroksidacije u jednostavnom modelnom sustavu s nezasićenom masnom kiselinom u vodi. Budući se tumori i upalni procesi razvijaju kod vrlo niskih pH, poseban interes je istražiti lipidnu peroksidaciju u modelnom sustavu u uvjetima sredine veće kiselosti. Modelni micelarni sustav nezasićenih masnih kiselina ustanovljen je pomoću linolne kiseline, a koristila se neionska površinski aktivna tvar Tween 20. U svrhu karakterizacije nastalih miješanih micela korištena je dinamička metoda raspršenja svjetlosti. Procesi željezom-inducirane oksidacije nezasićenih masnih kiselina praćeni su kod vrijednosti od pH 2.5 do pH 8.0, a korištene su spektrofotometrijske metode UV-dienske konjugacije i feritiocijanatne metode [2]. U ovom radu bit će prikazani rezultati koji pokazuju da je opisani modelni sustav pogodan za proučavanje propagacije peroksidacije nezasićenih masnih kiselina u uvjetima pH koji se razlikuju od onih fizioloških, pH << 7.4, s naglaskom na utjecaj strukture nezasićenih masnih kiselina na podložnost oksidaciji.

Lipid hydroperoxides (LOOH) present even in traces, easily degrade under effects of different initiators including transition metals. In previous lipid peroxidation investigations, the ferrous addition to lipid systems caused the simultaneous production of hydroxyl and alkoxyl radicals, leading to the propagation of lipid oxidation process. Consequently, the individual steps in lipid peroxidation could not be distinguished. This was the reason for rather difficult interpretations and disagreements between the molecular mechanisms proposed for the different phases of peroxidation. We have established the simple model system which allows the selective study of the propagation of lipid peroxidation. Mixed micelles formed from nonionic surfactant (Tween 20) and polyunsaturated fatty acids (PUFA) have been used as a model system in which autoxidation of ferrous ions and thereby reactive oxygen species generation does not occur. Various subsystems were analyzed in order to better understand the involved processes. Decreasing pH makes iron(II) and iron(III) ions more available for oxidative processes. With exception of the normal tissue of the gastric system having ordinary high acidity, in comparison with normal tissue, tumors have relatively low pH levels. Thus, it is important to consider the mechanism of LH oxidation under conditions other than normal physiological ones. Under optimum experimental conditions, oxidative susceptibility of different PUFA under influence of ferrous ion, with a special attention given to the oxidation rate as affected by the ferrous concentration, will be determined. It was found that the oxidative stability of PUFA decreases with increasing number of double bonds or number of bis-alylic position. The susceptibility of PUFA to peroxidation in aqueous micellar solution could be associated with their individual conformations. Dependence of linoleic acid peroxidation on ferrous concentrations revealed that chosen model allow study of either the propagation or the termination phase of lipid peroxidation.

Anticorrosion polyolefinic films are being increasingly used in corrosion protection, from packaging of electronic products to protection of firearms of all sizes. Anticorrosion polymer films are produced by coextrusion of polymer and vapor phase corrosion inhibitor (VCI) that slowly diffuses out of the film and forms a protective layer on metal surface. Thereby the concentration of VCI in the film decreases with time what limits duration of anticorrosion protection. Earlier [1] we analyzed a number of such films of various ages, identified polymer carrier as low-density polyethylene and VCI as an organomolybdate salt. We also confirmed that VCI provides protection by migrating out of the film. We determined that the protection last up to 6 or 7 years, depending on initial concentration of VCI in the film. Particle Induced X-Ray Emission spectroscopy, an ion-beam analysis method was necessary both to confirm the nature of VCI and determine its concentration in anticorrosion films. The concentration of molybdenum in the films is very low so the error of classical analytical methods would be greater than the expected concentration change or even concentration itself. In PIXE the X-ray emission characteristic of a particular nuclei produced by, in this case proton impact on a material, is measured so it is possible to identify the nuclei present in the film if corresponding atomic number is higher than 12 and to determine its concentration in the sample if larger than 1 ppm. The drawback of PIXE method is its limited availability. Because of that, a method that provides fast and reliable determination of VCI concentration change with time to detect when the anticorrosion protection ends was needed. Since UV-VIS spectrophotometers are much more widespread, the goal of this investigation was to determine whether there is a correlation between the concentration of Mo determined by PIXE and UV-VIS absorptions in anticorrosion films. The assumption that the anticorrosion films are of same thickness was checked by FTIR. The UV-VIS spectra of selected anticorrosion films with various concentration of VCI were recorded showing two prominent absorptions at about 710 and 610 nm. In spite of the problems of determination of the molar absorptivities of the VCI, the intensities of both absorptions had excellent correlation to molybdenum concentrations determined by PIXE so it was concluded that UV-VIS spectroscopy could be used to control the decrease of VCI concentration. In that manner control of the properties of anti-corrosion films is possible provided initial concentration of VCI is determined by another method that gives absolute concentration of VCI in the sample. [1] Pucić, I. ; Madžar, T. ; Jakšić, M. Chem. Monthly. 137 (2006), 953-961.

The small pool of non-bound ferrous iron in cells is known to provide one of the active species involved in probably the most important route for free radical formation leading to increased levels of lipid peroxidation. One of the pathways for excessive production of free radicals is decomposition of hydroperoxides of unsaturated fatty acids catalyzed by iron. Ferrous ions-chelate ligand systems in the presence of LOOH serve as models to establish the reactions that result in the formation of reactive oxyradicals. Rate constants of these reactions are essential to determine which reaction will dominate under selected conditions. However, the literature is scarce and inconsistent with regard to the oxidation of Fe2+ with LOOH in the absence of macromolecular ligands or in the presence of simple unidentate ligands. All potentially occurring subsequent radical reactions are much faster than the rate of the reaction. Thus, the overall reaction rate should be determined only by this reaction. The aim of this work was determination of the overall rate constants of oxidation of Fe2+ with various LOOH and with several non-lipidic hydroperoxides in CH2Cl2:CH3OH solvent mixture at 8 × 10–4 mol dm–3 HCl. The course of the reactions was followed by spectrophotometric determination of ferric ion complexed with thiocyanate. Stoichiometry and the rate constant of the oxidation of Fe2+ with ROOH depended on their structure. The average second-order rate constant of the oxidation of Fe2+ with tertiary ROOH was 250 ± 40 M-1 s-1, while with secondary lipid LOOH was 1390 ± 340 M-1 s-1 ; the rate constants of the oxidation of Fe2+ with LOOH from different biological materials were in the same range. There was no difference between activation enthalpies of geometrical isomers, methyl esters of OlH, and the rate constant of saturated fatty acid hydroperoxides (CeOOH) was very comparable with others. However, discreet differences among the rate constants of the oxidation of Fe2+ with mono- (920 ± 160 M-1 s-1) and poly-unsaturated fatty acids (1420 ± 90 M-1 s-1) were observed. The activation energies for these reactions average 30 kJ mol-1, the value which was relatively small. All these values obtained were comparable. The small activation enthalpy of 28.5 kJ mol–1 indicated the entropy controlled reaction. We assume that the oxidation proceeds by an inner-sphere mechanism considering that the breakdown of the successor inner-sphere complex forming reactive alkoxyl radicals probably is the rate-limiting step.

The iron-mediated lipid peroxidation has been evaluated by focusing the investigations in two directions: (a) measuring the concentrations of oxidation products of lipids, and (b) investigation based on evaluation of susceptibility of lipids to oxidation upon their exposure to a source of free radicals. With the main aim to develop a reliable quantitative method for the measurement of peroxidation for in lipidic material, we produced a method of analysis, which has appeared applicable to different interdisciplinary studies of peroxidation of lipids. We have studied peroxidation of unsaturated fatty acids (LH) catalyzed by ferrous ions in buffering condition where autoxidation of Fe2+ and hydroxyl radicals generation does not occur. In these conditions, Fe2+ is oxidized only with preformed hydroperoxides of unsaturated fatty acids (LOOH) to form radical propagators, alkoxyl- and peroxyl- radicals. It is important to consider this process under conditions other than normal physiological ones since, in comparison with normal tissue ; tumors have relatively low pH levels. The lipid peroxidation was followed by determination of concentrations of LOOH by measurements of UV-diene conjugation and by the ferric thiocyanate method.

U cilju pronalaženja optimalnih eksperimentalnih uvjeta za selektivno istraživanje faze propagacije lipidne peroksidacije istraživana je peroksidacija nezasićenih masnih kiselina (LH) katalizirana ionima željeza(II). U ovom radu korišteni su modelni sustavi LH u kojima se ne odvija autooksidacija željeza(II) i time generiranje reaktivnih čestica kisika. U pronađenim uvjetima oksidacija željeza(II) odvija se samo s početno stvorenim hidroperoksidima nezasićenih masnih kiselina (LOOH) stvarajući alkoksil- i peroksil-radikale, propagatore lipidne peroksidacije. Peroksidacija LH pratila se određivanjem koncentracije LOOH metodom UV-dienske konjugacije, odnosno feritiocijanatnom metodom, s posebnim osvrtom na razradu metoda u cilju postizanja kvantitativnosti u primjenjenim uvjetima.

The general objective of our part of the project would be to improve the understanding and detection of lipid peroxidation processes in simple model systems. The planned investigations of the kinetics and mechanisms of short-lived reactive species shall be extended to the study of biologically important molecules and processes whereby chemically reactive free radicals could be produced under controlled conditions. Since iron is one of the biological dominant transition metals, understanding of iron chemistry in different media is very important. The most common cause of lipid oxidation is the interaction between transition metals originating in the aqueous phase and lipid hydroperoxides located at the interface in lipid model systems (micelles). Information obtained in these systems may be applicable to the elucidation of the processes occurring in more complex biological media. The rate of various chemical reactions may be changed in micellar media due to the two most important factors, hydrophobic and/or electrostatic interactions of the surface of aggregates with reactive species in the aqueous phase. Further studies on the influence of interface characteristics on the oxidizability of polyunsaturated fatty acids in aqueous model systems could lead to better understanding of their oxidative stability as compared with the bulk phase or in solution. By measuring the kinetics of reactive species and concentrations of stable products formed we hope to contribute to: (a) the understanding of mechanisms of reactions of transition metals in different model media, with special attention given to reactions of iron with biologically important molecules and the formation and the reactions of free radicals ; (b) the improvement of the existing methods for the detection and quantitation of lipid peroxidation products.

Antikorozijske polimerne folije, koje se proizvode koekstruzijom polimera i isparivog inhibitora korozije (vapor phase corrosion inhibitor, VCI), široko se upotrebljavaju za zaštitu različitih predmeta. Prethodno [1] smo analizirali folije različite starosti, odredili da je polimerni nosač polietilen niske gustoće a da je VCI organomolibdatna sol. Također smo potvrdili da VCI štiti tako da migrira iz folije što dovodi do smanjenja njegove koncentracije u foliji i ograničava trajanje antikorozijske zaštite koja traje 6-7 godina, ovisno o početnoj koncentraciji VCI u foliji. Opisano identificiranje i određivanje koncentracije VCI provedeno je PIXE (particle induced X-Ray emission) spektroskopijom, mjerenjem intenziteta karakterističnog X-zračenja koje atomi uzorka emitiraju nakon bombardiranja protonima. Nedostatak te metode je njena ograničena dostupnost. Zbog toga je trebalo pronaći metodu koja omogućava brzo i pouzdano određivanje promjene koncentracije VCI s vremenom kako bi se moglo utvrditi kada prestaje antikorozijska zaštita. Oblik uzorka i niska koncentracija VCI u njemu onemogućavali su korištenje uobičajenih metoda određivanja koncentracije molibdena. Kako su UV-VIS spektrofotometri mnogo dostupniji, cilj ovog istraživanja bio je da se utvrdi postoji li korelacija između PIXE intenziteta i UV-VIS apsorpcija antikorozijsih folija. Snimljeni su UV-VIS spektri odabranih antikorozijsih folija s različitom koncentracijom VCI koji su pokazali dvije izrazite apsorpcije pri oko 710 i 610 nm. Korelacija između intenziteta apsorpcija pri 710 nm i koncentracija molibdena određenih PIXE spektroskopijom bila je vrlo visoka pa je zaključeno da se UV-VIS spektroskopija može uspješno koristiti za praćenje promjene koncentracije VCI. Time se ostvaruje kontrola svojstava antikorozijski filmova pod uvjetom da se prethodno odredi početna koncentracija molibdena metodom koja daje apsolutnu koncentraciju u uzorku. [1] Pucić, Irina ; Madžar, T. ; Jakšić, Milko. PIXE spectroscopy for determination of volatile corrosion inhibitor concentration in anticorrosion polymer films. // Monatshefte fuer Chemie. 137 (2006), (7) ; 953-961.

Radiation-induced chemical changes in foods are generally very small at the usual processing doses. Nevertheless, a sensitive and reproducible spectrophotometric method of lipid hydroperoxides (LOOH) determination based on the formation of feric thiocyanate, as modified in our laboratory1, could be applied for positive identification of irradiation treatment2. The representatives of various classes of lipid containing foods: egg and milk powder, soya flour and haselnuts were investigated3. The decay of radiation-induced LOOH in irradiated egg powder could be described by dispersive kinetics. After a six months’ storage it was still possible to unambigously identify LOOH in samples irradiated with the processing dose of 2 kGy2, 3. The level of LOOH attained by that time was still above the average level of indigeneous LOOH in unirradiated commercial egg samples, supplied by two producers (0.110 &plusmn ; 0.08 mmol/kgL). Another prominent feature of radiation peroxidation of egg powder has been shown to be suitable for the identification purpose – the inhibition dose, Dinh. Irradiation of egg powder in the presence of air revealed an initially slow increase of LOOH with dose, caused by an inherent antioxidative capacity, followed by a faster linear increase after the breakpoint inhibition dose. Dinh did not depend on dose rate spanning three orders of magnitude (about 4, 0.4 and 0.04 Gy/s). In the commercial samples the value of Dinh = 2.2 &plusmn ; 0.8 kGy was obtained. One would expect almost complete destruction of antioxidative properties of egg powder when treatment dose was equal to or exeeded the inhibition dose. However, the reirradiation of samples which had been originaly irradiated with 2 kGy and kept in dark at room temp. revealed a reduced Dinh = 1.0 &plusmn ; 0.1 kGy. In samples irradiated with 4 kGy and kept under the same conditions, the reduction of Dinh to 0.5 kGy occurred on by reirradiation. Besides identification, this offers a possibillity for the estimation of the original irradiation dose. 1. 1. B. Mihaljević, B. Katušin-Ražem, D. Ražem: Free Radic. Biol. Med., 21 (1996) 53-63. 2. B. Katušin-Ražem, B. Mihaljević, D. Ražem: Nature, 345 (1990) 584. 3. B. Katušin-Ražem, B. Mihaljević and D. Ražem: Detection of irradiation treatment of foods based on lipid hydroperoxidation, submitted.

Anticorrosion films, produced by coextrusion of polymer and vapour phase corrosion inhibitor (VCI) that provides protection by migrating out of the film and forming a layer on a metallic surface covered by it, are being increasingly used in corrosion protection. This investigation had several goals: - to identify the polymer carrier and the VCI of a particular set of anticorrosion films, - to confirm migration of VCI and determine how long the films provide protection, - since the VCI was identified as an organomolybdate salt, to determine its concentration using UV-VIS spectroscopy. The polymer carriers of analysed films of various ages were identified as LD-polyethylene. Particle induced X-Ray emission (PIXE) spectroscopy showed that the films contained significant amounts of molybdenum implying the VCI was molybdate-based. Based on the concentration of molybdenum and the age of the film, the samples were divided into three groups. One group had almost constant concentration of molybdenum below 4000 ppm, accordingly 4000 ppm was chosen as lowest concentration offering protection. The other two groups of films had initial concentration of Mo about 6000 ppm and about 8000 ppm that decreased at different rate to reach 4000 ppm in more than 6 years. To confirm the migration of the VCI and the validity of division of samples into the groups, the selected films were kept in vacuum at 50º C for 8 months and then the PIXE measurements were repeated showing significant decrease in Mo concentration corresponding to age of a particular film, the differences between the groups remained. The UV-VIS spectra of the anticorrosion films were recorded showing two prominent absorptions at about 710 and 610 nm. The intensities of absopritons at 710 nm had excellent correlation to molybdenum concentrations determined by PIXE so UV-VIS spectroscopy could be used to control the decrease of VCI concentration.

The small pool of non-bound ferrous iron in cells is known to provide one of the active species involved in probably the most important route for free radical formation leading to increased levels of lipid peroxidation. One of the pathways for excessive production of free radicals is decomposition of hydroperoxides of unsaturated fatty acids catalyzed by iron. Ferrous ions-chelate ligand systems in the presence of LOOH serve as models to establish the reactions that result in the formation of reactive oxyradicals. Rate constants of these reactions are essential to determine which reaction will dominate under selected conditions. However, the literature is scarce and inconsistent with regard to the oxidation of Fe2+ with LOOH in the absence of macromolecular ligands or in the presence of simple unidentate ligands. Further, it is important to consider this mechanism under conditions other than normal physiological ones since, in comparison with normal tissue, tumors have relatively low pH levels. This consideration could also be relevant to a direct involvement of extracellular and intracellular acidosis on the onset of acidosis-associated ischemic disorders. According to the literature, assuming that in the presence of excess Fe2+ the reaction (2) successfully competes to other possible alkoxyl radical reactions in solution (if alkoxyl radicals are stable), the oxidation of Fe2+ with LOOH would proceed in two steps: Fe2+ + LOOH     Fe3+ + LO• + OH– (1) Fe2+ + LO• Fe3+ + LOH (2) The aim of this work was determination of the overall rate constants of oxidation of Fe2+ with various LOOH and with several non-lipidic hydroperoxides in dichloromethane:methanol solvent mixture at 8 × 10– 4 mol dm– 3 HCl. The course of the reactions was followed by spectrophotometric determination of ferric ion complexed with thiocyanate, and these results were compared with the ones obtained in the presence of chloride ions only. The rate constants of the oxidation of Fe2+ ion by LOOHs obtained in non-aqueous medium and their overall energetics with a special attention given to the rate constants and activation energies as affected by the medium composition, have been considered in an effort to attain an insight into the apparent reaction mechanism.Stoichiometry and the rate constant of the oxidation of Fe2+ with ROOH depended on their structure. The average second-order rate constant of the oxidation of Fe2+ with LOOH determined via [FeNCS]2+ complex was 1390 ± 340 dm3 mol– 1 s– 1 ; the rate constants of LOOHs from different biological materials were in the same range. Further, the rates of formation of  FeNCS 2+ complex were mainly twice as high as the rates of formation of  FeCl 2+ complex, 640  140 dm3 mol– 1 s– 1. The activation energies for these reactions average 30 kJ mol– 1. We assume that the oxidation proceeds by an inner-sphere mechanism considering that the breakdown of the successor inner-sphere complex forming reactive alkoxyl radicals probably is the rate-limiting step.

The aim of investigations of hydroperoxide reactivity with iron was to explain the role of free radicals in lipid peroxidation processes. Our study conducted on the oxidation of iron(II) with tert-butyl hydroperoxide (t-BuOOH) in the absence of oxygen suggested that possible involvement of iron in lipid peroxidation in biological systems depends on pre-existing lipid hydroperoxides. It has been shown experimentally that the rate of oxidation of iron(II) with t-BuOOH measured as [FeCl]2+ complex in dichloromethane-methanol solvent mixture was slow at acid medium, about 150 M-1 s-1, increased with decreasing the acid concentration and approaching the physiological conditions the rate constant attained the value of an order of magnitude of 103 M-1 s-1. For all that, very little alteraton of stoichiometry of the oxidation reaction was observed throughout the acidity range. Increasing solvent polarity from the dichloromethane-methanol mixture to water at constant acid concentration of 0.8 mM HCl resulted in hundred-fold decreasing the rate constant of oxidation of iron(II) with t-BuOOH. Further, in the presence of thiocyanate the rate of the oxidation was approximately twice as high as the rate of the oxidation in the presence chloride. Based on these results, a possible mechanism of the effect of solvent, acidity and ligand type on the rate constant is discussed.