Provider: - Institution: - Data provided by Europeana Collections- U ovom doktorskom radu sintetizirani su Cu(II) molekulski kompleksi Cu(1-TsC-N3)2Cl2 i Cu(1-MsC-N3)2Cl2 biološki aktivnih ...N-sulfonilcitozinskih (C) liganada s tosilom (Ts) i mezilom (Ms) te novi ciklam-TsC konjugati. Mannichova reakcija TsC liganda, paraformaldehida i ciklama u prisutnosti octene kiseline daje C-aminometilirani konjugat u kojem je ciklam vezan preko metilenskog mosta na C5 položaj citozina. Ista reakcija sa zaštićenim ciklamom daje C4 aminometilirani produkt. Pomoću ESI-MS metode provedena je studija stabilnosti i utjecaja biološki važnih metalnih iona (Na+, K+, Ca2+, Mg2+, Zn2+, Cu2+) na ligande, Cu(II) komplekse, te na poliaza makrocikličke konjugate. U interakciji s ligandima i Cu(II) kompleksima alkalijski metali uslijed elektrostatskih interakcija stvaraju klastere, dok je nastanak bis i tris te miješanih kompleksa uočen u interakciji s Ca2+ i Mg2+. Interakcija Zn2+ s ligandima i Cu(II) kompleksima rezultira nastankom monometalnih kompleksa kao i dimetalnih kompleksa zbog afniteta Zn2+ prema atomima kisika i dušika koji u strukturu uključuju molekule vode. Novi poliaza makrociklički konjugati u interakciji s CuCl2 stvaraju molekulske komplekse u kojima je CuCl2 u ciklamskom prstenu, a u interakciji s ZnSO4 nastaju ionski kompleksi u kojima je Zn2+ smješten u ciklamskom prstenu.- Abstract In this doctoral thesis, Cu (II) molecular complexes Cu(1-TsC-N3)2Cl2 and Cu(1-MsC-N3)2Cl2 of biologically active N-sulfonylcytosine ligands (C) with tosyl (Ts) and mesyl (Ms) and new cyclame-TsC conjugates were synthesized. The Mannich reaction of TsC, paraformaldehyde and cyclame in the presence of acetic acid yields C-aminomethylated konjugate in which the cyclame was introduced through a methylene bridge at C5 position of cytosine. The same reaction with protected cyclame gives C4 aminomethylated product. Using ESI-MS method was conducted stability studies and the influence of biologically important metal ions (Na+, K+, Ca2+, Mg2+, Zn2+, Cu2+) to ligands, Cu (II) complexes, and polyaza macrocyclic conjugates. The interaction of ligands and Cu (II) complexes with biologically important metal ions results with formation of various metal complex. Alkali metals Na+ and K+ formed clusters due to the electrostatic inetractions. Bis, tris and mixed ligand complexes were observed upon mixing with Ca2+ or Mg2+ salt. Interaction with Zn2+ sieed monometal Zn2+ complexes and mixed ligand dimetal complexes that includ water molecules in the structures of the complexes because of affinity of Zn2+ for both O and N atoms. Both ions Cu2+ and Zn2+ were located within the cyclamic ring upon their interaction with polyaza macrocyclic conjugates. Newly formed Cu2+complexes were molecular while the ionic complexes were formed with zinc ions.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Peptidi i proteini imaju ključnu ulogu u nizu bioloških i fizioloških procesa; međutim, njihova primjena kao terapeutika je ...ograničena slabom stabilnošću i biodostupnošću. Stoga je razvoj peptidomimetika, spojeva koji oponašaju strukturu i/ili funkciju proteina od velikog značaja za akademsku zajednicu i farmaceutsku industriju. Cilj istraživanja predloženih u okviru doktorske disertacije je priprava peptidomimetika korištenjem hidrazino-derivata -aminokiselina. Istraživanja će uključivati: razvoj metodologije za pripravu optički čistih hidrazino-derivata -aminokiselina te razvoj metodologije za pripravu hidrazino-peptidomimetika postupnom sintezom u otopini i primjenom u višekomponentnim reakcijama. Istraživanja bi trebala rezultirati optimiranim uvjetima priprave hidrazino-derivata -aminokiselina i hidrazino-peptidomimetika te potpuno novom skupinom peptidomimetika s ugrađenom hidrazino-jedinicom.- Peptides and proteins have a crucial role in a number of biological and physiological processes; however, their use as therapeutics is limited by poor stability and bioavailability. Therefore, the development of peptidomimetics, compounds that mimic structure and/or function of proteins is of great importance for the academic community and the pharmaceutical industry. The objective of the research proposed in this doctoral thesis is the preparation of peptidomimetics using hydrazino derivatives of -amino acids. Therefore, studies include: development of methodologies for the preparation of optically pure hydrazino derivatives of -amino acids; development of methodology for the preparation of hydrazino peptidomimetics by stepwise synthesis in solution and by multicomponent reactions. Expected results are: optimized conditions for the preparation of hydrazino derivatives of -amino acids and hydrazino peptidomimetics and a new class of peptidomimetics comprising hydrazino moiety. Item Type: Thesis (Doctoral thesis)- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Biginellijevom reakcijom, pripravljeni su razliĉito supstituirani derivati 3,4-dihidropirimidinona. Koristeći modelni derivat ...124-I-b provedena su opsežna preliminarna ispitivanja u svrhu pronalaska odgovarajućih uvjeta aromatizacije sintetiziranih derivata. Opseg preliminarnih ispitivanja potkrepljuje literaturno poznatu ĉinjenicu kako se ovaj tip spojeva vrlo teško aromatizira. Rezultat istraţivanja u sklopu ove doktorske disertacije urodio je ĉetirima novim, do sad nepoznatim metodama aromatizacije 3,4-dihidropirimidinona. Efikasna, brza i selektivna metoda aromatizacije razvijena je uz molekularni jod i kalijev t-butoksid u suhom tetrahidrofuranu pri sobnoj temperaturi (konverzija 80 % - 100 %). Ispitan je i predloţen mehanizam aromatizacije koji upućuje na nastanak t-butilhipojodita kao aktivne vrste pri reakciji aromatizacije. Aromatizacija 3,4-dihidropirimidinona uz t-butilhidro-peroksid, molekularni jod i kalijev t-butoksid u t-butilacetatu, pri temperaturi povrata otapala, modificirana je, katalitiĉka verzija prethodno opisane metode ĉiji je mehanizam dehidrogenacije također predloţen. Zabilježena je konverzija reaktanata u produkte od vrlo visokih 98 % - 100 %. Niz supstituiranih derivata oksidiran je i efikasnom metodom uz t-butilhidroperoksid i kalijev hidroksid uz kalijev jodid kao katalizator. Reakcije su provedene u metanolu pri sobnoj temperaturi (konverzija 98 % - 100 %). Derivati 4-aril-pirimidin-2(1H)-ona dehidrogenirani su u odgovarajuće 4-aril-pirimidin-one metodom uz tetracijanoetilen u acetonitrilu pri povišenoj temperaturi. Aromatizacijom razliĉito supstituiranih derivata ovom metodom postignuta je maksimalna konverzija reaktanata u produkte (100 %). U završnoj fazi istraživanja provedena je i vezana sinteza prva tri koraka pri sintezi rosuvastatin kalcija na 17 razliĉito supstituiranih derivata 3,4-dihidropirimidinona. Ova sinteza ukljuĉuje aromatizaciju 3,4-dihidropirimidinona, aktivaciju dobivenog pirimidinona na položaju 2 azaheterocikliĉke jezgre te reakciju supstitucije tako pripremljenog produkta s odgovarajućim nukleofilom. Sva tri stupnja nadogradnje provedena su u jednoj reakcijskoj tikvici, bez izolacije međuprodukata, uz iskorištenje od 12 % - 71 %.- Differently substituted 3,4-dihydropyrimidinones were prepared using a three component Biginelli reaction. By using a model compound 124-I-b, extensive preliminary research was done in order to find a new appropriate 3,4-dihydropyrimidinone aromatization method. A wide range of reaction conditions, reagents, catalysts and solvents were examined. The scope of the preliminary examination supports the literature known fact that this kinds of compounds are very difficult to be aromatized. The research in the context of this PhD thesis has resulted in four new, so far unknown methods of 3,4-dihydropyrimidinone aromatization. Efficient, rapid and selective aromatization method was developed using molecular iodine and potassium t-butoxide in dry tetrahydrofuran at room temperature (conversion 80 % - 100 %). 3,4-Dihydropyrimidinone aromatization mechanism was proposed. It includes the formation of t-butil hypoiodite as an active species during aromatization. The second aromatization method is catalytic modification of the previously described method - aromatization of 3,4-dihydropyrimidinones using t-butyl hydroperoxide, molecular iodine and potassium t-butoxide in t-butyl acetate at reflux temperature (conversion 98 % - 100 %). The series of differently substituted derivatives were oxidized using on efficient method that includes t-butyl hydroperoxide as an oxidant, potassium hydroxide as a base and potassium iodide as a catalyst. Reactions were carried out in methanol at room temperature (conversion 98 % - 100 %). In the last aromatization method, the 4-aryl-pyrimidin-2(1H)-one derivatives were dehydrogenated to the corresponding 4-aryl-pyrimidine-ones using tetracyanoethylene in acetonitrile at elevated temperatures (conversion 100 %). The final stage was one pot synthesis of the first three steps in the synthesis of rosuvastatin calcium. This synthesis includes 3,4-dihydropyrimidinone aromatization, the activation of dehydrogenated product and a substitution reaction with an appropriate nucleophile. All three stages were carried out in a single reaction flask without isolation of intermediates. The corresponding products were obtained in a yield of 12 % - 71 %, depending on the derivative.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Rod Centaurea, porodica Asteracea, taksonomski je vrlo složen, a 80 od ukupno 400 do 700 vrsta nalazimo na području Republike ...Hrvatske. Cilj ovoga doktorskog rada bio je odrediti fitokemijski i citogenetski profil odabranih vrsta roda Centaurea: Centaurea ragusina, Centaurea rupestris i Centaurea solstitialis. Fitokemijski profil, određen kroz kemijski sastav izoliranih hlapljivih ulja, istražen je vezanim sustavom plinska kromatografija - masena spektrometrija. Citogenetski profil, određen kao veličina genoma i osnovni broj kromosoma istraživanih vrsta, istraživan je protočnom citometrijom i standardnim kariološkim metodama. Citogenetski profil fitokemijski proučavanih vrsta u skladu je s prethodnim istraživanjima, čime je utvrđena autentičnost istraživanih vrsta bez dvojbe prilikom botaničke determinacije. Dominantne su komponente hlapljivih ulja odabranih vrsta roda Centaurea neoksidirani i oksidirani seskviterpenski spojevi te neterpenske kiseline i ugljikovodici. Germakren D, -kariofilen i heksadekanska kiselina identificirani su u svim proučavanim eteričnim uljima. Izolirana hlapljiva ulja pokazuju slab antioksidacijski potencijal i slabu sposobnost inhibicije acetilkolinesteraze i butirilkolinesteraze kao i značajan antimikrobni potencijal.- The Centaurea genus, Asteraceae family, taxonomically is very complex. It contains 80 species from Croatia, of about 400 up to 700 in total. The aim of this doctoral thesis was to determine the phytochemical and cytogenetic profiles of selected Centaurea species: Centaurea ragusina, Centaurea rupestris and Centaurea solstitialis. Phytochemical profile, determined as chemical composition of isolated volatile oil, was assesed with associated gas chromatography-mass spectrometry. Cytogenetic profile, expressed as genome size and chromosome number, was assessed by flow cytometry and standard karyological methods. Cytogenetic profile of species selected for phytochemical research, is in accordance with previous research, which aproves authenticity of the studied taxa. Dominant components of volatile oils of Centaurea species are oxidized and nonoxidized sesquiterpenes, and nonterpene acids and hydrocarbons. Germacrene D, -caryophyllene and hexadecanoic acid are identified in all Centaurea volatile oils. Isolated volatile oil showed weak antioxidant potential and inhibiton of acetylcholinesterase and butyrylcholinesterase, as well as significant antimicrobial potential.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Poznato je da prirodni spoj trans-resveratrol (trans-3,5,4'-trihidroksistilben, ArOH) posjeduje izrazitu biološku aktivnost. Unatoč ...poznavanju mogućih mehanizama antioksidacijskog djelovanja kojima se pridjeljuje protektivna uloga ArOH u živim organizmima, o njegovim kemijskim svojstvima se malo zna. Cilj ove disertacije je istražiti kinetike i mehanizme reakcija ArOH s do sada neistraženim radikalima koji nastaju u uvjetima stanja oksidacijskog stresa. Ovi radikali i pobuđena stanja ArOH generirani su svjetlosnim pulsom koristeći rubinski i Nd:YAG laserski uređaj odnosno pulsom ubrzanih elektrona. Tranzijentnom apsorpcijskom spektroskopijom detektirane su intermedijerne vrste te određene konstante brzina reakcija ArOH s radikalima lokaliziranim na kisiku, ugljiku i sumporu odnosno s aril-ketonima u tripletnim stanjima. Reakcije su praćene na vremenskim skalama reda veličine 1061012 s u acetonitrilu i otopinama alkohol/voda. Budući da je poznato da su istraživani radikali odgovorni za poremećaje u odvijanju normalnih procesa u stanicama živih organizama, rezultati ovih istraživanja su originalan doprinos razumijevanju mehanizama i kinetike reakcija ArOH s biološki značajnim radikalima.- It is well known that natural compound trans-resveratrol (trans-3,5,4'-trihydroxystilbene) possesses significant biological activity. However, despite the knowledge of its possible antioxidant mechanisms which have a protective role in the living organisms, chemical properties of ArOH are less known. The main goal of this thesis is to investigate reaction kinetics and mechanisms of ArOH with so far unresearched free bioradicals which occur in the conditions of oxidative stress. These free radicals and ArOH excited states were generated with ruby or Nd:YAG laser flash or electron accelerator pulse. Short-lived intermediate species of ArOH and its reaction kinetics with oxygen, sulphur and carbon-centered radicals and aromatic carbonyl triplets were determined with transient absorption spectroscopy. Measurements were conducted at the 1061012 sec time scales in acetonitrile and solutions of water/alcohol. This research is original contribution to the understanding of the mechanism and reaction kinetics of ArOH antioxidant activity with biologically relevant free radicals under investigation which are known to be responsible for the malfunction of the normal processes in living cells.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- U radu je istražena mogućnost primjene titanatnih nanocjevčica kao čvrstog nosača za imobilizaciju katalizatora u elektrokemijskim ...(amperometrijskim) senzorima. Titanatne nanocjevčice površinski su modificirane (3-aminopropil)trimetoksisilanom (APTMS), pri čemu je istražen utjecaj reakcijskih uvjeta na strukturu siloksanskog sloja nastalog na površini titanatnih nanocjevčica. Površinske amino-skupine titanatnih nanocjevčica modificiranih s APTMS iskorištene se kao reaktivna mjesta za kovalentnu imobilizaciju redoks-enzima peroksidaze, odn. kovalentno vezanje katalitički aktivnog N-saliciliden-n-propilaminskog kompleksa željeza(III) na površinu titanatnih nanocjevčica. Titanatnim nanocjevčicama modificiranim peroksidazom, odn. N-saliciliden-n-propilaminskim kompleksom željeza(III) istražena su elektrokemijska i elektrokatalitička svojstva. Ustanovljeno je da peroksidaza nakon imobilizacije na površinu titanatnih nanocjevčica zadržava katalitičku aktivnost te da molekule imobilizirane peroksidaze mogu sudjelovati u izravnom prijenosu elektrona između redoks-centra enzima i elektrode, odn. vodljive matrice u koju su nanocjevčice ugrađene. Titanatne nanocjevčice s imobiliziranom peroksidazom s uspjehom su uporabljene za izradu amperometrijskog biosenzora za detekciju vodikova peroksida i dvoenzimskog biosenzora za određivanje glukoze.- In this thesis, the possibility of application of titanate nanotubes as a solid substrate for immobilization of catalysts in electrochemical (amperometric) sensors was studied. Titanate nanotubes were surface modified with (3-aminopropyl)trimethoxysilane (APTMS) and the influence of reaction conditions on the structure of siloxane layer formed on the surface of titanate nanotubes was studied. Surface amino-groups of titanate nanotubes modified with APTMS were exploited as a reactive sites for covalent immobilization of the redox enzyme peroxidase and for covalent bonding of N-salicyliden-n-propylamino complex of iron(III) on the surface of titanate nanotubes. Titanatne nanototubes modified with peroxidase or with N-salicyliden-n-propylamino complex of iron(III) were embedded into the conductive graphite composite and its electrocatalytic properties were examined. It was found that after immobilization on the surface of titanate nanotubes, peroxidase retains its catalytic activity and that the molecules of immobilized peroxidase can effectively participate in direct electron transfer between the enzyme redox center and electrode or the conductive matrix in which the nanotubes were embedded. Titanate nanotubes with immobilized peroxidase were successfully employed in the construction of amperometric hydrogen peroxide biosensors of the third generation and in the construction of the bi-enzyme biosensor for glucose detection.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Enzim lipoksigenaza (LOX) je dio lipoksigenaznog puta koji ima značajan utjecaj na sastav hlapljivih komponenti, kako u plodu ...masline tako i u ulju. U ovom radu ispitan je utjecaj stupnja zrelosti ploda na aktivnost LOX enzima u plodovima autohtonih dalmatinskih sorti maslina Oblica, Levantinka i Lastovka. Kako bi se aktivnost LOX enzima dovela u vezu sa sintezom poželjnih hlapljivih spojeva, istraživanje je obuhvatilo i sadržaj hlapljivih tvari u sortnim djevičanskim uljima. Također je analiziran sadržaj ukupnih fenolnih spojeva koji pridonose aromi djevičanskog ulja, a utječu na učinkovitost lipoksigenaze. Rezultati dobiveni ovim istraživanjem, omogućuju uvid u sortne karakteristike maslina i pripadajućeg maslinovog ulja, što ima poseban značaj u proizvodnji ulja poželjnih mirisnih svojstava i pridonosi definiranju bioraznolikosti autohtonih sorti.- Lipoxygenase (LOX) is a part of the lipoxygenase pathway, which has a substantial role regarding the composition of volatile compounds in olive fruit and olive oil. In this thesis LOX activity of Dalmatian autochthonous olive cultivars, namely Oblica, Levantinka and Lastovka, has been explored in response to the degree of olive fruit ripeness. The research included the analysis of volatile compounds in respective olive oils, with correlation to LOX activity. The total amount of phenolic compounds contributing to olive oil flavor has also been determined. The results of this study will give an insight into cultivar-dependent features of Dalmatian olive trees and associated olive oils. This is of importance regarding the production of olive oils displaying desirable flavor characteristics, and in defining olive tree autochthonous cultivar biodiversity.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- U cilju istraživanja utjecaja strukture na fizikalno-kemijska svojstva krutih spojeva s biološki aktivnim kolatnim anionom (Ch), ...sintetizirana su tri tipa kompleksa (katanionski, metaloamfifilni i gostdomaćin) skloni stvaranju supramolekulskih membrana. Korišten je niz eksperimentalnih tehnika: CHN analiza, NMR, IR spektroskopija, DSC, difrakcija rentgenskih zraka (WAXD i SAXD), mikroskopija (SM i SEM), te DFT računi. Katanionski amfifili sintetizirani su interakcijom natrijevog kolata (NaCh) i kvaternih amonijevih soli, varirajući broj n-dodecilnih lanaca na ionskoj grupi (nc), odn. broj ionskih grupa (nh) u molekuli. Struktura katanionika na sobnoj temperaturi (RT) je atipična dvoslojna, a na povišenim temperaturama smektička (Sm); ispitivana je zavisnost polimorfnih i mezomorfnih svojstava, termodinamičkih parametara i debljine dvosloja o nc i nh. Metaloamfifili su pripravljeni interakcijom NaCh s Ag(I), Ca(II), Ba(II) i La(III) solima, te neutralizacijom Ag(I) oksida ili Ca(II) hidroksida kolnom kiselinom. Interakcija Ch i metalnih kationa u područjima viših koncentracija rezultira geliranjem, s bidentantnom koordinacijom Ch. Adicijom NaCh; natrijevog 4-(1-pentilheptil)benzensulfonata (NaDBS); n-dodecilsulfata (NaDS); odn. kalijevog pikrata (KP) u šupljinu 18C6 etera dobiveni su gostdomaćin kompleksi. Pri sobnoj temperaturi strukture su dvoslojne, dok s povišenjem temperature formiraju mezofaze, pretežno Sm (18C6.NaDS i 18C6.NaDBS) ili kolesteričke (18C6.NaCh).- In order to explain the effect of structural factors on the physico-chemical properties of solid compounds based on biologically active cholate ion (Ch), three types of complexes (catanionic, metaloamphiphilic and hostguest) that show tendency to form supramolecular membranes were synthesized. Various experimental techniques were used: CHN analysis, NMR, IR spectroscopy, DSC, X-ray diffraction (WAXD and SAXD), microscopy (POM i SEM), and DFT calculations. Catanionic amphiphiles were sythesized by the interaction of sodium cholate (NaCh) and quaternary ammonium salts, by varying the number of n-dodecyl chains on the ionic group (nc), and the number of ionic groups (nh) in the molecule. The room temperature (RT) structure of catanionics is atipical bilayer, and smectic (Sm) at higher temperatures. The dependence of polymorphic and mesomorphic properties, thermodynamic parameters and bilayer thickness on nc and nh was studied. Metaloamphiphiles were sythesized by the interaction of NaCh with Ag(I), Ca(II), Ba(II) or La(III) salts, and by neutralization of Ag(I) oxide or Ca(II) hydro(oxyde) with cholic acid. Interaction of Ch and metal cation at higher concentration range results in gelation, and bidentante coordination of Ch. Addition of NaCh; sodium 4-(1-pentylheptyl)benzenesulfonate (NaDBS); n-dodecylsulfate (NaDS); potassium picrate (KP) into the 18C6 ether cavity forms hostguest complexes. The RT phases of addition complexes are bilayered, while mesophases are formed at higher temperatures, mostly Sm (18C6.NaDS i 18C6.NaDBS) or cholesteric (18C6.NaCh).- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Razvijena je multirezidualna metoda za određivanje 25 pesticida u vinima plinskom kromatografijom vezanom sa spektrometrijom masa. ...Optimirana je ekstrakcija na čvrstoj fazi uz sorbens OASIS HLB te postupak ekstrakcije QuEChERS s težištem na optimizaciji koncentracije dodanih soli radi podešavanja raspodjele analita između dviju faza. Za svaki postupak priprave uzorka provedena je validacija za crno i bijelo vino kao dvije zasebne matrice uzorka. Granice određivanja pesticida za oba postupka bile su u rasponu od 0,01 g L1 do 250 g L-1. Preciznost, izražena kao relativna standardna devijacija, bila je <20 %, dok je točnost, izražena kao analitički povrat, za većinu pesticida bila u rasponu od 70 % do 120 %. Ispitan je utjecaj matrice na određivanje pesticida pri čemu je izračunata djelotvornost postupaka priprave uzorka. U okviru validacije metoda procijenjena je mjerna nesigurnost koja je bila <50 % za većinu pesticida. Predloženim analitičkim postupcima analizirana su 63 uzorka različitih vina da bi se dobio prvi uvid u koncentracije ostataka pesticida u vinima s područja Hrvatske.- A new multiresidue method was developed for determination of 25 pesticides in wines by gas chromatography mass spectrometry. Two sample preparation procedures were optimized; solid phase extraction using OASIS HLB and QuEChERS procedure, where salt concentrations were optimised in order to adjust the distribution of pesticides between two immiscible phases. Method validation, including uncertainty estimation (<50 % for most pesticides), was performed independently for red and white wine as two different matrices and for each sample preparation procedure. Limits of quantification were between 0,01 g L-1 and 250 g L-1. The recoveries of most pesticides were between 70 % and 120 % with relative standard deviations <20 %. The matrix effect was investigated and the quality of sample preparation procedures has been evaluated in terms of extraction efficiency. The proposed analytical procedures were applied to 63 Croatian wine samples of different varieties in order to provide the first insight into pesticide residue concentrations in Croatian wines.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Sažetak Organofosforni spojevi (OP), kao što su živčani bojni otrovi (tabun, soman, VX),ireverzibilno inhibiraju acetilkolinesterazu ...(AChE) i butirilkolinesterazu (BChE). Terapija u slučaju izloženosti OP spoju je nužna i uključuje primjenu antikolinergika atropina i oksima, reaktivatora AChE. Ta terapija je nedostatna pa se danas, između ostalog, istražujupseudokatalitička čistila enzimi dizajnirani s ciljem da se njihovom cikličkom inhibicijom i reaktivacijom razgradi OP spoj prije nego što on inhibira esencijalnu sinaptičku AChE. Ispitana je učinkovitost 17 oksima u reaktivaciji ljudske AChE, BChE, Y337A i Y337A/F338A inačica AChE, inhibiranih tabunom, VX-om i somanom. Prema određenimkinetičkim parametrima izdvojeni su najučinkovitiji oksim-enzim parovi za razgradnju spomenutih OP spojeva u ex vivo uvjetima. Pokazano je da neki od ispitanih oksimima u kombinaciji s navedenim enzimima čine učinkovit sustav pseudokatalitičkog čistila za razgradnju tabuna (1-heksil-2-(hidroksiiminometil)piridinijev klorid (JAR288C) i Y337A), VX-a (HI-6 i Y337A/F338A) te somana (HI-6 i Y337A/F338A). Značajne odlike ovih parova oksima i inačica AChE su maksimalna konstanta brzine reaktivacije viša od 0,2 min-1, disocijacijska konstanta oksim-enzim kompleksa oko 0,1 mmol dm-3, visoki postotak reaktivacije te konstanta brzine inhibicije barem reda veličine one za nativnu AChE. Ovi kinetički parametri predstavljaju nužne kriterije za razgradnju OP spojeva potpomognutu oksimom i enzimom, odnosno za učinkovita pseudokatalitička čistila živčanih bojnih otrova.- Organophosphates (OP) such as nerve agents (tabun, soman, VX) irreversibly inhibit acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The treatment in case of exposure to OP compounds includes the administration of the anticholinergic drug atropine and an oxime reactivator. Since this therapy has proven insufficient, today, among other solutions, pseudo-catalytic bioscavengers, enzymes designed with the aim to degrade OPs with turnover before it interacts with synaptic AChE, are investigated as prophylactics. We tested 17 oximes as reactivators of human AChE, BChE, Y337A and the Y337A/F338A mutant of AChE inhibited by tabun, VX and soman. The most effective oxime-enzyme couples identified were further tested ex vivo for degradation of tabun, VX or soman by oxime-enzyme assisted hydrolysis. It was shown that among the studied oximes there were those that in combination with the investigated enzymes could serve as pseudo-catalytic bioscavengers of tabun (oxime 1-hexyl-2-(hydroxyimino)methylpyridinium chloride (JAR288C) and Y337A mutant), VX (oxime HI-6 and Y337A/F338A mutant) and soman(oxime HI-6 and Y337A/F338A mutant). The tested oximes and AChE mutant pairs reactivated a high percentage of enzyme activity, achieving reactivation rate constants above0.2 min-1, oxime-mutant dissociation constants about 0.1 mol min-1 dm-3 and a rate of enzyme inhibition within the range of native AChE inhibition. These catalytic parameters represent the necessary criteria for oxime-enzyme induced OP degradation, i.e. for effective nerve agent pseudo-catalytic bioscavengers.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
