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Acetylsalicylic acid belongs to nonsteroidal anti-inflammatory drugs with antiinflammatory, analgesic and antipyretic properties. The aim of this work was development and validation of HPLC method for qualitative and quantitative analysis of acetylsalicylic acid and its major degradation product, salicylic acid, in dosage forms. The optimal separation was achived using Zorbax Eclipse XDB-C18 Analytical column (4,6x150 mm, particle size 5 μm) thermostated at 35°C. Mobile phase consisted of eluents A and B in ratio 65:35 (V/V). As the eluent A, water of HPLC purity and 85% phosphoric acid in ratio 80:0.5 (V/V) were used, while acetonitrile was used as the eluent B. The flow rate was 1.0 mL/min and UV detection was performed at 240 nm. The method was validated in terms of selectivity, linearity, precision, accuracy and robustness for both analytes, as well as limits of detection and quantification for salicylic acid. The obtained results meet the requirements of analytical procedures validation. The proposed HPLC method was applied in qualitative and quantitative analysis of acetylsalicylic and salicylic acids in six different forms of drugs. All obtained results meet the requirements of manufacturer specifications. The established HPLC method was found to be rapid, simple, accurate and selective for simultaneous determination of acetylsalicylic and salicylic acids in dosage forms., Acetilsalicilna kiselina pripada grupi nesteroidnih antiinflamatornih lekova koji ispoljavaju antiinflamatorno, analgetičko i antipiretičko delovanje. Cilj ovog rada je bio razvoj i validacija HPLC metode za kvalitativnu i kvantitativnu analizu acetilsalicilne kiseline i njenog degradacionog proizvoda, salicilne kiseline, u doziranim oblicima. Optimalno razdvajanje ispitivanih analita postignuto je na koloni Zorbax Eclipse XDB-C18 Analytical (4,6x150 mm, veličina čestica 5 μm) na temperaturi od 35°C. Mobilnu fazu čine smeša A i B u odnosu 65:35 (V/V). Smeša A je voda HPLC čistoće i 85% fosforna kiselina u odnosu 80:0,5 (V/V), a B je acetonitril. Protok je bio 1,0 mL/min, a talasna dužina detekcije 240 nm. Metoda je validirana i ispitani su sledeći parametri validacije: selektivnost, linearnost, preciznost, tačnost i robusnost za oba analita, kao i limiti detekcije i kvantifikacije za salicilnu kiselinu. Dobijene vrednosti su u skladu sa definisanim kriterijumima za validaciju metode. Predložena HPLC metoda je primenjena za kvalitativnu i kvantitativnu analizu acetilsalicilne i salicilne kiseline u šest različitih komercijalnih preparata. Svi rezultati ispitivanja su u dozvoljenim granicama specifikacija proizvođača. Predložena HPLC metoda pod datim eksperimentalnim uslovima predstavlja brz, jednostavan, tačan i selektivan postupak za istovremeno određivanje acetilsalicilne i salicilne kiseline u doziranim oblicima.

Lipophilicity parameters (logP) were determined for thirteen synthesized β-hydroxy-β-arilalkanoic acids using reversed phase high performance liquid chromatography. Anti-inflammatory activity and potential selectivity towards cyclooxygenase-2 inhibition of synthetized compounds was assessed. Stationary phase was octadecyl modified (C-18) silicagel, and four used mobile phases contained different amount of methanol. Both synthetized and standard compounds with known logP values (aspirin, ibuprofen, ketoprofen, naproxen and phenanthrene) were tested in a chromatographic system. Using retention times for each standard and synthesized compound logk values (logarithm of capacity factor) were calculated. Intercept on a graph showing dependency of logk from methanol amount in the mobile phase for each compound represents logKw(capacity factor when organic solvent amount is zero). Graph showing linear dependency of logP of standard compounds from experimentally obtained logKw values was plotted. LogP values for synthetized compounds were obtained by interpolation from the plotted graph. Obtained values are in a range from 2.901 to 3.847. The best correlation between experimentally obtained and predicted logP values was using KOWWIN software (R2=0.8864), which makes this software appropriate for predicting logP values of this type of compounds., Parametri lipofilnosti (logP) su određeni za trinaest sintetisanih β-hidroksi-β-arilalkanskih kiselina primenom reverzno fazne tečne hromatografije. Ispitivanje je urađeno na derivatima kojima je tokom prethodnih istraživanja okarakterisana antiinflamatorna aktivnost i pretpostavljena je potencijalna selektivnost prema inhibiciji ciklooksigenaze-2. Oktadecil-modifikovani (C-18) silikagel je predstavljao stacionarnu fazu, a korišćene su četiri mobilne faze u kojima je variran udeo metanola. Hromatografski su testirana jedinjenja sa poznatim logP vrednostima (aspirin, ibuprofen, ketoprofen, naproksen i fenantren) i sintetisana jedinjenja. Na osnovu retencionog vremena za svako standardno i sintetisano jedinjenje izračunate su vrednosti logk (logaritam faktora kapaciteta). Odsečak na y osi grafika zavisnosti logk od udela metanola u mobilnoj fazi za svako jedinjenje predstavlja vrednost logKw (vrednost retencionog faktora za hromatografski sistem u kome je sadržaj organske komponente nula) za dato jedinjenje. Konstruisan je grafik zavisnosti logP za standardna jedinjenja od njihovih eksperimentalno dobijenih logKw vrednosti i uspostavljena je linearna zavisnost. Interpolacijom logKw sa grafika su očitane vrednosti logP za sintetisana jedinjenja. Dobijene vrednosti su u opsegu od 2,901 do 3,847. Za predviđanje logP vrednosti korišćeni su računarski programi: AlogPS, Molinspiration, MarvinSketch i KOWWIN. Najbolja korelacija između eksperimentalno određenih i predviđenih rezultata je u programu KOWWIN (R2=0,8864), što čini ovaj program pogodnim za predviđanje logP vrednosti ovog tipa jedinjenja.

Estri (S,S)-1,2-etandiamin-N,N'-di-2-(3-cikloheksil)propanske kiseline(EDCP) sa metanolom (DM-EDCP), etanolom (DE-EDCP), propanolom (DPEDCP),butanolom (DB-EDCP) i izobutanolom (DIB-EDCP) i estri (S,S)-1,3-propandiamin-N,N'-di-2-(3-cikloheksil)propanske kiseline (PDCP) sametanolom (DM-PDCP), etanolom (DE-PDCP), propanolom (DP-PDCP),butanolom (DB-PDCP), izobutanolom (DIB-PDCP), pentanolom (DPE-PDCP) iizopentanolom (DIPE-PDCP) dizajnirani su kao ligandi za Pt(IV) komplekse. Uin vitro ispitivanjima utvrđena je značajna citotoksična aktivnost za navedenekomplekse, ali i za ligande u nevezanom obliku. Ispitivana supstanca DE-EDCPpokazala je najveću citotoksičnu aktivnost.U ovoj doktorskoj disertaciji opisan je razvoj i validacija savremenebioanalitičke metode - ultra visoko efikasne tečne hromatografije u sprezi samasenom detekcijom (UHPLC-MS/MS). Metoda je razvijena i validirana zapotrebe pretkliničkih ispitivanja, odnosno za određivanje ispitivane supstanceDE-EDCP u biološkom materijalu, kao i njenog potencijalnog metabolita EDCP.Kao interni standard primenjen je strukturni analog DB-PDCP.Tokom in vitro fizičko-hemijske biofarmaceutske karakterizacije ispitivanihsupstanci određena je i ocenjena njihova rastvorljivost u vodenom rastvoru,lipofilnost i permeabilnost na veštačkim membranama. Profili rastvorljivostikiselina i njihovih estara se značajno razlikuju, dok su profili rastvorljivosti obekiseline (EDCP i PDCP) slični, kao i profili rastvorljivosti svih estara. Kiseline sedobro rastvaraju u izrazito kiseloj sredini i u izrazito baznoj sredini, dok jerastvorljivost estara najveća u izrazito kiseloj sredini..., Esters of (S,S)-1,2-ethanediamine-N,N'-di-2-(3-cyclohexyl)propanoic acid(EDCP) with methyl alcohol (DM-EDCP), ethyl alcohol (DE-EDCP), n-propylalcohol (DP-EDCP), n-butyl-alcohol (DB-EDCP) and isobutyl-alcohol (DIBEDCP),and esters of (S,S)-1,3-propanediamine-N,N'-di-2-(3-cyclohexyl)propanoic acid (PDCP) with methyl alcohol (DM-PDCP), ethylalcchol (DE-PDCP), n-propyl alcohol (DP-PDCP), n-butyl alcohol (DB-PDCP),and isobutyl alcohol (DIB-PDCP), n-pentyl alcohol (DPE-PDCP) and isopentylalcohol (DIPE-PDCP) were designed as ligand of Pt(IV) complexes. During the invitro investigation it was found significantly cytotoxic activity of thesecomplexes, and also it was found cytotoxic activity of ligand without complexes.Investigated substance DE-EDCP was exerted the strongest cytotoxic activity.In this doctoral dissertation, there is presented a development and validationof a new ultra-high-performance liquid chromatography tandem massspectrometry bioanalytical method (UHPLC-MS/MS). The developed method issupposed for determination of DE-EDCP and its potential metabolit EDCP inbiological materials during non-clinical and clinical studies. The structuralanalogue DB-PDCP was used as an internal standard.During the in vitro biopharmaceutical characterization of the investigatedsubstances, there was performed a determination of solubility, lipophilicity andmembrane permeability. Profiles of solubility of the observed acids and theircorresponding esters are significantly different, while the profiles of solubility fortwo acids (EDCP and PDCP) are similar as well as the profiles of solubility for allthe esters...

Estri (S,S)-1,2-etandiamin-N,N'-di-2-(3-cikloheksil)propanske kiseline (EDCP) sa metanolom (DM-EDCP), etanolom (DE-EDCP), propanolom (DPEDCP), butanolom (DB-EDCP) i izobutanolom (DIB-EDCP) i estri (S,S)-1,3- propandiamin-N,N'-di-2-(3-cikloheksil)propanske kiseline (PDCP) sa metanolom (DM-PDCP), etanolom (DE-PDCP), propanolom (DP-PDCP), butanolom (DB-PDCP), izobutanolom (DIB-PDCP), pentanolom (DPE-PDCP) i izopentanolom (DIPE-PDCP) dizajnirani su kao ligandi za Pt(IV) komplekse. U in vitro ispitivanjima utvrđena je značajna citotoksična aktivnost za navedene komplekse, ali i za ligande u nevezanom obliku. Ispitivana supstanca DE-EDCP pokazala je najveću citotoksičnu aktivnost. U ovoj doktorskoj disertaciji opisan je razvoj i validacija savremene bioanalitičke metode - ultra visoko efikasne tečne hromatografije u sprezi sa masenom detekcijom (UHPLC-MS/MS). Metoda je razvijena i validirana za potrebe pretkliničkih ispitivanja, odnosno za određivanje ispitivane supstance DE-EDCP u biološkom materijalu, kao i njenog potencijalnog metabolita EDCP. Kao interni standard primenjen je strukturni analog DB-PDCP. Tokom in vitro fizičko-hemijske biofarmaceutske karakterizacije ispitivanih supstanci određena je i ocenjena njihova rastvorljivost u vodenom rastvoru, lipofilnost i permeabilnost na veštačkim membranama. Profili rastvorljivosti kiselina i njihovih estara se značajno razlikuju, dok su profili rastvorljivosti obe kiseline (EDCP i PDCP) slični, kao i profili rastvorljivosti svih estara. Kiseline se dobro rastvaraju u izrazito kiseloj sredini i u izrazito baznoj sredini, dok je rastvorljivost estara najveća u izrazito kiseloj sredini..., Esters of (S,S)-1,2-ethanediamine-N,N'-di-2-(3-cyclohexyl)propanoic acid (EDCP) with methyl alcohol (DM-EDCP), ethyl alcohol (DE-EDCP), n-propyl alcohol (DP-EDCP), n-butyl-alcohol (DB-EDCP) and isobutyl-alcohol (DIBEDCP), and esters of (S,S)-1,3-propanediamine-N,N'-di-2-(3- cyclohexyl)propanoic acid (PDCP) with methyl alcohol (DM-PDCP), ethyl alcchol (DE-PDCP), n-propyl alcohol (DP-PDCP), n-butyl alcohol (DB-PDCP), and isobutyl alcohol (DIB-PDCP), n-pentyl alcohol (DPE-PDCP) and isopentyl alcohol (DIPE-PDCP) were designed as ligand of Pt(IV) complexes. During the in vitro investigation it was found significantly cytotoxic activity of these complexes, and also it was found cytotoxic activity of ligand without complexes. Investigated substance DE-EDCP was exerted the strongest cytotoxic activity. In this doctoral dissertation, there is presented a development and validation of a new ultra-high-performance liquid chromatography tandem mass spectrometry bioanalytical method (UHPLC-MS/MS). The developed method is supposed for determination of DE-EDCP and its potential metabolit EDCP in biological materials during non-clinical and clinical studies. The structural analogue DB-PDCP was used as an internal standard. During the in vitro biopharmaceutical characterization of the investigated substances, there was performed a determination of solubility, lipophilicity and membrane permeability. Profiles of solubility of the observed acids and their corresponding esters are significantly different, while the profiles of solubility for two acids (EDCP and PDCP) are similar as well as the profiles of solubility for all the esters...

The pK(a) values of twelve beta-hydroxy-beta-arylalkanoic acids and ibuprofen were determined using a modified RP-HPLC method. The stationary phase was octadecyl modified (C-18) silica gel, and the mobile phases were mixtures of methanol and one of ten different buffers (60: 40 volume ratio). The mean retention time of each compound was plotted against the pH of each of the ten used mobile phases. The inflection point of the obtained sigmoidal curve represents the (s)(w)pK(a) of a compound. Using (s)(w)pKa in previously established equations for the specific methanol/buffer mixture, the (w)(w)pK(a) values (in pure water) were calculated. The obtained wwpKa values for the synthesized compounds were in a range from 3.40 to 3.74, and the (w)(w)pK(a) for ibuprofen was 4.27. The Predicted pK(a) values for this type of compounds in the MarvinSketch 5.11.5. Program were in poor correlation with the experimental results, while in ACD//I-Labs pK(a) values were calculated as a wide range.

Octanol-water partition coefficients (log Po/w) of fifteen previously synthesized 17 beta-carboxamide glucocorticoid derivatives and prednisolone were determined using shake-flask method. The retention behavior of selected compounds was tested in five reversed-phased thin-layer chromatography (RP-TLC) systems, consisting of water and organic solvent (acetonitrile, acetone, ethanol 96%, methanol, or tetrahydrofuran), and chromatography parameters (R-M(0), S, and C-0) were calculated. Simple linear regression (SLR) analysis was performed, and the correlation between log Po/w and chromatography parameters was tested. The most appropriate RP-TLC system for log Po/w prediction was that consisting of water and ethanol 96% as the mobile phase. Statisitical evaluation of the quality of models created using this system proved their reliability for log Po/w prediction of new 17 beta-carboxamide glucocorticoid derivatives, and the model with the most favorable statistical parameters was underlined.

Nesteroidni antiinflamatorni lekovi (NSAIL) se koriste za ublažavanje simptomaakutne i hronične inflamacije već više od pedeset godina. Grupa NSAIL je veomabrojna i obuhvata različite hemijske strukture. Potreba za pronalaženjem novih NSAIL idalje postoji jer neselektivni NSAIL često izazivaju neželjene gastrointestinalne efekte,a neki noviji selektivni lekovi se dovode u vezu sa ozbiljnim neželjenimkardiovaskularnim efektima.U ovoj disertaciji opisani su dizajniranje, sinteza, ispitivanje fizičko-hemijskih ibioloških osobina β-hidroksi-β-arilalkanskih kiselina. U doking studijama je ispitanuticaj α supstitucije jednom ili dvema metil grupama bočnog niza šest prethodno većsintetisanih β-hidroksi-β-arilalkanskih kiselina koje su derivati β-hidroksi-β-bifenilbuterne kiseline ili β-hidroksi-β,β-difenilpropionske kiseline na inhibiciju enzimaciklooksigenaze kao i na selektivnost prema izoformi ciklooksigenaza-2. Dokingstudijama je ispitan uticaj različitih supstituenata (nitro, trifluorometil, metil, metoksi,dimetilamino grupe i hlora) na benzenovom prstenu sedam derivata 3-hidroksi-3,3-difenilpropanske kiseline na inhibiciju i selektivnost prema COX-2 izoformi. Izračunatesu molekulske zapremine za sva dokovana jedinjenja i utvrđeno je da ispunjavaju uslovda su za minimalno 15 Å3 veće od molekulske zapremine ibuprofena, što znači da suove kiseline potencijalno selektivne za COX-2.Modifikovanom Reformatski reakcijom sintetisano je sedam derivata 3-hidroksi-3,3-difenilpropanske kiseline. Tri planirana jedinjenja nije bilo moguće sintetisati naovaj način, kao ni korišćenjem indijuma kao katalizatora, niti klasičnom Reformatskireakcijom. Modifikovana Reformatski reakcija se sastoji iz dve faze. U prvoj fazi sesintetišu α-bromo alkil 1-etoksiestri iz α-bromsirćetne kiseline i etilvinil etra...

Nesteroidni antiinflamatorni lekovi (NSAIL) se koriste za ublažavanje simptoma akutne i hronične inflamacije već više od pedeset godina. Grupa NSAIL je veoma brojna i obuhvata različite hemijske strukture. Potreba za pronalaženjem novih NSAIL i dalje postoji jer neselektivni NSAIL često izazivaju neželjene gastrointestinalne efekte, a neki noviji selektivni lekovi se dovode u vezu sa ozbiljnim neželjenim kardiovaskularnim efektima. U ovoj disertaciji opisani su dizajniranje, sinteza, ispitivanje fizičko-hemijskih i bioloških osobina β-hidroksi-β-arilalkanskih kiselina. U doking studijama je ispitan uticaj α supstitucije jednom ili dvema metil grupama bočnog niza šest prethodno već sintetisanih β-hidroksi-β-arilalkanskih kiselina koje su derivati β-hidroksi-β- bifenilbuterne kiseline ili β-hidroksi-β,β-difenilpropionske kiseline na inhibiciju enzima ciklooksigenaze kao i na selektivnost prema izoformi ciklooksigenaza-2. Doking studijama je ispitan uticaj različitih supstituenata (nitro, trifluorometil, metil, metoksi, dimetilamino grupe i hlora) na benzenovom prstenu sedam derivata 3-hidroksi-3,3- difenilpropanske kiseline na inhibiciju i selektivnost prema COX-2 izoformi. Izračunate su molekulske zapremine za sva dokovana jedinjenja i utvrđeno je da ispunjavaju uslov da su za minimalno 15 Å3 veće od molekulske zapremine ibuprofena, što znači da su ove kiseline potencijalno selektivne za COX-2. Modifikovanom Reformatski reakcijom sintetisano je sedam derivata 3-hidroksi- 3,3-difenilpropanske kiseline. Tri planirana jedinjenja nije bilo moguće sintetisati na ovaj način, kao ni korišćenjem indijuma kao katalizatora, niti klasičnom Reformatski reakcijom. Modifikovana Reformatski reakcija se sastoji iz dve faze. U prvoj fazi se sintetišu α-bromo alkil 1-etoksiestri iz α-bromsirćetne kiseline i etilvinil etra...

Gastrointestinal absorption of thirteen novel beta-hydroxy-beta-arylalkanoic acids (HAA) with anti-inflammatory activity was predicted by use of biopartitioning micellar chromatography and compared to ibuprofen. All tested HAA have lower retention factors (k) and lower expected gastrointestinal absorption than ibuprofen, whereas derivatives with the highest values of k are 1C, 2APTF and 2C. Quantitative structure-retention relationship (QSRR) analysis was performed in order to identify molecular descriptors with the highest influence on k and ANN(k) model was selected as optimal. Descriptors which form this model (nBM, P VSA_LogP_8 and Eta_L) indicate that replacement of phenyl ring with a saturated or partially unsaturated one, as well as presence of halogens and nitro group should positively affect k values. On the basis of these conclusions, six novel HAA were designed and selected QSRR model was used for the prediction of their k values.

Background: Nonsteriodal anti-inflammatory drugs (NSAIDs) are numerous and widely used for more than 60 years, but there is still a strong need for developing novel selective NSAIDs. The need is justified by the fact that nonselective NSAIDs can produce serious gastric side effects and that some of the selective NSAID are withdrawn due to their cardiotoxic side effects. Methods: Eight beta-hydroxy-beta-arylpropanoic acids, which belong to the arylpropanoic acid class of compounds, structurally similar to some nonsteroidal anti-inflammatory drugs (NSAIDs), were docked into 3D catalytic site of both cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2). Seven out of those eight acids were synthesized using already published modification of Reformatsky reaction additionally optimized by increasing temperature. Synthesized compounds were tested in vivo in order to elucidate anti-inflammatory activity, gastric tolerability and impact on liver function of rats. Results: Results of docking studies have indicated that all compounds have potential to selectively inhibit COX-2 isoform, but that the compounds containing polar substituents on phenyl ring are better inhibitors. Results of carrageenan-induced rat paw oedema test have shown that all compounds exhibit dose dependence and good gastric tolerability and none of the tested compounds have shown negative effect on liver function compared to ibuprofen. Conclusion: The compound containing polar nitro group in para position has shown the best docking results, anti-inflammatory activity, low hepatotoxicity and good gastric tolerability.

Prediction of gastrointestinal absorption of thirteen newly synthesized beta-hydroxy-beta-arylalkanoic acids (HAA) and ibuprofen was performed using PAMPA test The highest values of PAMPA parameters (%Tand P-app) were calculated for 1C, 1B and 2C and these parameters were significantly lower in comparison to ibuprofen. QSPR analysis was performed in order to identify molecular descriptors with the highest influence on %Tand-logP(app) and to create models which could be used for the design of novel HAA with improved gastrointestinal absorption. Obtained results indicate that introduction of branched side chain, as well as introduction of substituents on one phenyl ring (which disturb symmetry of the molecule) could have positive impact on gastrointestinal absorption. On the basis of these results, six novel HAA were designed and PAMPA parameters %Tand-logP(app) were predicted by use of selected QSPR models. Designed derivatives should have better gastrointestinal absorption than HAA tested in this study.

The development and validation of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of adapalene in pharmaceutical forms for skin application were presented in this study. The MS/MS analysis of adapalene was performed by use of three mobile phases, consisted of acetonitrile and a) 0.1 % formic acid, b) 0.1 % trifluoroacetic acid and c) 20 mM ammonium acetate. The strongest signals of parent ion and dominant product ion were obtained in negative mode by use of the mobile phase c). The validation of this method was performed according to the ICH guidelines. Small variations of selected chromatographic parameters (concentration of ammonium acetate, mobile phase composition, column temperature and flow rate) did not affect significantly the qualitative and quantitative system responses, which proved the method's robustness. The method is specific for the determination of adapalene. The linearity was proved in the concentration range of 6.7-700.0 ng mL(-1) (r = 0.9990), with limits of detection and quantification of 2.0 and 6.7 ng mL(-1), respectively. The accuracy was confirmed by calculated recoveries (98.4-101.5 %). The precision was tested at three levels: injection repeatability, analysis repeatability and intermediate precision. The calculated relative standard deviations were less than 1, 2 and 3 %, respectively.

Cortienic acid was obtained by periodic acid oxidation of fluocinolone acetonide, whereas corresponding amide was synthesized from the cortienic acid and ethyl ester of b-alanine by dicyclohexylcarbodiimide - hydroxybenzotriazole coupling procedure. Lipophilicity of the amide was evaluated by using reversed-phase thin-layer chromatography systems, consisting of ethanol and water in various ratios, and was higher in comparison to fluocinolone acetonide and cortienic acid.

Predmet ove doktorske disertacije je proučavanje stabilnosti donepezilhidrohlorida, ispitivanjem razgradnih proizvoda nakon različitih uslova forsirane razgradnje. Stabilnost donepezil-hidrohlorida kako u čistom tako i u komercijalnom obliku je ispitivana sprovođenjem studije forsirane razgradnje. Uzorci za ispitivanje su radi toga bili podvrgnuti kiseloj i alkalnoj hidrolizi, oksidaciji i razgradnji pri zagrevanju kao i elektrohemijskoj razgradnji. Ispitivana je i elektrohemijska aktivnost donepezil-hidrohlorida u čistom obliku. Elektrohemijske reakcije su praćene pomoću različitih elektrohemijskih metoda (ciklične voltametrije i voltametrije sa pravougaonim impulsima) na elektrodi od zlata. Za analizu elektrolita u elektrohemijskim eksperimentima korišćene su i druge analitičke metode (HPLC, MS i NMR) radi potvrde podataka dobijenih elektrohemijskim ispitivanjima i objašnjenja procesa elektrohemijske oksidacije i predviđanja stabilnosti donepezil-hidrohlorida. Naučni cilj ovog rada je da se ispitivanjem stabilnosti odgovarajućim transformacijama donepezil-hidrohlorida razviju metode za kvalitativno i kvantitativno određivanje donepezil-hidrohlorida u rastvorima i da se analizom dobijenih rastvora nakon određenih reakcija forsirane razgradnje utvrdi priroda transformacija ispitivanog molekula. U tom cilju izvršena je karakterizacija dobijenih razgradnih proizvoda korišćenjem HPLC tehnika, IR i UV-Vis spektrofotometrije, LC-MS merenjima i 1D i 2D NMR spektroskopskih metoda. Proizvodi dobijeni oksidativnom razgradnjom koji su identifikovani predstavljaju proizvode metabolizma u ljudskom organizmu. Takođe, dobijeni eksperimentalni rezultati su upoređeni sa in-silico predviđenim razgradnim proizvodima uz pomoć softvera za predviđanje hemijskih reakcija. U ovom radu su ispitivani i razgradni proizvodi, koji se literaturno ne pominju u ranijim radovima kao razgradni proizvodi, a proizvodi su transformacije donepezila u oksidaciji u prisustvu oksidacionog sredstva i poseb, The subject of this doctoral thesis is investigation of donepezil hydrochloride stability, by examination of the degradation products formed under different forced degradation conditions. The stability of donepezil hydrochloride both in pure form and in the commercial form is examined by conducting forced degradation studies. Samples were subjected to an acidic and alkaline hydrolysis, oxidation, degradation under thermal conditions as well as the electrochemical degradation. Electrochemical activity of donepezil hydrochloride in a pure form was also investigated. Electrochemical reactions are monitored using various electrochemical methods (cyclic voltammetry and square wave voltammetry) on a gold electrode. For the analysis of electrolytes in electrochemical experiments other analytical methods (HPLC, MS and NMR) were used to confirm the obtained data in electrochemical experiments, to evaluate the involved process of electrochemical oxidation and to predict donepezil hydrochloride stability. The scientific objective of this paper is to investigate the stability and transformations of donepezil hydrochloride involved in order to develop methods for qualitative and quantitative determination of donepezil hydrochloride in solutions and by analyzing the obtained solutions under a certain forced degradation conditions to determine the nature of the transformation of the tested molecule. In this intention the characterization of degradation products was performed using the HPLC technique, IR and UV-Vis spectrophotometry, LC-MS measurements and 1D and 2D NMR spectroscopic methods. Products obtained by the oxidative degradation which have been identified are products of metabolism in the human body. Also, the obtained experimental results were compared with in-silico predicted degradation products with the help of software for predicting chemical reactions. In this study, the degradation products were examined, which are not mentioned in the literature earlier works as d

Twelve angiotensin-converting enzyme (ACE) inhibitors were studied to evaluate correlation between their absorption (ABS) data available in the literature (22-96%) and hydrophobicity parameters (k(m) and P-m/w) obtained in micellar thin-layer chromatography (MTLC) using Brij 35. The theoretical considerations showed that the geometric molecular descriptor-volume value (Vol) should be considered as an independent variable simultaneously with calculated hydrophobicity parameters in multiple linear regression analysis to obtain reliable correlation between ACE inhibitor's absorption and lipophilicity (calculated KOWWINlog P) and that captopril should be excluded from further correlations. The results of MTLC confirmed that between the two hydrophobicity parameters k(m) and P-m/w, for absorption prediction of 11 ACE inhibitors, the micelle-water partition coefficient P-m/w provided higher correlation (R-2 = 0.756), while for the k(m) parameter R-2 = 0.612 was obtained. The micelle-water partition coefficient Pm/w could be considered as analogous to hydrophobicity parameter C-0 from reversed-phase thin-layer chromatography. Dissimilar retention behavior of lisinopril indicated its lowest non-polar interaction with micelle, because of its di-acid form. The proposed model which included ACE inhibitors on the opposite site of lipophilicity-lisinopril and fosinopril (KOWWINlog P = -0.96 and KOWWINlog P = 6.61, respectively), both with similar absorption values (25 and 36%, respectively), could indicate that absorption of investigated compounds occurs via two different mechanisms: active and passive transport.

The L-phenylalanine methyl ester derivative of dexamethasone-derived cortienic acid (DF) was synthesized and its crystal structure characterized by the X-ray diffraction method. The crystal system is orthorhombic with space group P2(1)2(1)2(1) and cell constants a = 8.2969(3) angstrom, b = 18.9358(8) angstrom, c = 20.0904(6) angstrom, V = 3156.4(2) angstrom(3) and Z = 4. Ring A of the steroid nucleus and phenyl ring in the 17 beta-side chain are almost planar. Rings B and C have a slightly distorted chair conformation, whereas ring D has an envelope conformation. The packing of DF is characterized by a network of intermolecular hydrogen bonds involving the O4 atom from one side of the steroid nucleus and O1 and F1 atoms from the other side as hydrogen bond acceptors. Apart from the intermolecular hydrogen bonds in the crystal packing, there are also numerous intramolecular hydrogen bonds of the N-H center dot center dot center dot O, C-H center dot center dot center dot O and C-H center dot center dot center dot F type. The local anti-inflammatory activity of DF was evaluated using the croton oil-induced ear oedema test. This derivative achieved maximal inhibition of ear oedema at significantly lower concentration in comparison with dexamethasone.