Search

The four novel complexes [{cis-PtCl(NH3)2(μ-4,4'-bipyridyl)ZnCl(terpy)}](ClO4)2(C1), [{trans-PtCl(NH3)2(μ-4,4'-bipyridyl)ZnCl(terpy)}](ClO4)2(C2), [{cis-PtCl(NH3)2(μ-pyrazine)ZnCl(terpy)}](ClO4)2(C3) and [{trans-PtCl(NH3)2(μ-pyrazine)ZnCl(terpy)}](ClO4)2(C4) (where terpy = 2,2':6',2''-terpyridine) were synthesized and characterized. Acid-base titrations and concentration dependent kinetic measurements for the reactions with biologically relevant ligands such as guanosine-5'-monophosphate (5'-GMP), inosine-5'-monophosphate (5'-IMP) and glutathione (GSH), were studied at pH 7.4 and 37 °C. The binding of the heterometallic bridged cis- or trans-Pt(II)-Zn(II) complexes to calf thymus DNA (CT-DNA) was studied by UV absorption and fluorescence emission spectroscopy and molecular docking. The results indicated that the complexes bind strongly to DNA, through groove binding, hydrogen bonds, and hydrophobic or electrostatic interaction. The possible in vitro DNA protective effect of cis- and trans-Pt-L-Zn complexes has shown that C3 had significant dose-dependent DNA-protective effect and the same ability to inhibit peroxyl as well as hydroxyl radicals. Antiproliferative effect of the complexes, mRNA expression of apoptosis and repair-related genes after treatment in cancer cells indicated that newly synthesized C2 exhibited highly selective cytotoxicity toward colon carcinoma HCT116 cells. Only treatment with trans analog C2 induced effect similar to the typical DNA damaging agent such as cisplatin, characterized by p53 mediated cell response, cell cycle arrest and certain induction of apoptotic related genes. Both cis- and trans-isomers C1 and C2 showed potency to elicit expression of PARP1 mRNA and in vitro DNA binding.

U poslednjih nekoliko decenija, interes za izučavanjem poznatih i pronalaženjem novih vrsta koje mogu imati značajan antioksidativni potencijal sve više raste. Imajući u vidu da su fenolna jedinjenja poznata kao jako dobri antioksidansi, a da su glavni izvori ovih jedinjenja biljke, konstantno se izučavaju biljne vrste koje potencijalno poseduju visok sadržaj prirodnih antioksidanasa. Familija Rosaceae obuhvata veliki broj biljnih vrsta koje ljudi od davnina koriste u svojoj ishrani, ali su mnoge divlje vrste nedovoljno proučavane, pa je deo ove disertacije baziran na analizi fenolnih jedinjenja u divljim plodovima jabuke, maline i trešnje. U cilju dobijanja maksimalnog prinosa ovih jedinjenja iz biljnog materijala, izvršena je optimizacija metode ekstrakcije fenolnih jedinjenja, i definisani su optimalni uslovi za ekstrakciju, koji obuhvataju pravilan odabir rastvarača (i njegove koncentracije), odnos mase uzorka i zapremine rastvarača, vreme i temperaturu ekstrakcije. U ovako dobijenim ekstraktima, analiziran je ukupan sadržaj fenolnih jedinjenja (ukupnih fenola, fenolnih kiselina, flavonoida i antocijanina), a rezultati su omogućili određivanje optimalnih uslova ekstrakcije ovih jedinjenja u uzorcima primenom softvera Design-Expert® i metodologije odziva površine (eng. Response Surface Methodology). Kvantifikacija pojedinačnih fenolnih jedinjenja u uzorcima dobijenim ekstrakcijom pod optimalnim uslovima izvršena je HPLC metodom, pri čemu su dobijeni rezultati potvrdili da su ovi plodovi bogati sadržajem biološki važnih fenolnih jedinjenja. Dobijene vrednosti koncentracija pojedinačnih fenolnih jedinjenja ukazale su da plodovi ispitivanih samoniklih vrsta familije Rosaceae mogu biti značajan izvor ove grupe jedinjenja u ishrani ljudi. Rezultati i metodologija analize fenolnog sastava ovih plodova, mogu biti od značaja i za buduća ispitivanja i analizu sadržaja fenolnih jedinjenja u plodovima biljaka sličnih karakteristika. Ispitana je i stabilnost i biodostupnost ovih komponenti u organizmu, simulacijom uslova in vitro Ugastrointestinalne digestije. Da bi se rasvetlio antioksidativni potencijal testiranih uzoraka, primenjen je niz metoda koje ispituju njihovu sposobnost da neutrališu štetne slobodno-radikalske vrste. Iako postoji sve veća težnja za nalaženjem i upotrebom prirodnih antioksidanasa, mogućnosti njihove univerzalne primene su često ograničene, pa se pribegava dobijanju antioksidativnih jedinjenja sintetičkim putem. U tom smislu, u ovom radu je izvršena sintetička modifikacija odabranih fenolnih kiselina, sa ciljem nalaženja novih jedinjenja sa boljim biološkim aktivnostima, pre svega antioksidativnom. Na ovaj način su dobijene dve serije jedinjenja, 1,2,4- triazol-3-tioni i 1,3,4-oksadiazoli. Dobijeni rezultati daju doprinos analizi fenolnih jedinjenja u prirodnim proizvodima, njihovoj funkcionalizaciji i primeni In the past several decades, the interest in studying well-known and discovery of new species that may have significant antioxidant potential is constantly growing. Taking into account that phenolic compounds are known as good antioxidants, and that the main sources of these compounds are plants, there is a constant pursuit for plant species potentially possessing a high content of natural antioxidants. The Rosaceae family includes a large number of plant species that humans have used in their diet for a long time, but many wild species are insufficiently studied, therefore part of this PhD thesis is based on the analysis of phenolic compounds in wild apples, raspberries, and cherries (family Rosaceae). In order to obtain the maximum yield of these compounds, optimization of the extraction method of phenolic compounds from plant material was performed, and optimal conditions for extraction, including the appropriate choice of the solvent (and its concentration), the solid to solvent ratio, the time and temperature of the extraction, were defined. The total content of phenolic compounds (total phenols, phenolic acids, flavonoids, and anthocyanins) was analyzed in the obtained extracts, and the obtained results were used in determination of optimal conditions for the extraction of these compounds in the samples using the DesignExpert® software and the response surface methodology. The quantification of individual phenolic compounds in the samples obtained by extraction under optimal conditions was performed by HPLC method and the results confirmed that these fruits are rich in the biologically important phenolic compounds. The obtained concentrations of individual phenolic compounds indicated that the studied wild fruit species of the Rosaceae family could be a significant source of phenolic compounds in human nutrition. The results and methodology of analyzing the phenolic composition of these fruits can be of importance for future research and analysis of phenolic compounds content in fruit or plants with similar characteristics. Furthermore, the stability and bioaccessibility of these components in the organism were examined by the simulation of the in vitro gastrointestinal digestion conditions. In order to clarify the Iantioxidant potential of the tested samples, a number of methods for determination of the ability of obtained extracts to neutralize harmful free-radical species have been applied. Although there is a growing tendency to find and use natural antioxidants, the possibilities of their universal application are often limited, therefore antioxidant compounds are often synthetically obtained. The synthetic modification of selected phenolic acids was carried out with the aim of finding a new series of compounds with better biological activities, mainly antioxidant activity. Two series of novel compounds were synthesized, 1,2,4-triazol-3-thiones and 1,3,4-oxadiazoles. The obtained results in this PhD thesis contribute to the analysis of phenolic compounds in natural products, their functionalization, and application.

Kancer je kompleksna bolest koja je veoma varijabilna u svojoj pojavi, razvoju i ishodu od jednog pacijenta do drugog. To je složeni proces tokom kojeg ćelije podležu dubokim metaboličkim promenama kao što su nekontrolisano razmnožavanje, izbegavanje nadzora od strane imunog sistema i invazija do udaljenih tkiva uz formiranje metastaza. Kancer je jedan od glavnih uzroka morbiditeta i mortaliteta u celom svetu. Antikancerogena jedinjenja ne moraju ispoljavati citotoksični karakter, već je nekada važnije da poseduju antiinvazivni i antimetastatski potencijal. Npr. karcinomi kolona i dojke (zbog fizičke dostupnosti) u današnjim uslovima lako se tretiraju. Međutim, metastatski potencijal ove dve vrste karcinoma je izrazit i svrstava ih u izuzetno agresivne. U tom smislu, kada je reč o tretmanu karcinoma dojke i kolona, sadašnja medicina iskazuje potrebu za novim antimetastatskim lekovima. Organoselenska jedinjenja, OSJ poznata su uglavnom po svom antioksidacionom dejstvu. Sa druge strane postoje i OSJ sa izrazito prooksidacionim osobinama. Na osnovu prethodnog iskustva i literaturnih podataka, u zavisnosti od hemijske strukture moguće je predvideti okvirno dejstvo određenog seleno-jedinjenja. Pretpostavka je da će OSJ koordnovano kao ligand u kompleksu sa paladijumom(II) reagovati citotoksično i prooksidaciono. Redoks ravnoteža je veoma osetljiva, kako u zdravim, tako i u ćelijama kancera. Najmanja promena bilo kog od mnogobrojnih parametara utiče na celu kaskadu proteina i malih molekula u ćeliji pomerajući ovu ravnotežu u jednom od moguća dva smera, prooksidacionom i antioksidacionom. Stoga, promena u hemijskoj strukturi OSJ, kao i u koncentraciji tretmana, može izazvati sasvim drugačiji odgovor na molekularnom nivou ćelije. Hemijska jedinjenja mogu biti donori i/ili akceptori elektrona u zavisnosti od hemijske strukture. Ukoliko određeno hemijsko jedinjenje poseduje potencijal da otpusti elektron, formirajući slobodne radikale, može se očekivati sistemski odgovor ćelije u suprotnom smeru. (De)aktivacija glutationskog sistema na nivou genske i proteinske ekspresije značajno je modulisana uticajem primenjenog hemijskog jedinjenja i značajno utiče na sudbinu ćelije. Cilj doktorske disertacije je da se u in vitro uslovima ispitaju molekularni mehanizmi uticaja nekih OSJ na redoks status imortalizovanih ćelijskih linija kancera kolona HCT-116 i dojke MDA-MB-231. Summary: Cancer is a complex disease that is very variable in its appearance, development and outcome from one patient to another. Cancer is a complex process in which cells are subjected to deep metabolic changes such as uncontrolled reproduction, avoidance of control by the immune system, and invasion of distant tissues by the formation of metastases. Cancer is one of the main causes of morbidity and mortality worldwide. Anticancer compounds do not need to exhibit a cytotoxic character, but it is sometimes more important to have anti-invasive and anti-metastatic potential. For example, colon and breast carcinoma (due to their physical availability) are easily treated in today's conditions. However, the metastatic potential of these two types of cancer is remarkable and places them in extremely aggressive. In that sense, when it comes to treatment of breast and colon cancer, current medicine is showing the need for new anti-metastatic drugs. Organoselenium compounds, OSCs are known mainly for their antioxidant activity. On the other hand, there are also OSCs with highly prooxidative features. Based on previous experience and literature data, depending on the chemical structure, it is possible to predict the indicative effect of a particular selenium compound. The assumption is that the OSC coordinated as a ligand in the complex with palladium(II) will react cytotoxic and prooxidative. Redox balance is very sensitive in both healthy and cancer cells. The smallest change in any of the many parameters affects the whole cascade of proteins and small molecules in the cell by shifting this balance in one of the possible two directions, prooxidative or antioxidative. Therefore, the change in the chemical structure of the OSCs, as well as in the concentration of treatment, may give rise to a completely different response to the molecular level of the cell. Chemical compounds can be donors and/or acceptors of electrons depending on the chemical structure. If a chemical substance has the potential to release the electron, by forming free radicals, the systemic response of the cell may be expected in the opposite direction. (De)activation of the glutathione system at the level of gene and protein expression is significantly modulated by the influence of the applied chemical compound and significantly affects the fate of the cell. The aim of this doctoral thesis is to investigate molecular mechanisms of the action of some OSCs on the redox status of immortalized colon cancer HCT-116 and breast cancer MDA-MB-231 cells, in in vitro conditions.