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The aim of this PhD thesis was the determination of physicochemical and microbiological parameters in water from artesian wells in the region of Semberija. The study also included analysis of factors which affect the mobility of chemical contaminants. Water samples were taken in the period between February 2011 and January 2012, with monthly sampling frequency. Artesian wells are located in the north Semberija along the Sava River. Electrical conductivity, pH value and temperature were determined in situ. Orthophosphates, ammonium, nitrate and nitrite nitrogen were determined spectrophotometrically, while chlorides and sulphates by ion chromatography. Metals were determined by EAAS, EAAS and ICP-OES techniques. Microbiological parameters were determined using the pour plate technique, the method of membrane filtration and the most probable number method. Obtained results have shown that the water from artesian wells has a weak alkaline character with a high salt content. The concentration of ammonia nitrogen, orthophosphate, arsenic and manganese exceed the exposure limits. Water from artesian wells is microbiologically safe, except at one site (AB9). The presence of intestinal (faecal) streptococci and sulfite-reducing clostridia, whose values exceed the exposure limits, was detected in water from artesian well AB9. Multivariate analysis of metals showed three clearly separated clusters. In the first cluster are artesian wells AB1, AB2, AB3, AB4 and AB5, in the second cluster are AB6, AB7 and AB8, and in the third cluster are AB9 and AB10. Obtained results have also shown that the artesian wells are protected from human influence, and that high levels of ammonia nitrogen, orthophosphate, arsenic and manganese are the result of the geological composition of the soil.

Poslednjih decenija jedan od vodećih problema u medicini je stvaranje rezistentnosti patogenih mikroorganizama na delovanje antibiotika. Bakterije koje pokazuju značajnu rezistentnost na postojeće antibiotike su: meticilin rezistentni Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Acinetobacter spp., itd. Prilikom delovanja na patogene bakterije, antibiotici neselektivno utiču i na nepatogene bakterije, izazivajući pri tom nepredvidive genetske promene. Pored korisnih efekata u delovanju na bakterije, raspoloživi antibiotici, takođe mogu prouzrokovati neželjene efekte kao što su hipersenzitivnost i imunosupresija. To je razlog zbog koga se traga za novim agensima sa antibiotskim delovanjem. Jedan od prirodnih izvora takvih agenasa su etarska ulja i ekstrakti aromatičnih biljaka koji se koriste u tradicionalnoj medicini za lečenje mnogih infektivnih bolesti i bolesti koje nastaju kao posledica oksidativnog stresa. Zbog toga je cilj istraživanja ove disertacije bio da se izvrši komparativna analiza hemijskog sastava, antibakterijske i antioksidativne aktivnosti odabranih biljnih vrstaAngelica pancicii, Angelica sylvestris, Laserpitium latifolium, Achillea grandifolia, Achillea crithmifolia, Artemisia absinthium, Tanacetum parthenium i Hyssopus officinalis koje su veoma zastupljene u tradicionalnoj medicini. Materijal i metode. Biljni materijal koji je korišćen u ovom istraživanju je prikupljan tokom 2012. i 2013. godine na teritoriji jugoistočne Srbije. Nakon sušenja biljnog materijala, pristupilo se procesu izolovanja etarskih ulja metodom hidrodestilacije u aparaturi po Klevindžeru, kao i pripremanju metanolnih ekstrakata alkoholnom ekstrakcijom. Hemijski sastav ulja je analiziran pomoću GH (gasna hromatografija) i GH/MS (gasna hromatografija sa spektrometrijom masa) metoda. Ukupni fenoli su određivani metodom po Folin-Sjoklto-u, sa malim modifikacijama, a ukupni flavonoidi su utvrđivani korišćenjem aluminijum hlorid (AlCl3) kolorimetrijskog metoda. Antioksid, During the last several decades one of the leading challenges in medicine is appearance of resistance of pathogenic microorganisms to antibiotic activity. Bacteria showing significant resistance on existing antibiotics include: methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Acinetobacter spp., etc. During the activity on pathogenic bacteria, the antibiotics simultaneously show non-selective impact on nonpathogenic bacteria, causing unpredictable genetic changes. In addition to beneficial effects on bacteria, the available antibiotics may also cause adverse effects such as hypersensitivity and immunosuppression. Therefore studies of new agents with antibiotic activity are constantly ongoing. One of the natural sources of such agents are essential oils and extracts of aromatic plants used in traditional medicine as a cure for many infectious diseases and ailments caused by oxidative stress. Therefore the goal of study presented in this dissertation was comparative analysis of chemical composition, antibacterial and antioxidant activity of eight chosen plant species regularly represented in traditional medicine: Angelica pancicii, Angelica sylvestris, Laserpitium latifolium, Achillea grandifolia, Achillea crithmifolia, Artemisia absinthium, Tanacetum parthenium and Hyssopus officinalis. The plant material used in this study was collected in 2012 and 2013 in southeastern Serbia. After the plant material was dried, essential oils were isolated by hydro-distillation method using the Clevenger apparatus, while methanol extracts were prepared by alcoholic extraction. The chemical composition of oil was analyzed by GC (gas chromatography) and GC/MS (gas chromatography with mass spectrometry) methods. The total amount of phenols was determined by Folin-Ciocalteu method with slight modifications, while total flavonoids were determined by aluminum chloride (AlCl3) colorimetric method. The antioxidant activity of essential oils and extracts was deter

Composite biomaterials comprising nanostructured hydroxyapatite (HAp) have an enormous potential for natural bone tissue reparation, filling and augmentation. Chitosan (Ch) as a naturally derived polymer has many physicochemical and biological properties that make it an attractive material for use in bone tissue engineering. On the other hand, poly-D,L-lactide-co-glycolide (PLGA) is a synthetic polymer with a long history of use in sustained drug delivery and tissue engineering. However, while chitosan can disrupt the cell membrane integrity and may induce blood thrombosis, PLGA releases acidic byproducts that may cause tissue inflammation and interfere with the healing process. One of the strategies to improve the biocompatibility of Ch and PLGA is to combine them with compounds that exhibit complementary properties. In this study we present the synthesis and characterization, as well as in vitro and in vivo analyses of a nanoparticulate form of HAp coated with two different polymeric systems: (a) Ch and (b) a Ch-PLGA polymer blend. Solvent/non-solvent precipitation and freeze-drying were used for synthesis and processing, respectively, whereas thermogravimetry coupled with mass spectrometry was used for phase identification purposes in the coating process. HAp/Ch composite particles exhibited the highest antimicrobial activity against all four microbial strains tested in this work, but after the reconstruction of the bone defect they also caused inflammatory reactions in the newly formed tissue where the defect had lain. Coating HAp with a polymeric blend composed of Ch and PLGA led to a decrease in the reactivity and antimicrobial activity of the composite particles, but also to an increase in the quality of the newly formed bone tissue in the reconstructed defect area.

Introduction. Coumarins are widely present in the plant’s kingdom and represent a class of bioactive molecules with different functional groups attached to the basic coumarin structure which can be defined as a lactone where benzene ring is connected to α-piron. It was confirmed that molecules with hydroxyl groups attached to the basic coumarin structure exhibit antioxidant activity since they have the ability to react with free radicals. Coumarins are also considered as potential antibacterial agents which inhibit the ATPase activity of bacterial DNA gyrase. Results from a large number of studies have shown that the spectrum of biological activity of coumarins includes anticancer, anti-inflammatory, antibacterial, anticoagulant and immunomodulatory activity. One of the major goals of medicinal chemistry is to find new molecules with the antioxidant activities, which are capable of reacting with free radicals and neutralize their harmful effects. On the other hand, the morbidity and mortality caused by infectious diseases are still a major health issue. The phenomenon of bacterial resistance to existing antibiotics is one of the biggest problems of today's medicine so that rational use of antibiotics in clinical practice and the development of new antibacterial agents with a broad spectrum of activity present contemporary scientific challenges. The isolation of natural compounds and their application as a leading structure for the chemical modification and further pharmacochemical activity improvement, pharmacophore identification and the establishment of quantitative structure activity relationship (QSAR) parallel with in vitro and computer studies are the subject of modern research. Neoflavones present a group of natural compounds with the basic structure of 4- phenylcoumarin. 4-phenyl hydroxycoumarins have a phenyl group at position 4 and hydroxyl groups attached to the basic coumarin structure and coumarins selected for the study in this doctoral dissertation ar

ntroduction. Black currants (Ribes nigrum L.) are berries, introduced in Serbia in the early XX century. There are good agro-climatic conditions for successful cultivation of berries in our country. According to Food and Agriculture Organization (FAO) and Statistical office of the Republic of Serbia production of black currants is on the rise since 2007. Black currants are widely appreciated for their polyphenol composition and vitamin C content. It is known that these compounds prevent and aid the treatment of many diseases such as cardiovascular disease, diabetes and malignancies - chronic non-communicable diseases (CNB). Anthocyanins, the most abundant class of polyphenols, among antioxidant and protective roles, are responsible for the color of black currants and are used in food industry as natural colorants. In the past decade, the use of black currants has spread from the use of their color and flavors in foods and beverages, to their use as functional foods, and additives in the form of antioxidants in meat and preservatives in meat products. The fact that the chemical composition of black currant depends on the plant genotype, led researchers to design and test new varieties of black currants. The aim of this research was to investigate the biological, biochemical and microbiological profile, as well as the possibility of using the juices of four black currant varieties Ribes nigrum L. - Triton, Tenah, Ben Sarek and Ometa as functional food and their extracts, as dietary supplements. Antioxidant and antimicrobial activity were determined, as well as total and dominant anthocyanins, total polyphenols and tannins, flavonoids and vitamin C. The study included the effects of juices and extracts on the smooth muscles of rat small intestine, as well as the ability to reduce blood pressure and contraction of the rabbit atria. The research also included the impact of agroecological factors on the chemical composition of each variety and statistically significant di