Please read the abstract (Summary) in the section, 00front of this document / Thesis (DPhil)--University of Pretoria, 2008. / Pharmacology / DPhil / Unrestricted

This investigation deals with the study of the possible antibiotic effect of oleoresins of one hundred common Texas plants upon twenty-five gram-negative bacterial organisms.

The purpose of this problem is to determine the presence and extent of antibiotic materials as found in the oleoresins of a selected group of garden vegetables. The problem has consisted of, first, the collection and preparation of specimens of twenty-five commonly used garden vegetables; second, the extraction of the oleoresins from these; third, the determination of the inhibitory and other effects of these oleoresins against several strains of selected gram-positive and gram-negative bacteria; and fourth, the evaluation of the potentialities of these oleoresins with regard to their future use as medicinal prophylactics and therapeutics.

Orientadores: Pedro Luiz Rosalen, Cínthia Pereira Machado Tabchoury / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-26T11:28:01Z (GMT). No. of bitstreams: 1 Paula-Eduardo_LailaFacinde_M.pdf: 1396217 bytes, checksum: ee32ae3fccb5fc73fe047b8152a78b6e (MD5) Previous issue date: 2014 / Resumo: Os produtos naturais, comprovadamente, têm sido uma fonte promissora para descoberta de novos compostos bioativos. Dentre eles, a própolis coletada por abelhas Apis mellifera possui atividades biológicas descritas na literatura como anticárie, antibacteriana, anti-inflamatória, entre outras. Entretanto, a maioria dos estudos sobre própolis se refere àquelas coletadas por A. mellifera e pouco se tem conhecimento de outras, como a geoprópolis, produzida por abelhas sem ferrão do gênero Melipona. Em estudos recentes, a geoprópolis apresentou promissoras atividades antimicrobiana e anti-inflamatória, porém estas pesquisas ainda não evidenciaram quais as substâncias responsáveis por tais ações biológicas, especialmente contra o biofilme oral cariogênico. Portanto, o objetivo desse trabalho foi isolar e identificar o composto ativo da geoprópolis de Melipona scutellaris com atividade contra biofilme formado por Streptococcus mutans. Este objetivo foi alcançado por meio das seguintes metodologias: 1- fracionamento bioguiado do extrato etanólico da geoprópolis (EEGP); 2- isolamento e identificação do composto ativo; 3- avaliação do potencial anticárie do composto ativo utilizando modelo in vitro de inibição de biofilme oral monoespécie. Como resultado do fracionamento bioguiado foi isolado e identificado o composto nemorosona (C33H42O4, MM= 502 g/mol), uma benzofenona prenilada. A concentração inibitória mínima da nemorosona foi de 6,25 ¿ 12,5 ?g/mL e na concentração de 100 ?g/mL foi capaz de inibir em 95% a aderência do S. mutans em biofilme formado em microplacas de fundo côncavo. Em biofilme formado em discos de hidroxiapatita, a nemorosona na concentração 250 ?g/mL (0,50 mM) reduziu 65 % do peso seco, mais de 70% dos polissacarídeos e 48% da quantidade proteica além de diminuir a viabilidade bacteriana, quando comparada com o controle negativo (veículo, p<0,05). Estes resultados não diferiram estatisticamente da clorexidina a 0,12% (1,33 mM) (p>0,05). Portanto, concluímos que a nemorosona é um composto ativo isolado e identificado da geoprópolis com atividade antibiofilme de S. mutans com capacidade de alterar a composição bioquímica da matriz do biofilme de S. mutans, o que torna este composto promissor agente químico para o controle do biofilme oral / Abstract: Natural products have been demonstrated a promising source to discover new bioactive compounds. Among then, the propolis collected by Apis mellifera bees has biological activity described in the literature as anticairies, antimicrobial, anti-inflammatory, besides other activities. However, most of the studies on propolis refer to those collected by A. mellifera and little is known about others as geopropolis, which is collected by stingless bees of the genus Melipona. In recent studies, geopropolis presented promising antimicrobial and anti-inflammatory activities, but these studies have not revealed which is (are) the substance(s) responsible(s) for such biological activities, especially against the cariogenic oral biofilms. Therefore, the objective of this study was to isolate and identify the active compound from Melipona scutellaris geopropolis, which has activity against the biofilm formation by Streptococcus mutans. This goal was achieved by the following methodologies: 1- bioassay-guided fractionation of the goeporpolis ethanolic extract (EEGP); 2- isolation and identification of the active compound; 3- anticarie potential assessment of the active compound using an in vitro model of inhibition of the oral mono-species biofilm. As result of the bioassay-guided fractionation, the poliprenil benzophenone compound named nemorosone (C33H42O4, MW=502 g/mol) was isolated and identified. The nemorosone¿s minimum inhibitory concentration (MIC) was 6.25 ¿ 12.5 ?g/mL and the concentration of 100 ?g/mL was capable to inhibit by 95% the adherence of S. mutans¿s biofilm formed in U-bottom microtiter plates. In biofilm formed in hydroxyapatite disks, the nemorosone concentration of 250 ?g/mL (0.5 mM) reduced 65% of the dry weight, more than 70% of the polysaccharides and 48% of the protein content. In addition, it reduced the bacterial viability when compared to negative control (vehicle, p<0.05). These results did not differ statistically from chlorhexidine 0.12% (1.33 mM) (p> 0.05). Therefore, the conclusion is that nemorosone is the active compound isolated and identified from geopropolis with antibiofilm activity that is able to alter the biochemical composition of the S. mutans biofilm matrix, it makes this chemical compound promising to oral biofilm control / Mestrado / Farmacologia, Anestesiologia e Terapeutica / Mestra em Odontologia

A search of the literature revealed few references to the normal enteric flora of non-human vertebrates in general and the llama, Lama glama, in particular. The bacteriologic flora of the llama as a research project was suggested by my major professor, Dr. Fuad M. Nahhas, after it was brought to his attention by one of his assistants in the microbiology department of Dameron Hospital (Stockton, CA) that her pet llama was suffering from diarrhea. Fecal material from the llama was cultured and Yersinia enterocolitica was recovered. At the same time normal bacterial flora resembling those isolated from human material were also found. In seeking a research project I thought a bacteriologic examination of fecal material from llamas would be of some interest. A search of the literature revealed a great deal of information about parasitic infections of the llama, particularly by South American parasitologists and veterinarians,. but little information on the bacteriologic flora. Most of the published reports discuss enteric pathogens and enteric diseases (Fowler, 1989). Equally scarce are reports on the antibiotic pattern of such isolates; most reports on antimicrobial activity are limited to determining which drugs are effective in the treatment of a particular infection (Timoney et al, 1988). In contrast with this, Gram negative isolates from human intestinal material are well known and their antibiograms well documented in the literature as well as in unpublished hospital records. The use of antibiotics, discriminately or indiscriminately, in the treatment of human infections and the addition of antibiotics, especially tetracycline, to animal feeds to promote growth have led to the emergence··of resistant strains among these bacteria. To what extent such resistance exists in, has crossed over to, or has been exchanged among the intestinal isolates of humans and other vertebrates is not known. The objective of this study is, therefore, twofold: 1) to conduct a survey of the Gram negative aerobic intestinal bacterial flora of llamas to determine what species are present and their relative abundance; 2) to compare their biochemical (biotypes) and antibiotic patterns (antibiogram) with isolates from other animals and humans where information is available.

The development and evaluation of a vancomycin population pharmacokinetic model in children, pre-adolescent, and adolescent patients was performed via non linear mixed effects modeling (NONMEM) in 2 phases. In phase I, a vancomycin population pharmacokinetic model was developed based on data from 200 children (aged 2-17 years) using a two-compartment model. Variables tested for inclusion in the model were serum creatinine (SCR), age (AGE), weight (WT), height (HT), sex (SEX), and body surface area (BSA). Variables were included at the p $ In phase II, the performance of the derived model was evaluated in a naive tested population and then compared to the Schaad, et al. model via prediction error techniques (PE). The predictability of 159 measured concentrations was assessed in 68 new patients. In predicting all concentrations types, the mean prediction error (MPE) with a 95% confidence interval (CI) for both the current study model and Schaad, et al model were: $-$1.42 ($-$3.38, 0.54), and 6.01 (4.46, 7.56) mg/L, respectively. When considering only peaks, a MPE with 95% CI were 1.72 ($-$0.94, 4.38), and 7.61 (5.13, 10.09) mg/L, respectively. Finally, MPE with 95% CI for the troughs were $-$1.45 ($-$3.42, 0.52), and 3.84 (2.98, 4.70) mg/L, respectively. Maintenance dose (MD) tables were designed, based on the relationship of height and serum creatinine to clearance. In addition, a loading dose (LD) was also recommended, which was 5 mg/cm. It is recommended that the current study model be used for dosing the pediatric population while setting an initial target peak of 30 mg/L and a trough of 5-10 mg/L. This should frequently result in optimal serum vancomycin concentrations within the therapeutic window. Individualization of therapy should then be done, once the measured concentrations are available.

No description available.

<p> This thesis describes the isolation and structural determination of flavonoids from the heart wood of Prunus avium as well as synthesis of polyhydroxy pyrrolidine derivatives and aniline core structures as potential antibacterial agents. Nitrogen-synthons containing saturated heterocyclic systems and aniline core structures are important synthons in organic chemistry because of their presence in many biologically-active natural products. Mycobacterial viability is dependent upon the ability of the organism to produce an intact cell wall. Therefore, compounds that interfere with the biosynthesis of the cell wall complex glycons have the potential to become new drugs for the treatment of mycobacterial infections. The oligosaccharide galactan is one of the major structural components of the outer wall of the micro-organism. Galactofuranose is essential for cell growth and survival and therefore, its biosynthesis constitutes a new drug target. The biosynthetic process involves several enzymes having Uridine-diphosphogalacto furanose (UDP-Galf) as the substrate; uridine 5^1 -diphosphogalacto pyranose mutase which catalyzes the interconversion of UDP galacatopyranose to UDP-galactofuranose as well as Galf-transferase. We are seeking and designing molecules that could be mechanistic probes and/or inhibitors of efflux pumps to potentially combat multidrug resistance.</p> <p> The isolation and structure-determination of six naturally occurring Flavan-type Natural products was performed. Such derivatives are known to reverse multiple-drug-resistance (MDR) in persistent microbial infections. The synthesis of pyrrolidine-based antibacterial agents was attempted using two different approaches from tartaric acid. These derivatives were designed as potential transition-state mimics of a carbohydrate processing enzyme specific to TB. A synthetic approach to the aromatic core structure of the antibacterial agent Platensimycin was also investigated. The synergistic use of cytotoxic agents in conjunction with efflux-pump modulators is an emerging area of research in the MDR field; our efforts to make available materials for high-throughput screening in this area will be described.</p> / Thesis / Master of Science (MSc)

Metal oxide-facilitated transformation is likely an important degradation pathway of antibacterial agents at soil-water interfaces. Phenolic disinfectants (triclosan and chlorophene), fluoroquinolones (FQs), and aromatic N-oxides are of particular concern due to their widespread usage, potential toxicity and frequent detection in the environment. Results of the present study show that the above antibacterial agents are highly susceptible to metal oxide-facilitated oxidation. The interfacial reactions exhibit complex reaction kinetics, which are affected by solution pH, the presence of co-solutes, surface properties of metal oxides, and structural characteristics of antibacterial agents. Adsorption of the antibacterial agents to Mn and Fe oxide surfaces generally proceeds faster than oxidation reactions of these compounds by Mn and Fe oxides, especially in the case of Fe oxides. Reaction intermediates and end products are identified by GC/MS, LC/MS and/or FTIR. Structurally-related model compounds are examined to facilitate reaction site and mechanism elucidation. On the basis of experimental results and literature, reaction schemes are proposed. In general, the antibacterial agent is adsorbed to the oxide surface, forming a precursor complex. Electrons are transferred within the precursor complex from the antibacterial agent to the oxide, followed by releasing of the radical intermediates which undergo further reactions to generate oxidation products. The precursor complex formation and electron transfer are likely rate-limiting. For triclosan, phenoxy radicals are critical intermediates to form oxidation products through three pathways (i.e., radical coupling, further oxidation of the radical, and breakdown of an ether bond within the radical). The first two pathways are also operative in the oxidation of chlorophene. For FQs, oxidation generates radical intermediates that are most likely centered on the inner N in the piperazine ring. The radical intermediates then undergo three major pathways (i.e., radical coupling, N-dealkylation, and hydroxylation) to yield a variety of products. For aromatic N-oxides, a N-oxide radical intermediate is generated upon oxidation by MnO2, followed by the loss of oxygen from the N-oxide moiety and the formation of a hydroxyl group at the C-atom adjacent to the N-oxide moiety. Overall, a fundamental understanding of the reaction mechanisms between three classes of antibacterial agents and metal oxides has been obtained.

Submitted in complete fulfillment for the Degree of Master of Technology: Biotechnology, Durban University of Technology, Durban, South Africa, 2014. / Antibiotic resistance amongst bacterial pathogens is a crisis that has been worsening over recent decades, resulting in serious and often fatal infections that cannot be treated by conventional means. Diseases caused by these drug resistant agents result in protracted illnesses, greater mortality rates and increases in treatment costs. Improvements to existing therapies and the development of novel treatments are urgently required to deal with this escalating threat to human health. One of the more promising strategies to combat antibiotic resistance is the use of metallic nanoparticles. Research into this area has shown that the binding of antibiotics to nanoparticles enhances their antimicrobial effects, reduces side-effects due to requirement of lower dosages of the drug, concentrates the drug at the interaction site with bacterial cells and in certain cases, has re-introduced susceptibility into bacterial strains that have developed drug resistance. Furthermore, these nanoparticles can be used in cancer treatment in similar drug delivery roles. Based on the promising data that demonstrated the synergistic effects of antimicrobial agents with nanoparticles, the aim of our research is to determine the effect of ciprofloxacin-conjugated gold nanoparticles as antimicrobial agents. To achieve this aim our objectives were: (i) to synthesize citrate-capped and ciprofloxacin-conjugated gold nanoparticles; (ii) to determine the physical and chemical characteristics of the ciprofloxacin-nanoparticle hybrid molecule; (iii) to investigate the antimicrobial activity of the conjugated nanoparticles against various species of common pathogens and (iv) to investigate the anti-cancer potential of the citrate-capped nanoparticles against a Caco-2 cell line. In this study, citrate-capped gold nanoparticles were conjugated to the antibiotic, ciprofloxacin, and their antibacterial and anti-cancer activity was evaluated. Initial experiments involved the synthesis and characterization of gold nanoparticles and ciprofloxacin conjugated nanoparticles. The gold nanoparticles were synthesized using the Turkevich citrate reduction technique which has been extensively used in studies thus far. The synthesized nanoparticles were characterized for specific absorbance using a UV-Spectrophotometer. The bond between the nanoparticles and ciprofloxacin was characterized by FTIR. Ultra structural details of the gold nanoparticles were established by TEM. The colloidal stability of the nanoparticles was determined by spectroscopic analysis. The antibacterial activity of the ciprofloxacin-conjugated gold nanoparticles was studied by exposure to pathogenic bacteria (Staphyloccocus aureus, E. coli, Klebsiella pneumoniae, Enterocococcus spp., Enterobacter spp., and Psuedomonas spp.). MIC values were measured to give indication of antimicrobial effect. These bactericidal properties of the conjugate nanoparticles were further investigated by electron microscopy. To evaluate the action of the citrate capped gold nanoparticles on cancer cells, we exposed Caco-2 cells to various concentrations of the nanoparticles and its effect was evaluated by measuring the viability of the cells. The results showed that 0.5 mM trisodium citrate reduced gold chloride to yield gold nanoparticles, which were spherical and 15 to 30 nm (by TEM characterization) and had an absorption maxima of 530 nm. The ciprofloxacin conjugated nanoparticles had an absorption maxima of 667nm. The colloidal stability, which is used to assess whether the synthesized particles will retain their integrity in solution showed that citrate-capped GNPs were most stable at 37°C over a 14 day storage period while ciprofloxacin-conjugated GNPs were found to be most stable at 4°C over a 14 day period. The FTIR results showed that chemical bonding in the conjugated nanoparticles occurs between the pyridone moiety of ciprofloxacin and the nanoparticle surface. The antimicrobial results of ciprofloxacin-conjugated GNPs had a significantly improved killing response compared to ciprofloxacin on both Gram positive and Gram negative bacteria. The citrate-capped GNPs are shown to exert a similar cytotoxic effect to gemcitabine on the Caco-2 cell line at a concentration of 0.5 mM. These results indicate that combining gold nanoparticles and ciprofloxacin enhances the antimicrobial effect of the antibiotic. The conjugate nanoparticles increase the concentration of antibiotics at the site of bacterium-antibiotic interaction, and thus enhance the binding and entry of antibiotics into bacteria. This has great implications for treatment of infection, as these antibiotic-conjugated nanoparticles can be incorporated into wound dressings, be administered intravenously as drug delivery agents, be engineered to possess multiple functionalities in addition to antibacterial activity and act as dual infection tracking and antimicrobial agents. Likewise, in this study, gemcitabine, an anticancer drug and gold nanoparticles were shown to kill cancer cells. In addition to their use in photothermal therapy and as drug delivery agents, the nanoparticles themselves possess anti-cancer activity against the Caco-2 cells. Thus, they have potential to act alone as a form of cancer treatment if functionalized with certain targeting agents that are specific to cancer cells, reducing the side-effects that come with regular chemotherapeutic drugs. It can be concluded that ciprofloxacin-conjugated gold nanoparticles enhance antibacterial effects of the antibiotic ciprofloxacin against bacterial cells and citrate-capped gold nanoparticles have anti-cancer activity against the Caco-2 cell line.