A significant potion of the population in Lesotho relies on traditional medicine to meet its health care requirements. Traditional healers and herbalists were interviewed from Qacha's Nek (Highlands) and Mohale's Hoek (Lowlands) districts in Lesotho on plants used by the Basotho in traditional remedies. Fifteen plants were reported to be used for bacterial infections while thirteen plants were used for diseases associated with inflammation . Plant roots were most often used to make water extracts. Mainly high altitude plants are used with lowland healers obtaining most of their plant material from the highlands, either by collecting them or buying them from highland gatherers. Leaves and roots of plants used to treat bacterial infections were extracted with hexane, methanol and water and the respective extracts screened at 100 mg ml¯¹ for anti-bacterial activity using the disc diffusion bioassay. Seven species displayed very high anti-bacterial activity against both Gram-positive and Gram-negative bacteria. A number of plant extracts had medium inhibitory activity, mostly against Gram-positive bacteria. This activity was mainly found in the root extracts. Six of the thirteen plants screened for anti-inflammatory activity using the cyclooxygenase-1 (COX-1) bioassay had activity above 90%. Hexane and methanol extracts were the most active while water extracts usually had lower activity. Malva parviflora, Eriocephalus punctulatus and Asparagus microraphis exhibited high anti-inflammatory activity from hexane, methanol and water extracts made from leaf and root material. High anti-bacterial activity was also recorded from M. parviflora and E. punctulatus hexane, methanol and water extracts. An investigation on seasonal variation and plant part substitution in medicinal activities for these plants was carried out. Extracts of M. parviflora collected between June 1999 and July 2001 showed variation in anti-bacterial activity. Extracts made from leaves and roots inhibited the growth of both Gram-positive and Gram-negative bacteria. More bacterial strains were inhibited by extracts made from roots collected in cooler months. However, a trend in seasonal activity was not evident for either the roots or leaves because there was no detection of activity in some of the extracts made within the same months or seasons of the adjacent years. Variation in anti-inflammatory was detected for M. parviflora extracts. E. punctulatus leaf extracts did not exhibit any seasonal variation in anti-bacterial activity. Anti-inflammatory activity of E. punctulatus showed seasonal variation with the highest activity noted when material was collected during the cooler months and a decline in activity when collections were made during the warmer months. Hexane, methanol and water extracts made from leaves and roots of A. microraphis did not show any seasonal variation in anti-inflammatory activity. Thus, M. parviflora and E. punctulatus should be collected during the cooler months while A. microraphis can be collected throughout the year. Traditional healers, herbalists and vendors need to be encouraged to use aerial parts in substitution of ground parts which are reported to be highly utilized. Effect of storage on anti-bacterial and anti-inflammatory activities of M. parviflora, E. punctulatus and A. microraphis were monitored. Dried, ground leaf and root material of the three plants was stored in a cold room, at room temperature and in the Botanical Garden where the material was exposed to high and large changes in temperature. Dried hexane and methanol extracts made from leaves and roots of these plants were stored in a cold room and at room temperature. Initially, storage of the plant material under the three storage conditions caused an increase in antibacterial activity of the hexane, methanol and water extracts made from leaf and root material of M. parviflora and E. punctulatus. Storage for a longer period resulted in a decrease in inhibitory activity. TLC fingerprints developed from hexane and methanol extracts made from M. parviflora and E. punctulatus stored in a cold room and at room temperature showed a consistent number and colour of spots during the initial storage period. Prolonged storage resulted in a decline in the number and colour of detected spots. The stored hexane and methanol extracts made from leaves and roots showed a similar trend of increases and decreases in anti-bacterial activity as well as changes in spots with the storage of the extracts. Testing of the effect on anti-inflammatory activity of hexane, methanol and water extracts made from leaves and roots of M. parviflora, E. punctulatus and A. microraphis showed no change in inhibitory activity of hexane extracts obtained from the material and the extracts stored at the three storage conditions. Methanol and water extracts made from leaves exhibited an increase in activity with prolonged storage. Generally, the stability of the inhibitory activity was longer for the stored dried material than the plant extracts. Isolation of biological active compounds from M. parviflora was not successful due to loss in anti-bacterial activity as a result of collection of plant material from a different locality. Anti-inflammatory compounds could not be isolated due to insufficient amount and the synergistic effect of the active compounds . The purified compounds exhibited loss of activity following HPLC purification which then re-appeared upon recombining the fractions. A number of compounds were detected from essential oils of E. punctulatus using GC. Fractions containing these compounds gave positive anti-bacterial activity in the disc-diffusion , bioautographic and MIC bioassays as well as high anti-inflammatory activity with COX-1 and COX-2 anti-inflammatory bioassays. No anti-inflammatory compounds were isolated from A. microraphis. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2003.

The use of mouthwash is a common complement to oral care. However, the physiological implication of this use, besides of effects on oral hygiene, is poorly known. The research of the gut micro flora and its implications on the host is a very active area of research today. Many important connections between the gut micro flora and obesity and diabetes have been found. These billions of bacteria are part of the immune system, they produce essential vitamins and they make inaccessible polysaccharides more digestible to the host, just to mention a few of their symbiotic roles for the host. A less explored area is the micro flora in the oral cavity. On the back of the tongue, anaerobic bacteria can reduce dietary nitrate to nitrite which then further can be reduced to nitric oxide, NO. NO is important in several important biological functions, e.g. as a signal substance, vasoregulation, mucus production and antibacterial effects. Vegetables as beetroot and spinach are dietary sources with a high nitrate content. Also drinking water and processed meats can be of relevance. Nitrite is added to processed meat for the prevention of botulism but also adds taste and color.   Experiments on humans indicate that mitochondrial efficiency increases after nitrate load, manifested as a decreased oxygen demand during physical exercise. This can also be relevant under conditions where the mitochondrial function is impaired, such as in diabetes and cardiovascular diseases. First a pilot study was made to evaluate the nitrate reducing effect from the antibacterial mouthwash. The mouthwash proved very effective. The concentrations of nitrate and nitrite in saliva was analyzed by HPLC and saliva from the antibacterial treatment showed greatly reduced concentrations of nitrite and high concentrations of nitrate. Saliva from placebo mouthwash showed high concentrations of nitrite and low concentrations of nitrate as expected. To study the importance of oral bacteria on metabolism, we performed a randomized, cross-over double-blinded study with 19 healthy males between 22-43 years. During two separate three-day periods they used an antibacterial and placebo mouthwash, respectively. On the fourth day their basal metabolic rate (BMR) was measured with an indirect calorimetric system. Moreover, samples from saliva, urine and blood were collected but these results are not included in this thesis. An earlier, unpublished study has demonstrated that nitrate administration reduces the basal metabolic rate. Accordingly, our aim was to study potential effects on the basal metabolic rate following reduction of the number of oral bacteria by aid of antibacterial mouthwash. Our hypothesis was that the reduced availability of nitrite would decrease the availability of NO in the body and manifest as an increased basal metabolic rate. The results from indirect calorimetry measurements showed no significant difference between placebo and antibacterial mouthwash, but there may be confounding factors. Further study is needed to assess the potential effects on host metabolism by these bacteria.

Titanium and titanium based alloys are widely used in dentistry and orthopedics to replace hard tissue and to mend broken bones. It has become a material of choice due to its low density, high strength, good biocompatibility and its capacity to integrate closely with the bone. Today, modern materials and surgical techniques can enable patients to live longer, and aid in maintaining or regaining mobility for a more fulfilling life. There are, however, instances where implants fail, and one of the primary causes for implant failure is infection. This thesis deals with two possible ways of reducing or eliminating implant associated infections; TiO2 photocatalysis, where a surface can become antibacterial upon irradiation with UV light; and incorporation of silver, where a subsequent release of silver metal ions result in an antibacterial effect. For the TiO2 photocatalysis strategy, a simple and cost effective chemical oxidation technique, using hydrogen peroxide (H2O2) and water, was used to create an active TiO2 surface on titanium substrates. This surface was shown to effectively degrade an organic model substance (rhodamine B) by generating reactive oxygen species (ROS) under UV illumination. However, it was shown that Ti-peroxy radical species remaining in the surface after the H2O2-oxidation process, rather than generation of ROS from a heterogeneous photocatalytic process, was responsible for the effect. This discovery was further exploited in a TiO2/H2O2/UV system, which demonstrated synergy effects in both rhodamine B degradation tests and in antibacterial assays. For the silver ion release strategy, a combinatorial materials science approach was employed. Binary Ag-Ti oxide gradients were co-deposited in a reactive (O2) environment using a custom built physical vapor deposition system, and evaluated for antibacterial properties. The approach enabled synthesis and composition-structure-property evaluation unlikely to have been achieved by traditional means, and the gradient coatings demonstrated antibacterial properties against both S. aureus and S. epidermidis according to silver ion release. The release was shown to depend more on structural features, such as surface area, crystallinity and oxidation state, than on composition. Ag-Ti oxide gradients were also evaluated under UV illumination, as Ag deposits on crystalline TiO2 can enhance photocatalytic properties. In this work, however, the TiO2 was amorphous and UV illumination caused a slight reduction in the antibacterial effect of silver ions. This was attributed to a UV-induced SOS response in the S. epidermidis bacteria. The results of this thesis demonstrate that both TiO2 photocatalysis, or UV induced activation of Ti-peroxy radical species, as well as incorporation of silver are viable antibacterial strategies for titanium biomaterials. However, their clinical applications are still pending risk-benefit analyses of potential adverse host tissue responses.

Bacterial resistance to antibiotics is an emerging epidemic throughout the world and there is a desperate need for new antibiotics and new strategies to maintain the effectiveness of current agents. ??-Lactams, such as the penicillins and cephalosporins, have been the most important class of antibiotic for several decades and represent half of the global antibacterial market, but the continued use of ??-lactams is threatened by ??-lactamases, enzymes that efficiently inactivate ??-lactams through hydrolysis. Class A, C, and D ??-lactamases use an active-site serine residue for hydrolysis and achieve turnover through an acylenzyme intermediate while the class B metallo-??-lactamases (MBLs) use a zinc-bound hydroxide as the active-site nucleophile. Two successful approaches to combat ??-lactamase-mediated resistance have involved the development of ??-lactam antibiotics which bind poorly to ??-lactamases and the combination of ??-lactams with ??-lactamase inhibitors. These strategies have been effective for overcoming resistance due to class A ??-lactamases, but the ever-increasing prevalence of extended-spectrum ??-lactamases (ESBLs), metallo-??-lactamases, and carbapenemases compromises the effectiveness of current penicillins, cephalosporins, carbapenems, and mechanism-based ??-lactamase inhibitors. Cyclobutanone analogues of ??-lactam antibiotics were explored in the early 1980s as potential inhibitors of ??-lactamases and D-Ala-D-Ala transpeptidases, but simple analogues showed only weak inhibitory activity and this approach was subsequently abandoned. The increasing threat of multidrug-resistant ??-lactamase-producing organisms in recent years, however, has inspired a re-evaluation of these inhibitors since cyclobutanones have the potential to exhibit broad-spectrum inhibition of both serine- and metallo-??-lactamases through the formation of enzyme-bound hemiketals or hydrates. 7,7-Dichloro-2-thia-bicyclo[3.2.0]heptan-6-one-4-carboxylic acid (65), a dichlorocyclobutanone that had shown modest inhibition of the class B and D ??-lactamases IMP-1 and OXA-10 in earlier work in this laboratory, was prepared in an efficient seven-step sequence from triethyl phosphonoacetate (103) with an overall yield of 28%. Initial efforts to improve upon the potency of the cyclobutanones involved functionalization at C3 and a highly stereoselective chlorination with sulfuryl chloride provided the 3??-chloro derivative 117?? in nearly quantitative yield. Elimination of HCl from 117?? was achieved under a variety of conditions and 3-alkoxy derivatives were prepared from 117?? through diastereoselective substitution reactions with alcohols. Cyclobutanones with 3??-OR substituents were found to favour an endo envelope conformation while the 3??-OR derivatives adopt the exo envelope conformation. Evidence from X-ray crystal structures and ab initio molecular orbital calculations suggests that an anomeric effect contributes to the large conformational preference of the tetrahydrothiophene ring that favours the 3-alkoxy substituent in an axial orientation. In addition, the conformation of the bicyclic system was found to have a dramatic effect on the tendency of the cyclobutanone to undergo hemiketal formation. Cyclobutanone analogues of penicillins, including 3-alkoxy derivatives, and cyclobutanone analogues of penems were evaluated against class A, B, C, and D ??-lactamases and found to be moderate inhibitors of KPC-2, IMP-1, GC1, and OXA-10. The cyclobutanones found to be most potent were those which are hydrated to a larger extent in aqueous solution. Dichlorocyclobutanones were found to be better inhibitors than dechlorinated cyclobutanones and a 3??-methoxy derivative 152??, which favours the exo envelope conformation in which the C4 carboxylate is equatorial, was found to be a better inhibitor than cyclobutanones that favour the endo envelope conformation. A 3,4-unsaturated penem analogue, 153, showed comparable potency to that of 152?? and molecular models of enzyme-inhibitor complexes indicate that an equatorial carboxylate is required for binding to ??-lactamases. An X-ray crystal structure of 152?? bound to the class D ??-lactamase OXA-10 confirms that a serine hemiketal is formed in the active site and that the inhibitor adopts the exo envelope. The biochemical data described above demonstrate that cyclobutanones can indeed act as inhibitors of serine- and metallo-??-lactamases and these cyclobutanones represent the first class of reversible inhibitors to show moderate inhibition of all four classes of ??-lactamase. Although the inhibitory potency of these compounds is modest (low micromolar IC50 values), penem analogue 153 was able to enhance the potency of meropenem against carbapenem-resistant MBL-producing clinical isolates of Chryseobacterium meningosepticum and Stenotrophomonas maltophilia and the synergy demonstrated in these antimicrobial assays is encouraging. Synthetic studies toward other C3-alkyl and C3-thioalkyl-substituted inhibitors are described and the design and synthesis of C7-monochloro- and 7??-hydroxymethyl-7??-chloro cyclobutanone derivatives is presented.

OBJECTIVE: To measure urinary triclosan levels and their variability across pregnancy, and to identify sources of triclosan exposure among Canadian pregnant women. METHODS: Single spot and serial urine samples, as well as consumer product use information were collected across pregnancy and post-partum from 80 healthy pregnant women in Ottawa. Analyses included descriptives, linear mixed effects and parametric trend modeling, and surrogate category analysis. RESULTS: Triclosan was detected in 87% of maternal urine samples (LOD=3.0 µg/L). Triclosan concentrations varied by time of day of urine collection (p=0.0006), season of sampling (p=0.019), and parity (p=0.038). Triclosan was included in 4% of all personal care products used by participants; 89% of these triclosan products were varying brands of toothpaste and hand soaps. CONCLUSION: This study provided the first data on temporal variability urinary triclosan levels, and on source attribution data in Canadian pregnant women. Results will assist with population-specific exposure assessment strategies.

Klinikinėje praktikoje infekcinėms ligoms gydyti vartojama daugiau kaip 200 priešmikrobinių medžiagų, tačiau infekcinės ligos yra viena dažniausių mirties priežasčių ir naujų priešmikrobinių vaistų poreikis nemažėja. Modifikuojant 4-tiazolidinono žiedą susintetinami įvairaus biologinio aktyvumo junginiai. 4-tiazolidinono dariniai su sulfanilamido farmakoforu yra aktyvesni už sulfanilamidus prieš bakterijas ir pasižymi priešgrybeliniu poveikiu; su nitrofurano farmakoforu yra vieni aktyviausių priešmikrobinių junginių. Alilaminą įjungus į molekulę kartu su jau anksčiau žinomais farmakoforais, tikėtąsi geresnio naujų junginių priešmikrobinio aktyvumo. Pritaikius pasirinktas metodikas naujų 4-tiazolidinono darinių su pasirinktų farmakoforų (sulfanilamido, nitrofurano, alilamino) struktūriniais fragmentais sintezei, susintetinti 39 4-tiazolidinono ciklą turintys junginiai. Įvertinus fiziko-chemines savybes ir toksiškumo riziką in silico, nustatyta junginių, kaip biologiškai aktyvių medžiagų, vertė. In silico ir in vitro patvirtinta, kad nauji 4-tiazolidinono dariniai su sulfanilamido, nitrofurano ir alilamino farmakoforais pasižymi prieš¬mikrobinėmis savybėmis prieš skirtingas bakterijų (S. aureus, E. faecalis, E. coli, P. aeruginosa, K. pneumonia, B. subtilis, P. mirabilis) ir grybelio C.albicans kultūras. Apibendrinus mikrobiologinių tyrimų rezultatus, nustatyti aktyviausi antibakteriniai ir priešgrybeliniai junginiai. / More than 200 antimicrobial agents are used in clinical practice for the treatment of infectious diseases, however, infectious diseases are still one of the most common causes of death, and the need for new antimicrobials isn’t decreasing. Compounds with different biological activity are synthesized by modifying 4-thiazolidinone. 4-thiazolidinones with sulfanilamide pharmacophore are more active against bacteria than sulfanilamides, and are characterized as antifungals. 4-thiazolidinones with nitrofuran pharmacophore are one of the most active antimicrobials. Higher antimicrobial activity of new compounds was expected after attaching allylamine to the molecule together with the previously known pharmacophores. By applying the selected methodologies for the synthesis of new 4-thiazolidinones with the fragments of selected pharmacophores (sulfanilamide, nitrofurane, allylamine), 39 derivatives of 4-thiazolidinone were synthesized. The assessment of physico-chemical properties and toxicity risk in silico helped to determine the value of compounds as biologically active substances. In silico and in vitro studies confirmed that new 4-thiazolidinone’s with sulfanilamide, nitrofurane and allylamine pharmacophores showed antimicrobial activity against various bacteria (S. aureus, E. faecalis, E. coli, P. aeruginosa, K. pneumonia, B. subtilis, P. mirabilis) and fungal cultures of C.albicans. Summarising microbiological tests, the most active antibacterial and antifungal compounds... [to full text]

Klinikinėje praktikoje infekcinėms ligoms gydyti vartojama daugiau kaip 200 priešmikrobinių medžiagų, tačiau infekcinės ligos yra viena dažniausių mirties priežasčių ir naujų priešmikrobinių vaistų poreikis nemažėja. Modifikuojant 4-tiazolidinono žiedą susintetinami įvairaus biologinio aktyvumo junginiai. 4-tiazolidinono dariniai su sulfanilamido farmakoforu yra aktyvesni už sulfanilamidus prieš bakterijas ir pasižymi priešgrybeliniu poveikiu; su nitrofurano farmakoforu yra vieni aktyviausių priešmikrobinių junginių. Alilaminą įjungus į molekulę kartu su jau anksčiau žinomais farmakoforais, tikėtąsi geresnio naujų junginių priešmikrobinio aktyvumo. Pritaikius pasirinktas metodikas naujų 4-tiazolidinono darinių su pasirinktų farmakoforų (sulfanilamido, nitrofurano, alilamino) struktūriniais fragmentais sintezei, susintetinti 39 4-tiazolidinono ciklą turintys junginiai. Įvertinus fiziko-chemines savybes ir toksiškumo riziką in silico, nustatyta junginių, kaip biologiškai aktyvių medžiagų, vertė. In silico ir in vitro patvirtinta, kad nauji 4-tiazolidinono dariniai su sulfanilamido, nitrofurano ir alilamino farmakoforais pasižymi prieš¬mikrobinėmis savybėmis prieš skirtingas bakterijų (S. aureus, E. faecalis, E. coli, P. aeruginosa, K. pneumonia, B. subtilis, P. mirabilis) ir grybelio C.albicans kultūras. Apibendrinus mikrobiologinių tyrimų rezultatus, nustatyti aktyviausi antibakteriniai ir priešgrybeliniai junginiai. / More than 200 antimicrobial agents are used in clinical practice for the treatment of infectious diseases, however, infectious diseases are still one of the most common causes of death, and the need for new antimicrobials isn’t decreasing. Compounds with different biological activity are synthesized by modifying 4-thiazolidinone. 4-thiazolidinones with sulfanilamide pharmacophore are more active against bacteria than sulfanilamides, and are characterized as antifungals. 4-thiazolidinones with nitrofuran pharmacophore are one of the most active antimicrobials. Higher antimicrobial activity of new compounds was expected after attaching allylamine to the molecule together with the previously known pharmacophores. By applying the selected methodologies for the synthesis of new 4-thiazolidinones with the fragments of selected pharmacophores (sulfanilamide, nitrofurane, allylamine), 39 derivatives of 4-thiazolidinone were synthesized. The assessment of physico-chemical properties and toxicity risk in silico helped to determine the value of compounds as biologically active substances. In silico and in vitro studies confirmed that new 4-thiazolidinone’s with sulfanilamide, nitrofurane and allylamine pharmacophores showed antimicrobial activity against various bacteria (S. aureus, E. faecalis, E. coli, P. aeruginosa, K. pneumonia, B. subtilis, P. mirabilis) and fungal cultures of C.albicans. Summarising microbiological tests, the most active antibacterial and antifungal compounds... [to full text]

Darbo tikslas – sintetinti potencialius antibakterinius ir priešgrybelinius 3-amino rodanino darinius su pakaitais 3-oje ir 5-oje padėtyse bei ištirti jų struktūros įtaką aktyvumui. Tyrimo metodai – junginių antimikrobinio ir priešgrybelinio aktyvumo bei toksiškumo prognozė atlikta naudojant PASS programą. Antimikrobinis ir priešgrybelinis aktyvumas tirtas in vitro serijinio skiedimo standžioje terpėje metodu. Tyrimo rezultatai – PASS programa priešgrybelinį aktyvumą prognozavo visiems junginiams didesne tikimybe nei antibakteriniam. Pastarojo neprognozavo trims junginiams. Junginiams, kuriems prognozuotas didžiausias aktyvumas – tikimybė būti toksiškiems taip pat buvo didžiausia. Atlikus tyrimus in vitro paaiškėjo, kad nitrofurano liekana smarkiai padidina 3-amino rodanino aktyvumą prieš tiriamas organizmų kultūras. Radikalo įjungimo vieta į 3-amino rodanino žiedą daro svarbią įtaką aktyvumui: aktyviausi junginiai turi pakaitus trečioje padėtyje, o neaktyvūs – penktoje. 3-amino rodanino žiedo išskleidimas įvedant pakaitą per amino grupę padidino priešgrybelinį veikimą. Gauti rezultatai parodė, kad aromatinių benzaldehidų įtaka aktyvumui priklauso nuo pakaitų pobūdžio ir vietos juose. Išvados – aktyvumo programa PASS gali padėti iš anksto tikėtis rezultato ir pagal tai kryptingai pasirinkti junginius, tačiau būtina atlikti tyrimus ir in vitro. 3-amino rodanino darinių aktyvumas priklauso nuo pakaitų įvedimo padėties. Atsižvelgiant į gautus rezultatus, išskirti... [toliau žr. visą tekstą] / Aim of study – synthesize potential antibacterial and antifungal 3-amino rhodanine compounds with substitutes in 3 and 5 places and analyze their structure influence to the activity. Study methods – prognosis of antifungal, antibacterial and toxicity of synthesized compounds was made by PASS program. Antibacterial and antifungal activity was tested in vitro by serial dilution in stiff environment. Study results – PASS program predicted antifungal activity to all compounds with higher probability than antifungal. 3 compounds had no predictions to antibacterial activity. According to PASS results, the most active compounds could be the most toxic. Research in vitro showed, that moiety of nitrofuraldehyde increases activity of 3-amino rhodanine against microbes and fungi cultures. Activity depends on the place of derivative in the ring of 3-amino rhodanine: the most active compounds had derivatives in 3rd place, and inactive – in 5th. Opening of the ring of 3-amino rhodanine during reaction in 3rd place increased antifungal activity. Results showed, that the influence of aromatic benzaldehydes to the activity depends on derivatives nature and place in aldehydes. Conclusions – activity program PASS could help predict result and accordingly choose compounds. However it is necessary to perform studies in vitro. Activity of 3-amino rhodanine compounds depends on derivatives place in the ring. With respect to results in vitro, 2 most active compounds were sorted: EK-1 and EK-14 which... [to full text]

Traditional bacterial disease therapies utilize compounds that ultimately kill the target bacteria but it exerts a strong selective pressure on the bacteria to develop multi-drug resistance mutants. The increasing occurrence of resistance in common pathogens has highlighted the need to identify new anti-microbials that target the control of bacterial pathogenicity in a non-extermination manner to reduce the incidence of bacteria resistance. One new strategy exploits the discrete signaling molecules that regulate the various bacterial signaling pathways, which are responsible for the expression of pathogenicity traits. Halogenated furanones (fimbrolides) from the marine red alga, Delisea pulchra have been shown to interfere with the key signaling pathway present in Gram-negative bacteria by competitively displacing the cognate signaling molecule from the transcription protein. This project focused on the design and synthesis of 1,5-dihydropyrrol-2-ones, a new class of fimbrolide derivatives capable of displaying strong antagonistic properties of the fimbrolides. Primary synthetic methodologies examined include the halolactamization of allenamides and the direct lactone-lactam transformation. No doubt, both methodologies yielded the lactam ring, the former failed to introduce the crucial C-5 bromomethylene group essential for bioactivity. A facile high yielding two-step lactone-lactam transformation method was developed and using this method, a wide range of substituted 5-bromomethyl- and 5-dibromomethylene-1,5-dihydropyrrol-2-ones were synthesized. Furthermore, a new class of tricyclic crown-ether type compounds with no literature precedent were discovered. To vary the diversity of the compounds, a related class of compounds, 5,6-dihydroindol-2-ones, were examined. A general versatile method for the synthesis of 7-substituted 5,6-dihydroindol-2-ones was developed. The synthetic strategy proceeds via the established Suzuki-Miyaura cross-coupling reaction of halogenated dihydroindol-2-ones with arylboronic acids/esters. The Suzuki methodology was found to be reliable in furnishing a wide range of 7-substituted products in high yields. A preliminary molecular modeling approach was used to assist in the design of new anti-microbials via the ligand-docking analyses of the TraR and LasR protein. A positive correlation was observed between the docking scores and biological activity and the methodology was further developed into an initial screening tool to filter potential active and non-active compounds. The newly synthesized compounds were analysed for their efficacy in reducing the expression of the Green Fluorescent Protein (GFP) in the presence of natural AHL signaling molecules in an AHL-monitor strain, indicative of the inhibition of bacterial phenotype expression. The dihydropyrrol-2-one class of compounds showed significant biological activity and this highlighted their potential for further development.

Thesis (Ph. D. in Biochemistry)--Vanderbilt University, Dec. 2005. / Title from title screen. Includes bibliographical references.