Trehalose amide glycolipids as Mincle ligands: Towards new vaccine adjuvants

<p>The development of new vaccines to respond to infectious diseases requires new vaccine adjuvants, which improve vaccine efficacy and shape the immune response. Trehalose glycolipids, consisting of α,α'-trehalose esterified at the 6- and 6'- positions with lipids, exhibit adjuvant activity by binding and activating Macrophage inducible C-type lectin (Mincle). However, the adjuvant activity of trehalose glycolipids could potentially be improved by substituting the ester linkages for more physiologically stable amide bonds. This thesis presents a short protecting group free route to trehalose amide glycolipids, thus allowing for the synthesis of the straight chain glycolipid amides 1a-e in four steps and in excellent (53-61%) overall yields (Figure 1). Amide glycolipids 1a-e were demonstrated to be Mincle agonists with comparable activity to their ester counterparts, as determined using a green fluorescent protein (GFP) reporter cell line assay. A second generation of trehalose amide glycolipids, the lipidated brartemicin amide analogues 2a-c, were subsequently synthesised (Figure 1). This report is the first example of trehalose amide glycolipids acting as Mincle agonists, and further studies into the potential of the amides as vaccine adjuvants will be undertaken in due course.</p>

Trehalose amide glycolipids as Mincle ligands: Towards new vaccine adjuvants

<p>The development of new vaccines to respond to infectious diseases requires new vaccine adjuvants, which improve vaccine efficacy and shape the immune response. Trehalose glycolipids, consisting of α,α'-trehalose esterified at the 6- and 6'- positions with lipids, exhibit adjuvant activity by binding and activating Macrophage inducible C-type lectin (Mincle). However, the adjuvant activity of trehalose glycolipids could potentially be improved by substituting the ester linkages for more physiologically stable amide bonds. This thesis presents a short protecting group free route to trehalose amide glycolipids, thus allowing for the synthesis of the straight chain glycolipid amides 1a-e in four steps and in excellent (53-61%) overall yields (Figure 1). Amide glycolipids 1a-e were demonstrated to be Mincle agonists with comparable activity to their ester counterparts, as determined using a green fluorescent protein (GFP) reporter cell line assay. A second generation of trehalose amide glycolipids, the lipidated brartemicin amide analogues 2a-c, were subsequently synthesised (Figure 1). This report is the first example of trehalose amide glycolipids acting as Mincle agonists, and further studies into the potential of the amides as vaccine adjuvants will be undertaken in due course.</p>

The Microstructure and Rheology of Complex Fluids Containing Na-caseinate

<p>Emulsions are widely utilised in commercial environments, such as in the food and cosmetic industries. In their simplest form, emulsions are a system consisting of two immiscible liquids in the presence of emulsifiers. To form an emulsion, an input of energy is required. In this thesis, Na-caseinate was used as the emulsifier and three systems were studied: soybean oil/Na-caseinate/water, palm oil/Na-caseinate/water and tetradecane/Nacaseinate/ water. Four main techniques were used to characterise the stabilised emulsions: laser diffraction particle sizing, PGSTE-NMR, rheology and cryo-SEM. Emulsion systems are extremely complex making control and predictability over their phase behaviour practically difficult. This is because the required overall characteristics of these colloids are strongly dependent on both the energy of formulation and the choice of an appropriate combination of emulsifier, dispersed phase and continuous phase. A full understanding of the microstructure, stability and physicochemical properties of caseinatestabilised emulsions has as yet not been achieved. For example, how does caseinate selfassembly control emulsion stability? How do concentrated caseinate-based emulsions differ from dilute ones and how do the different oils (food grade oils vs. straight chain hydrocarbon) affect the formation of emulsions? The aim of this PhD programme was to obtain data to allow a better fundamental understanding of the underlying parameters defining emulsion behaviour to be obtained ...</p>

The Microstructure and Rheology of Complex Fluids Containing Na-caseinate

<p>Emulsions are widely utilised in commercial environments, such as in the food and cosmetic industries. In their simplest form, emulsions are a system consisting of two immiscible liquids in the presence of emulsifiers. To form an emulsion, an input of energy is required. In this thesis, Na-caseinate was used as the emulsifier and three systems were studied: soybean oil/Na-caseinate/water, palm oil/Na-caseinate/water and tetradecane/Nacaseinate/ water. Four main techniques were used to characterise the stabilised emulsions: laser diffraction particle sizing, PGSTE-NMR, rheology and cryo-SEM. Emulsion systems are extremely complex making control and predictability over their phase behaviour practically difficult. This is because the required overall characteristics of these colloids are strongly dependent on both the energy of formulation and the choice of an appropriate combination of emulsifier, dispersed phase and continuous phase. A full understanding of the microstructure, stability and physicochemical properties of caseinatestabilised emulsions has as yet not been achieved. For example, how does caseinate selfassembly control emulsion stability? How do concentrated caseinate-based emulsions differ from dilute ones and how do the different oils (food grade oils vs. straight chain hydrocarbon) affect the formation of emulsions? The aim of this PhD programme was to obtain data to allow a better fundamental understanding of the underlying parameters defining emulsion behaviour to be obtained ...</p>

Courtship behavior and identification of a sex pheromone in Ibalia leucospoides (Hymenoptera: Ibaliidae), a larval parasitoid of Sirex noctilio (Hymenoptera: Siricidae)

Background Ibalia leucospoides (Hymenoptera: Ibaliidae) is a larval parasitoid that has been widely introduced as a biological control agent for the invasive woodwasp,Sirex noctilio (Hymenoptera: Siricidae) in the Southern Hemisphere. In this study, the courtship behavior and identificaion of sex pheromones are described for I. leucospoides under laboratory conditions. Methods For courtship behavior, both sexes were observed in a wire mesh observation cylinder (75 cm length ×10 cm diameter) for 15 minutes. The female body washes were analyzed using Gas Chromatography- Electroantennographic Detection (GC-EAD). Then the EAD-active compounds were tentatively identified using GC-Mass Spectrometry (GC-MS) and examined in olfactometer assays. Results The courtship behavior included rhythmic lateral movements, mounting, head-nodding cycles in males, and wing-fanning in females. GC-EAD analysis of female body washes with male antennae revealed seven compounds which elicited antennal responses, four of which are straight-chain alkanes (C23, C25, C26, and C27). The identities of these alkanes were confirmed by matching the retention times, mass spectra, and male antennal activity to those of commercially obtained chemicals. In olfactometer assays, a blend of the four straight-chain alkanes was attractive to I. leucospoides males, and there was no response to blends that lacked any of these four compounds. Female body wash was no more attractive than the four-component blend. The ratios of EAD-active components differ between hydrocarbon profiles from males and females. Conclusion This study is the first investigation of cuticular hydrocarbons in the family Ibaliidae. It provides evidence that the ubiquitous alkanes (C23, C25, C26, and C27) in sex-specific ratios attract I. leucospoides males.

Selectivity in the Formation of Straight-Chain Versus Cyclised products on Knoevenagel Condensation between Thiobarbituric acid and Naphthaldehydes

The prevalence of Clostridium difficile (CD) infection has grown rapidly due to resistance and the emergence of new, highly virulent strains of the organism that have become less sensitive to many antibiotics. Vancomycin and metronidazole are front-line treatments of CD infection that still show good efficacy, but their effectiveness has declined for the treatment of recurrent infection and less sensitive strains of CD. More recently, the macrolide antibiotic fidaxomicin been introduced in the treatment of CD infection. Its high cost and limited usefulness against recurrent infection has prompted the search for new, narrow spectrum agents. We identified the CD dihydroorotate dehydrogenase (DHODase) as a potential enzyme target for the design of Knoevenagel products formed from reaction of 2-thiobarbituric acid and naphthaldehyde substrates. The presence of a hydroxyl substituent at position C2 in the naphthaldehyde ring offers the possibility to form the Knoevenagel product and to cyclize to give the tetracyclic, oxadeazaflavine with benzo-homologation. In this work, the selectivity for straight-chain formation over competing cyclisation on Knoevenagel condensation between thiobarbituric acid and naphthaldehyde substrates was examined. The outcomes of uncatalyzed condensations in refluxing ethanol were investigated by various methods including high field 1H and 13C NMR. Unsubstituted naphthaldehyde and its 2-methoxyl derivative favored straight-chain product formation whereas use of 2-hydroxynaphthaldehyde favored cyclisation and concomitant Michael addition of a second molecule of the corresponding acid to the newly formed exocyclic C=C bond. The pattern of reactivity was mirrored in the benzaldehyde series where the presence of the 2-hydroxyl function led to cyclized products with concomitant formation of the Michael adducts. The Knoevenagel products and the benzo-homologated oxadeazaflavine derivatives are candidates for evaluation as potential growth inhibitors of CD.