A major problem associated with cellular cryopreservation is the recovery of cellular viability upon thawing. Current cryopreservation techniques use additives such as DMSO, sucrose and fetal bovine serum. However, each have their own respective cytotoxic issues. A significant factor in cryotoxicity is the formation of large ice crystals which can damage cellular components and cause dehydration. This has significant impacts for applications such as food preservation, scientific research, and tissue preservation. To this end, our laboratory is interested in synthesizing biologically-relevant compounds that can act as cryoprotectants by preventing the formation of large ice crystals in sub-zero temperatures. Our lab has previously synthesized structural analogues of native antifreeze glycoproteins (AFGPs, found in the blood of Antarctic cod), that possess the unique ability to inhibit ice-recrystallization. However, the mechanism by which they inhibit ice recrystallization is unclear. This thesis focuses on efforts made to understand this mechanism, and synthesize molecules that are more potent in ice recrystallization inhibition (IRI) activity compared to previously synthesized analogues. By assessing the IRI activity of various mono- and disaccharides, we have shown that the density of water molecules that surround a carbohydrate (Hydration Index) is directly proportional to the ability of sugars to inhibit ice crystal growth. In an effort to design functional AFGP analogues, various C-linked analogues were synthesized that contained different spacer lengths between the carbohydrate and the peptide backbone. Analyses of the solution conformations of these analogues showed that IRI-active AFGP analogues contain a distinct conformation in which the carbohydrate is oriented to form a hydrophobic pocket with the side chain. We hypothesize that this change in glycoconjugate hydration is responsible for disturbing its surrounding waters, thereby preventing water from adding to the ice lattice required for ice growth. Finally, SAR studies showed that threonine-containing AFGP and antifreeze proteins are more potent in antifreeze activity than serine-containing analogues. As the most potent AFGP analogue previously synthesized by our lab contains a C-linked-α-galactosyl -serine residue, we hypothesized that the analogous glycopeptide containing a C-α-galactosyl-threonine residue will be more potent in antifreeze activity. The final section describes efforts to synthesize a C-linked α-galactosyl-threonine glycoconjugate.

The efficiency of an intermolecular synthetic transformation can be improved by temporarily linking reaction components together. The addition of a tether leads to enhanced regio- and stereocontrol by restraining the mobility of the reacting partners, effectively transforming an intermolecular reaction into its intramolecular counterpart. Silicon tethers are associated with an expanding range of applications, including hydrosilylations, cycloadditions and radical reactions. This project has continued work pioneered by the Robertson group into silicon tethered Type I ene cyclisations, extending the methodology to incorporate O-linked ene precursors with the intention of applying this chemistry to the stereoselective synthesis of non-natural carbohydrates. This investigation encompassed advances in the area made concurrently within the Robertson group and extended the scope of the ene protocol by successfully incorporating latent functionality into the R-group side chain. In addition, a new route to the O-linked ene precursors was established employing silylcyanohydrin chemistry. In general, the ene reactions proceeded stereoselectively to generate the expected oxasilacyclohexanols, which could be cleaved oxidatively to afford 1,2,4-triols. The formation of the major diastereomer was consistent with ene cyclisation proceeding through a trans-decalin type transition state (e.g. leading to compound 1). During our attempts to effect ene cyclisation in the O-linked prenyl systems we observed an unexpected side reaction, resulting from intramolecular allylic transfer. Further studies revealed that this novel process could be initiated thermally to generate 1,2-homoallylic diols with excellent levels of stereoselectivity. Tethered E- and Z-crotylsilanes were found to be equally receptive to this process. Although attempts to apply the silicon tethered allyl transfer chemistry to aldimines and glycosides failed, an extension of the methodology to incorporate cyclohexadienylsilanes was successful and provided interesting synthetic intermediates for elaboration to carbasugars.

This thesis describes approaches to the transformation of simple carbohydrates into a polyhydroxylated pyrrolidine and the formation of its glucosides. Chapter one describes the synthesis of the naturally occurring pyrrolidine 2,5-dideoxy-2,5-imino-D-mannitol. Synthesised from di-O-isopropylidene-D-glucose, the key steps are the introduction of nitrogen at C-5 with retention of configuration. Then cyclisation of the nitrogen onto the C-2 position with inversion to form the pyrrolidine ring. Reduction of the aldehyde furnished the polyhydroxylated heterocycle in 3.4% yield over 16 steps. The synthetic compound matched the naturally occurring compound in all respects. Chapter two contains a review of commonly used glycosylation methods. It also describes the glycosylation of di-O-isopropylidene-α-D-glucose as a model system comparing the Koenig-Knorr method to the trichloroacetimidate method using several reaction conditions. Glycosylation of 2,5-dideoxy-2,5-imino-D-mannitol was carried out using the trichloroacetimidate method to synthese all four glucosides. Boron trifluoride etherate and trimethylsilyl trifluoromethanesulphonate were used as catalysts in dichloromethane, diethyl ether and acetonitrile under strictly anhydrous conditions. All four glucosides were prepared 1-O-(αβ-D-glucopyranosyl)-2,5-dideoxy-2,5-imino-D-mannitol and 3-O-(αβ-D-glucopyranosyl)-2,5-dideoxy-2,5-imino-D-mannitol. Biological screening carried out against a wide range of glycosidases and glycosyl transferases indicated that the glucosides showed little inhibition in comparison to 2,5-dideoxy-2,5-imino-D-mannitol. Chapter three describes the isolation and identification of 1-O-(β-D-glucopyranosyl)- 2,5-dideoxy-2,5-imino-D-mannitol from Nephthytis poisonii N.E.Br. a member of the Araceae family found in tropical Africa. Identification was made by comparison with the previously synthesised glucosides of 2,5-dideoxy-2,5-imino-Dmannitol. Investigations of Hyacinthoides non-scriptus (L.) chouard ex Rothm are also discussed. Chapter four describes the synthesis of a diazidolactone that could be used to form a 1,5 disubstituted tetrazole. This would have a second nitrogen functionality in the molecule allowing the possibility of the inclusion of the tetrazole into a peptide sequence. The synthesis was carried out from L-gulono-1,4-lactone. An azido group was introduced selectively at C-2, this unexpectedly occurred with retention of configuration. A second azide was then introduced at C-5, this occurring with the more commonly observed inversion of configuration to afford the 2,5-diazido-2,5-dideoxy-D-manno-1,4-lactone.

The purpose of this thesis was to study the effects of a pre-exercise carbohydrate meal on metabolism, endurance capacity and performance during prolonged running when carbohydrate was, or was not consumed during exercise. The first study (Chapter 4) examined the effects on endurance running capacity of ingesting a carbohydrate-electrolyte solution during treadmill exercise to fatigue at 70% V02 max after subjects (10 males) had undergone an overnight fast (P+C), or when fed with a 2.5 g. kg-1 BW carbohydrate meal 3 hours before exercise (M+C). Exercise time to exhaustion was longer in the M+C (147.4 ± 9.6 min) and P+C (125.1 ± 7.0 min) trials compared with the control condition (P+P: 115.1 ± 17.6 min) (p< 0.01 and p< 0.05 respectively). Also, exercise time was longer in the M+C compared with the P+C trial (p< 0.01). The improvement in endurance capacity in the M+C trial occurred despite a higher carbohydrate oxidation rate during the first hour of exercise. The second study (Chapter 5) examined whether a pre-exercise carbohydrate meal (M+W) can improve endurance capacity, and further examined if the combination of a pre-exercise meal together with the ingestion of a carbohydrate-electrolyte solution during exercise (M+C) would be superior to the carbohydrate meal (M+W) alone. Ten males volunteered in this study. Although the consumption of the meal increased carbohydrate oxidation during the first hour of exercise, exercise time to fatigue at 70% V02 max was longer in the M+C (125.1 + 5.3 min) and M+W (111.9 + 5.6 min) trials compared with the control trial (P+W : 102.9 ± 7.9 min) (p< 0.01 and p< 0.05 respectively). Also, exercise time was longer (p< 0.05) in the M+C compared with the M+W trial. The third study (Chapter 6) investigated whether the high carbohydrate meal can influence muscle glycogen levels. Eight male subjects participated in the study. Three hours after the ingestion of the 2.5 g. kg-1 BW carbohydrate meal, muscle glycogen concentration was 10.6% higher (p< 0.05) in the vastus lateralis muscle (347.3 + 31.3 mmol. kg dw-1) compared with the muscle glycogen concentration before feeding (314 ± 33.9 mmol. kg dw-1). The fourth study (Chapter 7) examined the influence of ingesting a carbohydrate-electrolyte drink (M+C) on the muscle glycogen utilisation during 60 min running at 70% V02 max in subjects (8 males) who had consumed a carbohydrate meal 3 hours before exercise (M+W). Muscle glycogen concentrations were not different before (M+C : 321.9 ± 27.2 vs M+W : 338.8 ± 32.8 mmol. kg dw-1), as well as after exercise (M+C : 225.8 ± 26.7 vs M+W: 261 + 40.5 mmol. kg dw-1) between the two experimental trials. Neither was there any difference in the rate of muscle glycogen utilisation (M+C : 96.1 ± 22.1 vs M+W: 77.9 ± 11.7 mmol. kg dwl. h-1). The aim of the last study (Chapter 8) was to investigate whether, after an overnight fast, the ingestion of a carbohydrate-electrolyte solution during a 30 km self-paced treadmill run (C) would be as effective as the consumption of a carbohydrate meal (M) (2.0 g. kg-1 BW carbohydrate) 4 hours before exercise. Ten males volunteered for this study. The overall performance times in the M and C trials were identical (M: 121.8 ± 3.6 min vs C: 121.7 ± 4.1 min). No differences were found between the two trials in running speeds over each successive 5 km, or even when running speed was analysed every kilometre. Also, no reduction in the self-selected speeds of subjects was observed towards the end of the 30 km run in both conditions. The ingestion of a carbohydrate meal, providing 2.5 g. kg-1 BW carbohydrate, 3 hours before exercise increases muscle glycogen concentration and improves endurance running capacity, despite an elevated carbohydrate oxidation rate during the first hour of exercise. It seems that the amount of carbohydrate given before exercise compensates for the greater carbohydrate used. Furthermore, the combination of both a pre-exercise carbohydrate meal and a carbohydrate-electrolyte solution ingested during exercise further improves endurance capacity.

Carbohydrate and protein interactions are often essential in viral and bacterial infection, the immune response, cell differentiation and development, and the progression of tumor cell metastasis. Therefore, an understanding of carbohydrate–protein interactions at the molecular level would lead to a better insight into the biological process of living systems and assist in the development of therapeutic and diagnostic strategies. Our goal was to synthesize different mannose derivatives, immobilize them on nano-patterned surfaces and carry out binding studies with mannose-binding lectins in order to characterize carbohydrate–protein interactions. Different derivatives of D-mannose (monosaccharide, (1→2)-linked disaccharide, (1→3)-linked disaccharide, and (1→2, 1→3)-linked trisaccharide) with tethered –SH groups were synthesized. Alkyne-terminated D-mannose derivatives were synthesized to be immobilized via click chemistry on azide-functionalized glass slides. These molecules were constructed by glycosylation of appropriately protected glycosyl donors and acceptors, followed by free-radical addition to introduce the thiol terminals onto the aglycons. Subsequent deprotection afforded the corresponding free-OH saccharides. Standard robotic microarray printing technology was used to couple these thiol-terminated aglycons to epoxide-functionalized glass slides. Using a fluorescence scanner, binding between carbohydrates and Con A were quantified and processed to obtain dissociation constants (KD). The (1→2)-linked disaccharide 18 showed highest binding with Con A with dissociation constant of 58 nM [nano molar]. The (1→3)-linked disaccharide 24 had a dissociation constant of 68 nM [nano molar] with Con A. The differences in binding constants seem to be greater at higher concentrations above 400 μM [micro molar]. The monosaccharide 5 had an average surface dissociation constant of 76 nM [nano molar] and 91 nM [nano molar] for the trisaccharide 29. In general, the disaccharides 18 and 24 showed enhanced binding interaction with Con A than the monosaccharide 5 and trisaccharide 29.

Potassium is one of the essential plant nutrient elements. It is used by plants in the synthesis and distribution of carbohydrates and in the formation of proteins and oils. Potassium also seems to exert many of tis effects by influencing enzymatic activity in cells. The fact that potassium is being removed from Utah soils at a rather rapid rate raises the question as to whether any apprecialbe proportion of these soils are now deficient or are approaching a deficiency in this element. Some farmers, fertilizer salesmen, and others, have expressed a belief that many soils of the state are now at a deficiency level. Workers in the Utah Agricultural Experiment Station report that field experiments indicate no crop responses to potassium fertilizers and express that opnion that soil deficiencies in potassium are not common here. The purpose of this investigation is to evaluate present information regarding the need for potassium fertilizers in Utah soils and to study some of the soil types in regard to their contents of available potassium and probable need for potash fertilizers in the near future.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2005. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2004. / Härtill 5 uppsatser.

Diss. (sammanfattning) Uppsala : Univ., 2001. / Härtill 4 uppsatser.