The prevalence of both Type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) is increasing worldwide, and the trends are unfortunately expected to continue. AD has recently been tied with mitochondrial dysfunction and insulin resistance, creating a mechanistic tie between AD and T2DM. Unfortunately, insulin resistance is often increased with aging and therefore, all individuals are at risk of brain mitochondrial dysfunction. Without proper mitochondrial function, the brain will degenerate, causing impaired cognitive function and reduced quality of life. The purpose of this study is two-fold: first, to understand the role of ceramides in insulin-induced brain mitochondrial dysfunction, and; second, to understand how ketones can restore brain mitochondrial function in aged brains. To evaluate the role of insulin resistance and ceramides in brain mitochondrial function, we induced hyperinsulinemia in ApoE4 mice. In addition to insulin, one group received myriocin injections to inhibit ceramide biosynthesis. We observed significant increases in brain ceramides in the insulin-treated group, which correlated with disrupted brain mitochondrial function. However, the group receiving myriocin alone, and, importantly, myriocin with insulin, had normal lipid profiles and normal mitochondrial bioenergetics. Altogether, these findings support the hypothesis of the key role of ceramides in insulin resistance-induced mitochondrial dysfunction within the brain. Next, young adult (5 months old) and old (28 months old) rats were assigned to either standard chow diets or very-low-carbohydrate, high-fat, ketogenic diets for 4 weeks. Following the treatment period, we analyzed brain mitochondrial function and oxidative stress. We found that the old rats fed the ketogenic diet had improved mitochondrial function in comparison to the old rats consuming standard rodent chow. In addition, the old rats fed a standard diet had significantly higher levels of oxidative stress than the aged rats on the very-low-carbohydrate, high-fat diet. These findings revealed that ketones can protect brain mitochondrial function in aging. Collectively, these results suggest that insulin resistance has a role in the development of brain mitochondrial dysfunction due to ceramide accumulation, while ketones can help mitigate some of the negative consequences of aging, perhaps some due to insulin resistance, on brain mitochondrial function.

No description available.

Reaction of phenyl vinyl sulfoxide with the lithium enolates of simple ketones of varying ring size (cyclopentanone, cycloheptanone and cyclooctanone) under controlled cyclisation conditions followed by subsequent oxidation resulted in the formation of the bicyclo[n.2.0]alkan-1-ols 253-255, 262, 263, 265, 268 and 269 in conjunction with alkylated species 256, 257, 264, 266 and 267. The ratio of bicyclo[n.2.0]alkan-1-ols to alkylated ketone formation observed was dependent on a number of factors including the variation of enolate reactivity between the different ring sizes, conversion of phenyl vinyl sulfoxide, time, temperature and concentration of reaction and the stability and steric strain observed in the final bicyclo[n.2.0]alkan-1-ol product. X-ray crystal structures of 253, 262 and 265 were obtained and a structural study showed that as the overall steric strain in the bicyclo[n.2.0]alkan-1-ol product is decreased there is a corresponding increase in product distribution in favour of bicyclo[n.2.0]alkan-1-ol formation in conjunction with increased yields. Selected substituted and functionalised ketones (2-methylcyclopentanone, 2,6-dimethylcyclohexanone, 2-methylcyclohexanone and 1,4-cyclohexanedione mono-ethylene ketal) also reacted in the cyclisation reaction to give bicyclo[n.2.0]alkan-1-ols 270, 271, 277, 278, 281, 282, 285 and 286 in conjunction with alkylated products 272, 279, 280, 283, 284 and 287. Incorporation of substitution at the bridgehead and C2 position had a role in the preference of the major stereochemical isomer observed for a bicyclo[n.2.0]alkan-1-ol (n = 3, 4). A structural comparison of the X-ray crystal structures of 278, 281 and 286 indicated that the pseudo chair conformation of the six-membered ring influenced ring torsion and bond angles in the bicyclo[4.2.0]octanol ring system. Two model studies were selected to illustrate the potential application of the cyclisation process as methodology towards natural product synthesis or complex ring systems. No bicyclo[n.2.0]alkan-1-ol formation was evident in an intramolecular example using the starting ketone 291 in which the electrophile is tethered to the ketone. 2,6-Dimethyl-2-cyclohexen-1-one 301 considered as a model study towards the synthesis of the antibiotic mellolide, upon reaction with phenyl vinyl sulfoxide and oxidation displayed poor reactivity. The novel bicyclo[2.2.2]octanones 303, 304 and 305 were formed in very low yields. The lack of reactivity of the ketones 2,6-dimethyl-2-cyclohexen-1-one, 1,2-cyclohexanedione and 1,4-cyclohexanedione towards bicyclo[n.2.0]alkan-1-ol formation suggested that conjugation in the enolate prior to reaction with phenyl vinyl sulfoxide was not favourable. The non-reactivity of these ketones and the hindered ketone camphor indicated the potential limitations to the cyclisation methodology. However, conversion of the ketal functionality of 286 to a ketone resulted in the formation of the functionalised bicyclo[4.2.0]octanol 288 providing positive indications for further synthetic applications.

Thesis (M.S.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed December 5, 2007) Includes bibliographical references (p. 55-60).

Dietary manipulations and their pharmacological outcomes have been increasingly studied in neurodegenerative diseases. However, a systematic comparison among different methods in validated animal models of Alzheimer's disease is made necessary due to several different approaches applied in recent studies. Moreover, despite the large body of evidence on the effects of calorie restriction (CR) and ketogenic diets (KDs) on amyloid pathology, no consistent data is available on the effects of calorie restriction, ketogenic diet or ketone supplements on tau pathology in transgenic models of AD. Moreover, the ketogenic diet used in our studies was custom made with low carbohydrate content and rich in medium chain triglyceride (MCT) oils, known to be rapidly metabolized in the liver, resulting in sustained peripheral ketosis. Chapter 1 tested the ability of KD to induce significant ketosis in a mouse model of amyloid deposition. We showed that, despite the mild ketosis induced, KD fed APP mice presented subtle behavioral improvement shown as faster learning in the radial arm water maze, making less errors than APP mice kept on a control diet. Additionally, we observed decreased Aβ immunoreactivity in the anterior cortex of KD fed versus control fed APP mice, despite the lack of changes in congophilic deposits. Due to the mild ketosis induced, a modified ketogenic diet was devised with decreased maltodextrin content and showed greater peripheral levels of β-hydroxybutyrate. Chapter 2 investigated the effects of a ketogenic diet in two transgenic mouse models of Alzheimer's pathology. Interestingly, we found that both transgenic lines, regardless of diet, weighed less than nontransgenic mice, despite their elevated food intake. The reduced body weight may, in part, be explained by the increased locomotor activity shown by both transgenic lines in both the open field and y-maze. Moreover, KD fed mice performed significantly better on the rotarod compared to mice on the control diet independent of genotype. We did not observed KD-induced changes in spatial or associative memory in the radial arm water maze or contextual fear conditioning, respectively. Furthermore, immunohistochemical levels of amyloid, tau, astrocytic and microglial markers showed no differences between animals fed KD or the control diet. Chapter 3 studied the effects of calorie restriction on a mouse model of tau deposition. We show here that 35% body weight reduction in Tg4510 mice did not prevent increased locomotor activity in the open field, previously reported in chapter 2. Similarly, CR did not affect motor performance or spatial memory assessed by the rotarod and radial arm water maze, respectively. Interestingly, CR Tg4510 mice showed improved short-term memory tested by the novel object recognition despite spending a minimal percentage of the trial time interacting with the objects presented. However, this improvement was not observed when the test was modified to replace the objects with mice. In this case, we noticed that nontransgenic mice spent most of the trial time interacting with the novel mouse whereas Tg4510 mice spent roughly the same amount of time at any of the areas in the test chamber. Moreover, no changes in histopathological or biochemical levels of tau, astrocytic, microglial or synaptic markers were observed. Chapter 4 sought to investigate alternative approaches to inducing ketosis in the brain by either administering BHB intracerebroventricularly (i.c.v.) or by using the acetoacetate (AcAc) diester as a dietary supplement in mice. We observed that i.c.v administration of BHB in 20 months old APP mice did not affect body weight or food intake. Consistent with the lack of effects on behavioral performance, amyloid and congophilic load were not different between APP mice infused with either saline or BHB. We also found that enteral administration of AcAc diester was well tolerated and induced peripheral ketosis for at least 3 hours. Acute ketosis, however, was not sufficient to attenuate behavioral deficits in old APP mice. Chronic dietary supplementation with AcAc was tested in control tet mice and was shown to effectively induce ketosis in mice fed a diet with normal contents of carbohydrates. Nonetheless, we observed that AcAc-induced ketosis was not significantly greater than levels induced by the ketogenic diet tested in our lab. Considering that KD did not rescue behavioral or histopathological features of either amyloid or tau depositing mouse models, we anticipated that dietary supplementation with AcAc would not likely modify the phenotype of the same mouse models tested previously. Taken together, our findings show that our custom made ketogenic diet was effective in inducing and sustaining ketosis and may play an important role in enhancing motor performance in mice. However, the lack of changes on the cognitive and histopathological phenotype of the models studied suggests that KD may not be a disease modifying therapeutic approach to AD. Moreover, calorie restriction showed inconsistent effects on behavioral and histopathological outcomes of a mouse model of tauopathies. Furthermore, dietary supplementation with acetoacetate diester was successful in inducing peripheral ketosis to the same extend as a ketogenic diet even in the context of normal carbohydrate intake, suggesting that it may be of therapeutic interest for diseases of hypometabolism but not a disease modifying therapy in mouse models of Alzheimer's pathology.

Understanding how metabolites contribute to anaplerosis, antioxidant effects, and hormetic pathways during aging is fundamental to creating supplements and dietary habits that may decrease age-associated disease and decline, thus improving the quality of life in old age. In order to uncover metabolic pathways that delay aging, the effects of large sets of metabolites associated with mitochondrial function on lifespan were investigated. Malate, the tricarboxylic acid (TCA) cycle metabolite, increased lifespan and thermotolerance in C. elegans. Addition of fumarate and succinate also extended lifespan and all three metabolites activated nuclear translocation of the cytoprotective DAF-16/FOXO transcription factor and protected from paraquat-induced oxidative stress. The increased longevity provided by malate addition did not occur in fumarase (fum-1), glyoxylate shunt (gei-7), succinate dehydrogenase flavoprotein (sdha-2), or soluble fumarate reductaseF48E8.3 RNAi knockdown worms. Therefore, to increase lifespan, malate must be first converted to fumarate, then fumarate must be reduced to succinate by soluble fumarate reductase and the mitochondrial electron transport chain complex II. Lifespan extension induced by malate depended upon the longevity regulators DAF-16 and SIR-2.1. Malate supplementation did not extend the lifespan of long-lived eat-2 mutant worms, a model of dietary restriction. Malate and fumarate addition increased oxygen consumption, but decreased ATP levels and mitochondrial membrane potential suggesting a mild uncoupling of oxidative phosphorylation. Each of the twenty amino acids was individually supplemented to C. elegans and the effects on lifespan were determined. All amino acids except phenylalanine were found to extend lifespan at least to a small extent at one or more of the 3 concentrations tested with serine, histidine, and proline showing the largest effects. In most cases, amino acid supplementation did not extend lifespan in eat-2 worms, a model of dietary restriction or in daf-16, sir-2.1, rsks-1 (S6 kinase), or aak-2 (AMPK) longevity pathway mutants or in worms fed RNAi to skn-1, the C. elegans Nrf2 homolog. Serine and tryptophan addition further protected worms from Alzheimer’s amyloid-beta toxicity. Tryptophan and its catabolites nicotinic acid, picolinic acid, and NAD further induced a broad heat shock response. These results indicate that dietary amino acid imbalance and amino acid catabolism affect organismal longevity. The ketone body beta-hydroxybutyrate (βHB) is a histone deacetylase (HDAC) inhibitor and has been shown to be protective in many disease models, but its effects on aging are not well studied. Therefore we determined the effect of βHB supplementation on the lifespan of C. elegans. βHB supplementation extended mean lifespan by approximately 20%. RNAi knockdown of HDACs hda-2 or hda-3 also increased lifespan and further prevented βHB-mediated lifespan extension. βHB-mediated lifespan extension required the DAF-16/FOXO and SKN-1/Nrf longevity pathways, the sirtuin SIR-2.1, and the AMP kinase subunit AAK-2. βHB did not extend lifespan in a genetic model of dietary restriction indicating that βHB is likely functioning through a similar mechanism. βHB addition also upregulated ΒHB dehydrogenase activity and increased oxygen consumption in the worms. RNAi knockdown of F55E10.6, a short chain dehydrogenase and SKN-1 target gene, prevented the increased lifespan and βHB dehydrogenase activity induced by βHB addition, suggesting that F55E10.6 functions as an inducible βHB dehydrogenase. Furthermore, βHB supplementation delayed Alzheimer's amyloid-beta toxicity and decreased Parkinson's alpha-synuclein aggregation. The results indicate that D-βHB extends lifespan through inhibiting HDACs and through the activation of conserved stress response pathways. Aging is a progressive disease caused by the time dependent decline of an organism and is the primary risk factor for many human ailments, including heart disease, cancer, and Alzheimer’s disease. Uncovering metabolic pathways and metabolites that delay the onset of age-related decline was the primary drive of this investigation.

By simply hydrogenating enones in the presence of aldehydes at ambient temperature and pressure, aldol adducts are generated under neutral conditions in the absence of any stoichiometric byproducts. Using cationic rhodium complexes modified by tri(2-furyl)phosphine, highly syn-diastereoselective reductive aldol additions of vinyl ketones are achieved. Finally, using novel monodentate TADDOL-like phosphonite ligands, the first highly diastereo- and enantioselective reductive aldol couplings of vinyl ketones were devised. These studies, along with other works from our laboratory, demonstrate that organometallics arising transiently in the course of catalytic hydrogenation offer byproduct-free alternatives to preformed organometallic reagents employed in classical carbonyl addition processes. Existing methods for enantioselective carbonyl allylation, crotylation and tert-prenylation require stoichiometric generation of pre-metallated nucleophiles, and often employ stoichiometric chiral modifiers. Under the conditions of transfer hydrogenation employing an ortho-cyclometallated iridium C,O-benzoate catalyst, enantioselective carbonyl allylations, crotylations and tert-prenylations are achieved in the absence of stoichiometric metallic reagents or stoichiometric chiral modifiers. Moreover, under transfer hydrogenation conditions, primary alcohols function dually as hydrogen donors and aldehyde precursors, enabling enantioselective carbonyl addition directly from the alcohol oxidation level. / text

Curcumin is one of the major curcuminoids produced by the ginger family Zingiberaceae. These curcuminoids possess pharmacological properties that include anticancer activities. We have evaluated some synthetic curcumin analogues that have shown potential as anticancer drugs. These antineoplastic agents bearing the 1,5-diaryl-3-oxo-1,4-pentadienyl pharmacophore are electrophiles which are designed to preferentially react with sulfhydryl groups present in proteins as opposed to amino and hydroxyl groups present in DNA. In previous pilot studies, three derivatives examined in this thesis showed inhibition towards human cancer cell lines such as Molt 4/C8 and CEM T-lymphocytes. In this thesis work, I determined the cytotoxicity of these derivatives and curcumin towards human colon cancer (HCT-116) cells and also normal colon epithelial (CRL-1790) cells, and examined the possible mechanism(s) involved. I hypothesized that they act via induction of reactive oxygen species (ROS) which elicit a transient surge of mitochondrial ROS generation and a phenomenon known as ROS-induced ROS release (RIRR), along with the mitochondrial permeability transition (MPT) and mitochondrion –dependent apoptosis. I asked whether these agents react with some of the key protein thiols in the mitochondria whose oxidation/alkylation results in mitochondrion - dependent apoptosis. NC-2109 and NC-2346 were found to be potent cytotoxic agents based on their GI50 values of 0.87 ± 0.38 μM and 0.90 ± 0.22 μM, respectively, and were more potent than the anticancer drug 5-fluorouracil (GI50 = 5.47 ± 0.55 μM) and curcumin (GI50 = 3.50 ± 0.36 μM). However NC-2109 was found to have a better selectivity towards cancer cells over normal cells (a selectivity index of 18.81 versus 5-FU, curcumin and NC-2346 which had selectivity indices of 1.87, 16.75 and 4.61, respectively). In the investigations of the mechanisms involved, both curcumin and curcumin analogues were able to induce mitochondrial ROS production. Moreover, curcumin and its synthetic counterparts showed a biphasic ROS profile which is most characteristic of RIRR. Treatment with these agents also led to the disruption of the mitochondrial membrane potential, suggesting oxidation of protein thiols and the opening of the mitochondrial permeability transition pore which is an important step to initiate mitochondria-directed apoptosis. This possibility was confirmed based on GSSG/GSH ratios, since curcumin, NC-2346 and NC-2109 all produced a higher GSSG/GSH ratio than the controls. In addition to their ability to depolarize the mitochondrial membrane in HCT-116 cells, that these molecules acted via the mitochondrial pathway were further authenticated based on their ability to induce mitochondrial swelling in rat liver mitochondria. In another part of this thesis I evaluated the involvement of the critical thiol protein adenine nucleotide translocase (ANT), a bifunctional protein that plays a central role in mitochondrial apoptosis. ANT has four different isoforms; ANT1 and ANT3 are proapoptotic, while ANT2 and ANT4 are antiapoptotic and are overexpressed in cancer states. A combination approach using ANT2 siRNA however did not conclusively show whether these agents acted synergistically with ANT2 knockdown to potentiate mitochondria-mediated cell death. An alternative combination approach was the use of carboxyatractyloside (CAT) which binds to and retains ANT in its ‘c’ conformation, exposing thiols and potentially driving a cell towards programmed cell death. The presence of CAT enhanced the ability of curcumin and its synthetic analogs to collapse the mitochondrial membrane potential, an important step in mitochondrial-mediated apoptosis. In conclusion, curcumin and the curcumin analogue NC-2109 were found to be cytotoxic in vitro, towards HCT-116 cells and also showed good selectivity. In addition, these two molecules were found to be ROS inducers, and coincidentally oxidized cellular thiols and caused depolarization of the mitochondrial membrane potential. The results support a mechanism of mitochondrial-mediated cell death upon MPT pore formation (mitochondrial swelling), perhaps involving ANT2. This conclusion was further supported by the potentiation of cell death in the presence of the ANT2 inhibitor, CAT.

Although carbon dioxide as a greenhouse gas is a serious environmental concern, it remains a valuable C1 source if viable methods are available for its conversion into useful products. Herein, we present recent progress in the synthesis of aliphatic, aromatic, cyclic, and bicyclic beta-ketocarboxylic acids and the promising results from subsequent asymmetric hydrogenation to give beta-hydroxycarboxylic acids. For the synthesis of the beta-ketocarboxylic acids, we investigated the effects of temperature, reaction time, and amount of 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU), which is a promoter for carbon-carbon bond formation with CO2. The highest-yielding conditions for this DBU-promoted carboxylation reaction were used to carboxylate a number of aliphatic and aromatic substrates. In order to determine whether the hydrogenation reaction will effectively compete with the in situ decarboxylation of the beta-ketocarboxylic acids, 1H NMR spectroscopy was used to monitor the rate of decarboxylation. The solvent, electronic, and steric effect on the rate of decarboxylation was investigated by testing a variety of beta-ketocarboxylic acids. Using œRuCl2{(S)-BINAP} catalyst precursor, we determined the effect that solvent, H2 pressure, base, and substrate substitution had on the enantioselectivity of the asymmetric hydrogenation. CH2Cl2 and MeOH were determined to be the best solvents because of the high hydrogenation selectivity, high enantioselectivity, and decreased reaction times. These standard conditions were used to hydrogenate the variety of aliphatic and aromatic beta-ketocarboxylic acids previously synthesized. Additional experiments, including deuterium labelling, were performed in an attempt to elucidate the hydrogenation mechanism and the actively hydrogenated tautomer. These results lead us to believe that different reaction pathways occur in protic versus aprotic solvents. The results discussed herein represent the first in depth investigation of transition metal catalyzed hydrogenation of beta-ketocarboxylic acids. These results are very encouraging because enantioselectivities greater than 99 % were achieved for multiple beta-keto acids. This synthesis is industrially advantageous due to the limited number of reactants required, their low-cost, and the potential for recycling unused materials. / Thesis (Master, Chemistry) -- Queen's University, 2008-08-26 10:17:34.703

No description available.