Peroxisomal regulation of redox homeostasis and adipocyte metabolism

Peroxisomes are ubiquitous cellular organelles required for specific pathways of fatty acid oxidation and lipid synthesis, and until recently their functions in adipocytes have not been well appreciated. Importantly, peroxisomes host many oxygen-consumption reactions and play a major role in generation and detoxification of reactive oxygen species (ROS) and reactive nitrogen species (RNS), influencing whole cell redox status. Here, we review recent progress in peroxisomal functions in lipid metabolism as related to ROS/RNS metabolism and discuss the roles of peroxisomal redox homeostasis in adipogenesis and adipocyte metabolism. We provide a framework for understanding redox regulation of peroxisomal functions in adipocytes together with testable hypotheses for developing therapies for obesity and the related metabolic diseases

Protein modification and maintenance systems as biomarkers of ageing

Changes in the abundance and post-translational modification of proteins and accumulation of some covalently modified proteins have been proposed to represent hallmarks of biological ageing. Within the frame of the Mark-Age project, the workpackage dedicated to "markers based on proteins and their modifications" has been firstly focused on enzymatic and non-enzymatic post-translational modifications of serum proteins by carbohydrates. The second focus of the workpackage has been directed towards protein maintenance systems that are involved either in protein quality control (ApoJ/Clusterin) or in the removal of oxidatively damaged proteins through degradation and repair (proteasome and methionine sulfoxide reductase systems). This review describes the most relevant features of these protein modifications and maintenance systems, their fate during ageing and/or their implication in ageing and longevity

Interspecific hybrids of potato : determination of glycoalkaloid aglycones and influence of bacterial infection

v2004okKJB. Yksikön huom.: KJBDiss. : Helsingin yliopisto, 200

Chemical Composition and Biological Activities of Mentha Species

The genus Mentha L. (Lamiaceae) is distributed all over the world and can be found in many environments. Mentha species, one of the world’s oldest and most popular herbs, are widely used in cooking, in cosmetics, and as alternative or complementary therapy, mainly for the treatment of gastrointestinal disorders like flatulence, indigestion, nausea, vomiting, anorexia, and ulcerative colitis. Furthermore, it is well documented that the essential oil and extracts of Mentha species possess antimicrobial, fungicidal, antiviral, insecticidal, and antioxidant properties. The economic importance of mints is also evident; mint oil and its constituents and derivatives are used as flavoring agents throughout the world in food, pharmaceutical, herbal, perfumery, and flavoring industry. To provide a scientific basis for their traditional uses, several studies have been conducted to determine the chemical composition of mints and assess their biological activities. This chapter describes the therapeutic effects and uses of Mentha species and their constituents, particularly essential oils and phenolic compounds; some additional biological activities will also be considered

The Formyl Peptide Receptor 2 Regulates Microglial Phenotype Through Immunometabolism: Implications for Alzheimer’s Disease

Microglia are key players in the pathology of Alzheimer’s disease (AD), driving chronic inflammation, oxidative stress, and the altered metabolism seen in the brains of patients. With clinical trials continuing to fail, new approaches towards drug development are critical. Strategies to reduce microglial activation may therefore be a viable therapeutic approach to tackling AD. Formyl peptide receptor 2 (Fpr2), which drives peripheral inflammatory resolution, is expressed in microglia. However, its functional role in neuroinflammation is unclear. This thesis provides evidence to support the peripheral findings of Fpr2 stimulation, wherein it may also hold promise for exploitation as a therapeutic for neurodegenerative disorders, including AD. We also highlight novel findings surrounding the modulation of both oxidative stress and microglial metabolism associated with Fpr2 activation. Under inflammatory conditions, we report that selective agonists for Fpr2 modulate the microglial inflammatory response, actively shifting from a pro-inflammatory to a pro-resolving phenotype, emphasised by the reduction of pro-inflammatory cytokines and concomitant increases in both pro-resolving cytokines and phagocytosis. Metabolic shifting away from glycolysis was also observed for pro-resolving microglia. Moreover, we describe for the first time that Fpr2 completely reverses reactive oxygen species (ROS) production from the mitochondria and NADPH oxidase enzymes following an inflammatory stimulus. We also highlight that the toxic oligomeric amyloid (oAβ) facilitates microglial ROS production and subsequent metabolic changes without triggering an inflammatory response. oAβ facilitated NADPH oxidase activation, which in turn resulted in the activation of glucose 6-phosphate dehydrogenase (G6PD), the rate limiting step for the pentose phosphate pathway. This metabolic pathway is responsible for producing NADPH, which in turn NADPH oxidases exploit for further ROS production. These changes resulted in noticeable reductions in both microglial glycolysis and oxidative phosphorylation. We present data underlining that Fpr2/3 stimulation reverses oAβ-induced ROS production, with a resultant reduction in G6PD activity and the return of homeostatic glycolysis. These oAβ-induced microglial changes triggered the apoptosis of SH-SY5Y cells in co-culture with BV-2 microglia. However, supporting our interest in Fpr2/3 for therapeutic approaches to neurodegenerative diseases, post-treatment with a select agonist for the receptor successfully prevented apoptosis of these neuronal like SH-SY5Y cells. This original data unveils novel functions of Fpr2/3 in the central nervous system (CNS), supplementing the well-established pro-resolving functions the receptor facilitates within the periphery. The combination of pro-resolving, anti-oxidative, immunometabolic and anti-apoptotic functions of Fpr2/3 support the exploitation of this receptor for therapeutic research into multiple different CNS disorders, including AD

Genetic studies of Agastache

Agastache is a genus of perennial plants in the mint family primarily native to North America. This genus produces aromatic oils that are used in foods, drugs, and perfumes. Agastache has also been reported to be a valuable source of nectar for honey bee forage. The genus has gained importance in America, Asia, and Europe as a component of tea mixtures and as a flavoring in confections. Because of the increasing popularity of this genus and our limited base of knowledge about it, this dissertation project was conducted to address questions of how aromatic compounds and isozymes are inherited in A. foeniculum. In addition, the genetic control of anthocyanin production and malate dehydrogenase was investigated in A. rugosa;A comprehensive review of research investigations on the genus Agastache is presented. The review covers morphologic, cytogenetic, and taxonomic studies of Agastache. It also includes references describing biochemical studies of Agastache and others describing the culinary, pharmaceutical, and ornamental applications of this genus;I conducted studies to determine the inheritance of some common aromatic compounds and of isozymes in A. foeniculum. Controlled crosses were made between individuals with different chemotypes and isozyme banding patterns and their F2 progenies were analyzed. Hypotheses describing the genetic control of the production of myrcene, limonene, and methylchavicol and of Cat, Got-2, Pgm-2, Tpi-1, and Tpi-2 were tested. In general, production of the three aromatic compounds controlled by single genes with dominant alleles. Results also revealed that Cat, Got-2, Pgm-2, Tpi-1, and Tpi-2 are each controlled by a single gene with codominant alleles;I also conducted a study to determine the inheritance of anthocyanin production and of malate dehydrogenase banding patterns in A. rugosa. These data also support the hypothesis that each of those traits is controlled by single genes. This is the first report of heritable variability in A. rugosa. In general, the genetic behavior of Agastache is that of a normal diploid species

Phenolics of the Inner Bark of Silver Birch: Characterization and Intraspecific Variation

This thesis describes work related to the in-depth characterization of the phenolic compounds of silver birch (Betula pendula) inner bark. Phenolic compounds are the most ubiquitous class of plant secondary compounds. The unifying feature of this structurally diverse group is an aromatic ring containing at least one hydroxyl group. Due to the structural diversity, phenolics have various roles in the plant defense against biotic and abiotic stresses. In addition, they can confer several health-promoting properties to humans. Furthermore, the structural diversity of this class of compounds causes challenges for their analysis. The study species in the present work, silver birch, is economically the most important hard wood species in northern Europe. Its inner bark contains a high level of phenolic compounds and it has shown one of the strongest antioxidant activities among 92 Finnish plant materials. The literature review surveys the diversity and organ specific distribution of phenolic compounds in silver birch as well as the proposed ecological functions of phenolic compounds in nature. In addition, the basis for the characterization of phenolics by mass spectrometry (MS), nuclear magnetic resonance spectroscopy (NMR), and circular dichroism spectroscopy (CD) are reviewed. The objective of the experimental work was to extract, purify, characterize, and quantify the inner bark phenolic compounds. Overall 36 compounds were characterized by MS and ultraviolet spectroscopy (UV). 24 compounds were isolated and their structures confirmed by NMR and CD spectroscopy. Five novel natural compounds were identified. Special emphasis was placed on the establishment of a method for the characterization of proanthocyanidins (PAs). Hydrophilic interaction liquid chromatography (HILIC) was utilized because of its high resolution power and predictable elution order of oligomeric and polymeric PAs according to an increasing degree of polymerization. The combination of HILIC and high-resolution MS detection allowed the identification of procyanidin (PC) polymers up to the degree of polymerization of 22. In addition, a series of oligomeric and polymeric PC monoxylosides were observed for the first time in nature. Season and genotype influenced the quantities of the main inner bark phenolics, yet qualitative differences were not observed. However, manual wounding of the inner bark induced the production of ellagitannins (ETs) in the wounded tissues, i.e. callus. Since ETs were not detected in the intact inner bark, this finding may reflect the capacity of silver birch to exploit ellagitannins in its defense.Siirretty Doriast

Targeting GDNF receptors with small molecules for the treatment of Parkinson’s disease

Motor symptoms of Parkinson’s disease (PD) are caused by the degeneration of dopamine (DA) neurons. Currently, no disease-modifying therapies against PD are available. Therefore, the major challenge is developing a drug to protect and restore DA neurons. Glial cell line-derived neurotrophic factor (GDNF) has been identified and characterized for its ability to promote the survival of cultured nigrostriatal dopamine neurons and protect and repair them in animal models of PD. However, the outcomes of the clinical trials with GDNF in PD patients remain inconclusive. GDNF is a promising protein that halts neurodegeneration. GDNF does not cross through the blood-brain barrier (BBB) and has poor diffusion properties, complicating clinical use in PD patients. This thesis aimed to characterize the biological activity of GDNF family ligand (GFL) receptor agonists in both in vitro and in vivo preclinical models of PD. We have developed small molecular weight compounds acting similarly to GDNF in the dopamine system (GFL receptor agonist) with improved pharmacological characteristics. The first-generation GFL receptor agonist, a compound named BT13, potently activated the GDNF receptor REarranged during transfection (RET) and its downstream targets. It protected cultured dopamine neurons from neurotoxin-induced cell death and stimulated dopamine release in the mouse striatum. We further optimized BT13 and developed the second-generation GFL receptor agonist BT44 with ten-fold improved potency. BT44 activated RET, supported cultured DA neuron's survival and protected them from neurotoxin lesions, induced functional recovery, and protected striatal dopaminergic fibers in rats with experimentally induced PD. We also studied the selectivity of both BT13 and BT44 using different functional assays. Our results demonstrate that both BT13 and BT44 are selective towards RET. The compounds promote survival and protect the cultured dopamine neurons only in the presence of RET. BT44 is a promising lead compound that could be potentially developed as a drug for PD treatment. However, BT44 suffers from intrinsic poor aqueous solubility like many other hydrophobic drugs, making its preclinical development and clinical translation difficult. Therefore, to improve BT44 solubility, we developed nanoformulation of BT44 with Pox-based ABA triblock copolymers. We found that nanoformulated BT44 retains its biological activity and has improved absorption and blood-brain barrier (BBB) penetration compared to the pristine BT44. We also demonstrate that nanoformulated BT44 binds to the GFL receptors and competes with GDNF for binding to the RET receptor. The receptor binding studies were not possible with pristine BT44 due to its poor solubility. Taken together, our results indicate that both BT13 and BT44 can activate the RET receptor and its downstream signaling cascade necessary for neuronal survival and protection from neurotoxin insults. Further, our results show that in vitro BT44 is active in 10 nM concentrations, which is a realistic target concentration for actual drugs. Moreover, we developed a nanoformulation of BT44 to improve the solubility of the pristine compound and showed that this nanoformulation retains biological activity. With further optimization and detailed studies, BT44 could be developed as a drug-like candidate for disease-modifying treatment for PD.Tiivistelmä ei saatavilla