Browsing by Subject "Bioavailability"

Now showing 1 - 5 of 5
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    Bioavailability and Biological Efficacy of Phenolic Compounds in Oat and Extra Virgin Olive Oil: Implication of Exercise
    (2018-07) Zhang, Tianou
    Eccentric exercise and atherosclerosis are known to generate reactive oxygen and nitrogen species (RONS) and inflict inflammatory responses, leading to muscle inflammation and coronary artery disease respectively. Selective phenolic compounds from oats (Avenanthramides, AVA) and olive oil (Oleocanthal/Oleacein, Oleo/Olea) have been shown to remove these chemicals and inhibit the progress of inflammation. This dissertation proposed three studies to investigate: (1) The metabolic fate of AVA by measuring plasma concentrations and pharmacokinetic properties of AVA in human after an acute oral ingestion of oat cookies. (2) Whether 8 weeks of dietary supplementation of AVA can affect circulatory immune cells and reduce blood inflammatory markers in response to downhill running (DR) induced muscle inflammation in both male and female subjects. (3) Whether 12 weeks of Oleo/Olea supplementation can inhibit inflammation and endothelial dysfunction in atherosclerotic rats, and combined exercise training would further reduce inflammation and improve immune functions. The findings and conclusions are: (1) AVA found naturally in oats are absorbed in the plasma after oral administration in humans. AVA reach peak plasma concertation 2-3 hours after oral ingestion in human. AVA-B has the slowest elimination rate (Kel) and longest half-life (T1/2) compared to AVA-A and AVA-C, while AVA-C demonstrated the lowest plasma concentrations (Cmax). (2) Oat AVA supplementation reduced circulatory inflammatory cytokine (IL-6) expression and ROS generation (NRB) after DR. AVA in oats also inhibited expression of chemokines (MIP-1β, MCP-1), cell adhesion molecule (VCAM-1) and colony stimulating factors (GM-CSF, G-CSF) induced by DR. Although circulatory immune cells were not affected by oat AVA supplementation, oat supplementation decreased circulatory monocytes activation (CD14+) while oat AVA inhibited neutrophils (CD11b+) and increased NK cells (CD56+) activation after DR. (3) High Oleo/Olea diet tends to increase circulatory leukocytes, granulocytes, neutrophils percentage and inflammatory cytokines (MCP-1, RANTES, NAP-3, M-CSF, GM-CSF) but decrease lymphocytes percentage and anti-inflammatory cytokines (IL-10) in sedentary rats, whereas exercise training significantly reversed these trends of immune markers induced by EVOO supplementation.
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    The biodegradation and microbiological impacts of micropollutants in methanogenic communities
    (2012-12) McNamara, Patrick Joseph
    Pervasive usage of chemicals generates micropollutants throughout the environment. Anaerobic environments in particular accumulate high levels of hydrophobic micropollutants, and it is estimated that over 200 metric tons of micropollutants are discharged with biosolids each year. It is important to understand how treatment processes impact the fate of micropollutants as well as understand how micropollutants impact microbiological communities so that environmental risks can be minimized. This research elucidated the impact of an emerging treatment process, thermal-hydrolysis coupled to mesophilic anaerobic digestion (TH-MAD), on the fate of nonylphenol ethoxylates as well as the impacts of triclosan and perfluorooctane sulfonate (PFOS) on methanogenic community structure and function. The TH-MAD process inhibited biodegradation of nonylphenol ethoxylates to nonylphenol relative to MAD with no pretreatment. Indeed, the ratio of nonylphenol to the sum of nonylphenol ethoxylates + nonylphenol only increased by 24.6±3.1% in TH-MAD reactors compared to a 56% increase following MAD treatment. While post-aerobic treatment did reduce the sum of nonylphenol ethoxylates + nonylphenol, and concomitantly reduced estrogenicity, this research implied that source control is likely the most efficient option for removing these micropollutants. Triclosan is another wide-spread micropollutant that is persistent under anaerobic conditions. Triclosan is an antimicrobial agent that could therefore impact environmental systems that rely on healthy functioning of microorganisms. Methanogenic communities with no previous exposure to triclosan were able to adapt to triclosan at environmentally relevant levels and maintain function. When previously-exposed communities were exposed to triclosan at 4x current detected environmental levels, community structure shifted and methane production was inhibited. These levels of triclosan also selected for mexB, a gene that confers multidrug resistance, in previously unexposed communities. Lastly, PFOS was found to directly impact methanogenic communities and augment the impacts of triclosan in long-term exposure studies (140 days), but not in short-term (14 day) exposure studies.
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    Improving the functionality and bioactivity of wheat bran.
    (2012-04) Petrofsky, Keith Eric
    Wheat bran, including the aleurone layer, contains the vast majority of phenolic antioxidants found in the wheat kernel. Unfortunately, about 80% of phenolic acids in wheat bran are structurally bound and insoluble. These bound phenolics are neither bioactive nor bioavailable during digestion. Additionally, wheat bran contains 43% total dietary fiber, but only 3% soluble dietary fiber. Insoluble fiber is less functional than soluble fiber which has been shown to lower cholesterol and regulate blood sugar. We hypothesized that processing could improve the functionality of wheat bran and bioavailability of phytochemicals in the bran. Specifically, we aimed to maximize the physical properties of viscosity and water hydration capacity in wheat bran, while also maximizing the release of bound phenolic antioxidants from the bran. Wheat bran processing included physical treatments of dry grinding, high shear mixing, high pressure homogenization (HPH), and alkali chemical treatments with different concentration, time, and temperature. Sample analysis included particle size, Wheat bran, including the aleurone layer, contains the vast majority of phenolic antioxidants found in the wheat kernel. Unfortunately, about 80% of phenolic acids in wheat bran are structurally bound and insoluble. These bound phenolics are neither bioactive nor bioavailable during digestion. Additionally, wheat bran contains 43% total dietary fiber, but only 3% soluble dietary fiber. Insoluble fiber is less functional than soluble fiber which has been shown to lower cholesterol and regulate blood sugar. We hypothesized that processing could improve the functionality of wheat bran and bioavailability of phytochemicals in the bran. Specifically, we aimed to maximize the physical properties of viscosity and water hydration capacity in wheat bran, while also maximizing the release of bound phenolic antioxidants from the bran. Wheat bran processing included physical treatments of dry grinding, high shear mixing, high pressure homogenization (HPH), and alkali chemical treatments with different concentration, time, and temperature. Sample analysis included particle size, viscosity, water hydration capacity (WHC), water extractable material (Wa-Ex), free phenolics, and visual imaging by scanning electron microscopy (SEM). Prescreening results showed that while HPH helped reduce particle size of bran regardless of treatment, only alkali chemical treatments released the vast majority of bound phenolics. Alkali treatments also contributed to viscosity increase, with interaction of variables of alkali concentration, treatment time, and temperature. Variables for optimization studies included bran grind, alkali concentration, reaction time, and reaction temperature, while process treatments that remained constant were high shear mixing after chemical pretreatment and HPH conditions. Two factorial designs were conducted to optimize viscosity and WHC of bran while maximizing release of bound phenolics. The second factorial design was an augmentation to the first and data was combined for statistical analysis. Viscosity maximum was reached using 0.5mm screen size in bran dry grinding and chemical treatment conditions of 60°C soak temp, 24 hour soak time, 0.1N NaOH concentration. WHC maximum was reached using 0.5mm screen size in bran dry grinding and chemical treatment conditions of 48°C soak temp, 20 hour soak time, 0.7N NaOH concentration. Overall, process optimization was successful and produced wheat bran with a 500% increase in viscosity, 200% increase in WHC, 500% increase in soluble fiber, and a 300 fold increase in free and soluble bound phenolic antioxidants. Visual confirmation by SEM validated analysis results and showed the optimized bran had a very open and porous structure due to the chemical weakening of the alkali treatment and high shear pulverization of the HPH treatment. The optimized viscosity process was scaled up to produce a large quantity of samples for further research in this collaborative study. Work to separate or concentrate the soluble fraction of processed bran utilized centrifugation to produce additional samples of more soluble and more insoluble processed bran fractions.
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    Malonyl- conjugates of isoflavones: structure, bioavailability and chemical modifications during processing
    (2013-09) Yerramsetty, Vamsidhar
    Soy isoflavones are often associated with prevention of cancer, cardiovascular diseases, osteoporosis, and postmenopausal symptoms. However, the demonstration of theses physiological effects is highly inconsistent. Not all soy foods deliver the same isoflavone-associated benefits. Inconsistency in isoflavone research is partly attributed to the inadequate profiling of isoflavones, lack of standardization of the source of isoflavones, and lack of standard analytical methods for profiling and quantifying isoflavones present in different soy matrices. We are convinced that inconsistent results are due to differences in the bioavailability of the different isoflavone forms consumed. Since isoflavones in soy foods differ in their forms (e.g. conjugated and non-conjugated), large differences may exist in their bioavailability. Therefore, it is crucial to adequately profile the administered isoflavones and study the effect of their conjugation on their bioavailability. Additionally, isomerization of different isoflavone forms occurs upon thermal processing. Complete structural elucidation of the isomers and determination of their thermal stability in soy systems are important for understanding their physiological relevance. Therefore, the overall objective of this study was to determine effect of processing on the chemical modifications of isoflavones and to detect all biologically relevant forms, together with providing adequate and reliable bioavailability data for each of the most abundant isoflavone forms. Isoflavones were extracted from soy grits and were separated and isolated using semi-preparative liquid chromatography. Identification of the different isoflavones forms and isomers was accomplished based on UV wave scan, mass spectrometry, and nuclear magnetic resonance (NMR) analysis. Effect of thermal processing on isomer stability was determined by subjecting soymilk to thermal treatment at 100°C for time intervals ranging from 1 to 60 min. A rapid analytical procedure was developed to quantify isoflavones in biological fluids using stable isotope dilution mass spectrometry (SID-LCMS). Two novel isotopically labeled (SIL) analogues of natural SERMs, genistein and daidzein were synthesized using a H/D exchange reaction mechanism. Computational chemistry coupled with MS and NMR data confirmed the site and mechanism of deuteration. The developed method was sensitive, selective, precise and accurate. Bioavailability of malonylglucosides and their respective non-conjugated glucosides was determined in a model rat system. Rats were gavaged with an assigned isoflavone form. Blood and urine samples were collected at different time intervals. Different isoflavone metabolites in plasma were determined using the developed SID-LCMS method. Bioavailability was determined by calculating pharmokinetic parameters, assuming first order disposition kinetics. NMR characterization of the malonylglucoside isomers revealed its structure to be 4"-O-malonylglucosides, suggesting a malonyl migration from the glucose-6-position to the glucose-4-position. The malonylgenistin isomer represented 6-9 % of the total calculated genistein content in soymilk heated at 100°C for various periods of time. Based on rat peak plasma and urine levels and area under the curve (AUC) of the aglycone post ingestion of the respective isoflavones, it was quite evident that the malonylglucosides were significantly (P ≤ 0.05) less bioavailable than their non-conjugated counterparts. The present work provided full elucidation of the chemical structure of malonylglucoside isomers. We demonstrated for the first time that the formation of the malonylisomers is governed by thermal processing time in a soymilk system. Disregarding the isomer formation upon heating can result in overestimation of loss in total isoflavone content and misinterpretation of the biological contributions. Additionally, this work provided a validated analytical SID-LC/MS method to detect natural and known synthetic selective estrogen receptor modulators (SERMs) in a single analytical assay. Finally, this work differentiated for the first time the bioavailability of malonylglucosides as compared to their non-conjugated counterparts. The observed differences explained to a significant extent the controversy in isoflavone research. We believe that the results of this work will help streamline the experimental approach undertaken by various researchers to achieve consistent clinical conclusions and to optimize the processing parameters that result in the most bioavailable isoflavone profile, thus maximizing their health benefits.
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    Synthesis and Evaluation of Transvalencin Analogues and Adenylation Inhibitors as Antitubercular Agents and Chemical Probes
    (2013-06) Nelson, Kathryn Marie
    >Mycobacterium tuberculosis (Mtb), the etiological agent of pulmonary tuberculosis, is the leading cause of death due to an infectious disease worldwide. Due to a lack of new drug development, poor fidelity to currently available therapeutics, and repeated exposure to therapeutics, Mtb has become multidrug resistant, extensively drug resistant, and even totally drug resistant in some patients. With nearly 9 million deaths and 1.4 million new cases reported by the World Health Organization (WHO) in 2011, new therapeutics that act by novel mechanisms of action are desperately needed to fight this global health threat. Herein we describe our efforts to develop new antitubercular agents by attacking the bacteria's need for iron. This approach involves the inhibition of the biosynthetic pathway to produce siderophores, small molecule iron chelators responsible for acquiring iron in limiting conditions, such as a human host. A prototypical inhibitor of the initiating enzyme in this pathway, MbtA, had previously been developed by our lab, and was used to develop a small set of analogues for in vivo evaluation. We employed Sprague-Dawley rats to evaluate the oral bioavailability of our compounds, revealing that the pKa of the linker nitrogen of the scaffold had a large effect on compound permeability.In addition, we studied the mechanism of action of our parent inhibitor, Sal-AMS, through the development of a photoaffinity probe to label and pull down proteins for target identification. A probe containing a benzophenone moiety for photo-crosslinking and a small alkyne handle for attachment of an imaging or enrichment tag was successfully synthesized. This probe was successful in identifying the intended enzyme of interest (MbtA) as a binding partner, but did not yield any additional hits, suggesting Sal-AMS is a highly specific inhibitor. We also studied a natural product, transvalencin Z, that had been reported as selective against mycobacteria. This compound was very similar in structure to the mycobactins from Mtb, suggesting that it might interfere with iron acquisition or homeostasis. We successfully synthesized the 4 possible diastereomers of the reported structure in an attempt to define the absolute stereochemistry of the natural product, but were unable to match spectroscopic data to the literature report. We attempted to confirm the true stereochemistry through activity testing, but again found our negative results to be in stark contrast to those reported by the discovery group. Finally, we aided a collaborator in the development and synthesis of a probe against DhbE in Bacillus subtilis. Dr. Jun Yin of the University of Chicago was studying the substrate specificity of adenylation domains, and chose an enzyme highly homologous to our target MbtA. We designed a probe that incorporated a similar inhibitor, DHB-AMS, and a long flexible linker with a biotin attached for Dr. Yin's unique yeast cell display assay. Dr. Yin was able to utilize these probes to successfully identify mutant adenylation enzymes with altered specificity towards nonnative substrates. This technique is an exciting new way to potentially access analogues of natural products through manipulation of the biosynthetic machinery, instead of through the organic chemist. These studies have continued to advance our understanding of a new mechanism of action against Mtb, and have brought us one step closer to a preclinical candidate.