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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Cultivar and E-Beam irradiation effects on phytochemical content and antioxidant properties of pecan kernels

Villarreal Lozoya, Jose Emilio 15 May 2009 (has links)
Pecan kernels from six cultivars were analyzed for phenolic content and antioxidant properties. In addition, kernels from two cultivars were irradiated with 0, 1.5 and 3.0 kGy using E-Beam irradiation and stored in accelerated conditions (40 °C and 55% R.H.). Changes in phytochemical profile and antioxidant properties were monitored for 134 days. Cultivars differed greatly in their phytochemical content. Total extractable phenolic content (TP) ranged from 62 to 106 milligrams of chlorogenic acid equivalents per gram of defatted kernel. Antioxidant capacity (AC) measured by the DPPH free radical had a strong correlation with TP. Shells from each cultivar were 6, 4.5 and 18 times greater for TP, AC and condensed tannin content (CT). Gallic and ellagic acids, epicatechin and catechin were identified in hydrolyzed extracts of all cultivars. Prior to hydrolysis, no compounds were positively identified. Fatty acid profile of kernel oil had a strong inverse correlation between oleic and linoleic oil. Kernels from the same cultivar but different location differed in their fatty acid composition but had similar TP. Irradiation of â Kanzaâ and â Desirableâ kernels with 1.5 and 3.0 kGy had no detrimental effects on AC and TP by the end of experiments. Phenolic profile was similar for all treatments. Tocopherol content decreased with irradiation treatments, but no further degradation was observed throughout storage. Peroxide values increased slightly after 98 and 134 days of storage for â Desirableâ kernels, with slight differences between controls and irradiated samples. Color of kernels decreased in lightness and yellowness and increased in redness with no differences between irradiated samples and controls. For the first time the effect of pecan cultivar and E-Beam irradiation was assessed in phytochemical and antioxidant attributes of pecan kernels. Additionally, irradiation with E-Beam had no significant detrimental effects in phytochemical composition and only a slight increase in peroxide value, indicating potential as pecan kernel sanitization.
22

Role of mycophenolic acid in kidney transplantation

Yeung, Shing, Joseph, 楊誠 January 2004 (has links)
published_or_final_version / Medicine / Master / Doctor of Medicine
23

A synthetic and spectrometric study of the initial phases in urea-formaldehyde resin formation

Nocanda, Xolani Wittleton January 1998 (has links)
In a series ofpreIiminary studies of urea-formaldehyde reactions, the influence of the U:F molar ratio, the temperature and the catalyst were investigated. Subsequently, in a more rigorous evaluation of the influence of four variables on urea-formaldehyde resin formation, viz., U:F molar ratio, pH, temperature and reaction time, a set of twenty reactions were performed using a statistical approach. The results indicate that high resin viscosity is best achieved by using a high U:F molar ratio (1:2) and conducting the reaction at 90°C. Several basic components produced in urea-formaldehyde reactions have been synthesised, characterised by NMR spectroscopy, silylated using bis(trimethylsilyl)trifluoroacetamide and analysed by low resolution mass spectrometry. The use oftriazones as cross-linking agents has been investigated, and a series of 5-substituted triazones have been prepared and their mass fragmentation patterns explored using a combination of low and high resolution mass spectrometry. In order to facilitate interpretation of ¹³C NMR data obtained for U-F resins, internal rotation in various urea derivatives was investigated using variable temperature ¹H and ¹³C NMR spectroscopic study. Signal splittings observed below 247 K have been rationalised in terms of various rotameric structures.
24

A Comprehensive Study of Phenolics and Peptides from Three Legume Varieties

Zhang, Yan 06 May 2017 (has links)
Lentil, black soybean and black turtle have been proved to be phenolic-rich legume varieties and possess higher antioxidant activity. In this study, the three legume varieties were subjected to broad range of processing conditions, and the effects on phenolic contents, antioxidant capacity and individual phenolic acid were investigated. The results showed all processing methods could decrease the total phenolic content, and steaming processing could preserve more phenolics and antioxidant activity than boiling processing. Phenolic acids mainly existed in nonree form and the content of individual free phenolic acids was dependent on the thermal process applied. When in vitro gastrointestinal simulation digestion was applied to the thermally processed beans, it was found that the properties of hydrolysates including total phenolic content, antioxidant activity, degree of hydrolysis, and ACE (angiotensin converting enzyme) inhibitory activity were all affected by thermal conditions employed. There was a weak correlation between the degree of hydrolysis and ACE inhibition. In the current study, for each legume variety, cooking conditions which yielded the highest phenolic content and antioxidant activity were selected. Phenolics of the raw and cooked seeds from each legume variety were extracted, semi-purified (XAD-7) and further fractionated (Sephadex LH-20). The results showed cooking had great effects on yield, phenolic content, antioxidant capacity, and individual phenolic compounds. The phenolic content and antioxidant activity could be enriched tremendously in the semi-purified extracts and some fractions. Some phenolic compounds which were absent in raw material could be found after cooking in the fractions and some phenolic compounds which were present in raw material disappeared after cooking. Among crude phenolic extracts, semi-purified extracts and fractions, only crude extracts showed ACE inhibition. In addition, protein isolates from the legumes varieties were treated with in vitro GI (gastrointestinal) digestion and then separated by ultrafiltration, DEAE anion exchange chromatography and gel permeation chromatography. After ultrafiltration, the lowest molecular weight fraction (< 3kD) had the highest ACE inhibition and the three legume varieties showed different peptide distribution, ACE inhibition, and antioxidant profile in the hydrolysates. Gel filtration chromatography further revealed that the most potent ACE inhibitors were peptides of 2-5 amino acids long.
25

Proanthocyanidins, anthocyanins and phenolic acids in food barleys of diverse origin

Hambira, Chipo 11 January 2010 (has links)
Phytochemicals found in grains complement those found in fruits and vegetables. These phytochemicals, though minor compounds, contribute to the antioxidant properties which are related to the health benefits associated with the consumption of whole grain. In this thesis project, nine barley genotypes of diverse origin namely CI2230 from Nepal, CI1248 from Israel, 3 Peruvian genotypes; Peru 3, Peru 16 and Peru 35, Hokuto Hadaka from Japan, EX116; a cross between Moroccan and Canadian genotype, EX83; a cross between two Canadian genotypes and EX127; a cross between Canadian and German genotypes were studied. The genotypes were categorized based on appearance into purple, black and yellow grains. Phenolic acids and flavonoids were identified and quantified in these diverse genotypes using HPLC-ESI-MS analysis. The main classes of dietary flavonoids studied in the barleys were anthocyanins and flavan-3-ols. Phenolic acids were identified and quantified (p-coumaric, ferulic, sinapic, caffeic, vanillic). Three ferulic acid dehydrodimers (8-0-4’ DFA, 8-5’ benzofuran form and 5-5’ DFA) were also identified. The most abundant dimeric flavan-3-ols were procyanidins B3 and prodelphinidin B3. The monomeric unit, (+)-catechin, was the most abundant while catechin glucoside (m/z 451) was also identified. Among the Peruvian genotypes, Peru 16 and Peru 35 exhibited relatively high levels of total PA content. Total phenolic content and antioxidant activities of methanolic, acetone and alkali hydrolyzed extracts of the nine barley genotypes was determined by the Folin- Ciocalteau assay, DPPH radical scavenging assay and oxygen radical absorbance capacity (ORAC assay).The acetone extract exhibited the highest antioxidant capacity using all the methods of analysis. Furthermore, dark colored grains were found to exhibit higher contents of phenolic compounds. The phenolic acids, PAs and anthocyanins identified and quantified had significant contribution to the overall antioxidant capacity of the barley whole grain. Four hull-less genotypes namely CI2230, EX127, CI1248 and Peru 35 were further partially sprouted to establish the effects of sprouting on phenolic acid composition. Partial sprouting was observed to significantly increase the soluble conjugated phenolic acids. The barley genotypes studied were found to contain different quantities of phytochemicals and had high proanthocyanidin content thereby rendering them as alternative sources of antioxidants. Barley sprouts present a possible novel food ingredient with improved properties such as phenolic acid composition and other benefits such as easier incorporation into food products under development.
26

Proanthocyanidins, anthocyanins and phenolic acids in food barleys of diverse origin

Hambira, Chipo 11 January 2010 (has links)
Phytochemicals found in grains complement those found in fruits and vegetables. These phytochemicals, though minor compounds, contribute to the antioxidant properties which are related to the health benefits associated with the consumption of whole grain. In this thesis project, nine barley genotypes of diverse origin namely CI2230 from Nepal, CI1248 from Israel, 3 Peruvian genotypes; Peru 3, Peru 16 and Peru 35, Hokuto Hadaka from Japan, EX116; a cross between Moroccan and Canadian genotype, EX83; a cross between two Canadian genotypes and EX127; a cross between Canadian and German genotypes were studied. The genotypes were categorized based on appearance into purple, black and yellow grains. Phenolic acids and flavonoids were identified and quantified in these diverse genotypes using HPLC-ESI-MS analysis. The main classes of dietary flavonoids studied in the barleys were anthocyanins and flavan-3-ols. Phenolic acids were identified and quantified (p-coumaric, ferulic, sinapic, caffeic, vanillic). Three ferulic acid dehydrodimers (8-0-4’ DFA, 8-5’ benzofuran form and 5-5’ DFA) were also identified. The most abundant dimeric flavan-3-ols were procyanidins B3 and prodelphinidin B3. The monomeric unit, (+)-catechin, was the most abundant while catechin glucoside (m/z 451) was also identified. Among the Peruvian genotypes, Peru 16 and Peru 35 exhibited relatively high levels of total PA content. Total phenolic content and antioxidant activities of methanolic, acetone and alkali hydrolyzed extracts of the nine barley genotypes was determined by the Folin- Ciocalteau assay, DPPH radical scavenging assay and oxygen radical absorbance capacity (ORAC assay).The acetone extract exhibited the highest antioxidant capacity using all the methods of analysis. Furthermore, dark colored grains were found to exhibit higher contents of phenolic compounds. The phenolic acids, PAs and anthocyanins identified and quantified had significant contribution to the overall antioxidant capacity of the barley whole grain. Four hull-less genotypes namely CI2230, EX127, CI1248 and Peru 35 were further partially sprouted to establish the effects of sprouting on phenolic acid composition. Partial sprouting was observed to significantly increase the soluble conjugated phenolic acids. The barley genotypes studied were found to contain different quantities of phytochemicals and had high proanthocyanidin content thereby rendering them as alternative sources of antioxidants. Barley sprouts present a possible novel food ingredient with improved properties such as phenolic acid composition and other benefits such as easier incorporation into food products under development.
27

The pro-inflammatory effects of phenols on the skin

Newby, Craig Sinclair January 1999 (has links)
No description available.
28

Vliv kuchyňských úprav na obsah fenolických látek v petrželi zahradní (Petroselinum crispum) / Influence of kitchen treatments on the content of phenolic substances in parsley (Petroselinum crispum)

RAJDLÍKOVÁ, Sylva January 2019 (has links)
The Master's thesis deals with the determination of the total content of phenolic compounds contained in garden parsley (Petroselinum crispum). Specifically, the influence of selected kitchen treatments (drying, boiling) on the content of phenolic compounds of garden parsley was monitored in the following three varieties: Atika, Hanácká, Olomoucká. First, the total polyphenol content was determined by spectrophotometry using Folin-Ciocalteau reagent in fresh parsley extract, further samples were dried and boiled. It was always done separately for root and stem. Thereafter, specific representatives of the phenolic compounds were identified using high performance liquid chromatography from the lyophilized material. The highest concentration of phenolic compounds was found in the dried parsley stem in case of all varieties. The highest content of specific phenolic compounds - apigenin, kaempferol, luteolin was found in the Atika variety, and also in the stems of all the mentioned varieties.
29

Study of therapeutic potential of acid caffeic protocols and diabetes in mice dyslipidemia / Estudo do potencial terapÃutico do Ãcido cafÃico em protocolos de diabetes e dislipidemia em camundongos

Vivianne Machado de AraÃjo 30 April 2014 (has links)
CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / The diabetes and dyslipidemia are important in cardiovascular risk factors. When associated with oxidative stress may accelerate coronary artery disease and progression of atherosclerotic lesions. There are several natural products that stand out as potential therapeutic agents for treatment of such diseases, including caffeic acid, a phenolic compound that has a variety of biological and pharmacological activities described in the literature. Thus, the aim of this study was to evaluate the therapeutic potential of caffeic acid in experimental protocols of diabetes and dyslipidemia, as well as examine their modulating activity under oxidative stress. Hyperlipidemia was induced in male mice using two protocols by means of a single intraperitoneal administration of 400mg/kg Triton WR-1339 and 400mg/kg Poloxamer-407 in all animals, except for the normal control. The treated groups received doses caffeic acid 25 (CA25), 50 (CA50) and 100 mg/kg (CA100). The serum of these animals was analyzed on two different time intervals for total cholesterol, triglycerides and glucose. Liver tissue was analyzed after both protocols dyslipidemia for products of lipid peroxidation, the non-protein sulfhydryl groups (NP-SH) and the antioxidant enzyme superoxide dismutase (SOD). The hypoglycemic activity of caffeic acid was checked by the protocol of diabetes induced by alloxan. Treatment with three doses of caffeic acid and 200mg/Kg fenofibrate significantly reduced total cholesterol and triglyceride levels 24 and 48 hours after induction of dyslipidemia in both protocols dslipidemia. There was also reduced blood glucose at all doses used to induce dyslipidemia with Poloxamer -407. Furthermore, the treatment caused a reduction in the CA and an increase in lipid peroxidation levels of NP -SH in two models of dyslipidemia and in addition, increased levels of SOD-induced hyperlipidemia in Poloxamer-407. Regarding the induction protocol with alloxan diabetes, there was reduction in blood glucose and total cholesterol levels in the three groups treated with caffeic acid. Triglyceride levels were significantly reduced in animals in groups CA25 and CA100. The results suggest that caffeic acid has a beneficial effect in the treatment of dyslipidemia and diabetes, as well as an important antioxidant activity without the presence of adverse effects. However, most studies of chronic so they can ensure the safety and efficacy of its use are needed. / O diabetes e as dislipidemias constituem-se em importantes fatores de risco cardiovascular. Quando associados ao estresse oxidativo podem acelerar a doenÃa arterial coronariana e a progressÃo das lesÃes aterosclerÃticas. Existem vÃrios produtos de origem natural que despontam como potenciais agentes terapÃuticos para tratamentos de tais doenÃas, dentre eles o Ãcido cafeico, um composto fenÃlico que apresenta uma variedade de atividades biolÃgicas e farmacolÃgicas descritas na literatura. Desse modo, o objetivo do presente trabalho foi avaliar o potencial terapÃutico do Ãcido cafeico em protocolos experimentais de diabetes e dislipidemia, bem como analisar sua atividade moduladora sob o estresse oxidativo. A hiperlipidemia foi induzida em camundongos machos atravÃs de dois protocolos, sendo mediante uma Ãnica administraÃÃo intraperitoneal de 400mg/Kg de Triton WR-1339 e 400mg/Kg de Poloxamer-407 em todos os animais, exceto no controle normal.Os grupos tratados com Ãcido cafeico receberam as doses de 25 (AC25), 50 (AC50) e 100 mg/Kg (AC100). O soro desses animais foi analisado em dois intervalos de tempos diferentes para colesterol total, triglicerÃdeos e glicose. JÃ o tecido hepÃtico foi analisado apÃs ambos os protocolos de dislipidemia para os produtos de peroxidaÃÃo lipÃdica, os grupos sulfidrÃlicos nÃo-proteÃcos (NP-SH) e a enzima antioxidante superÃxido dismutase (SOD). A atividade hipoglicÃmica do Ãcido cafeico foi verificada atravÃs do protocolo de diabetes induzida por aloxano. O tratamento com as trÃs doses de Ãcido cafeico e fenofibrato 200mg/Kg reduziram significativamente os nÃveis de colesterol total e triglicerÃdeos 24 e 48 horas apÃs a induÃÃo da dislipidemia em ambos os protocolos de dslipidemia. Houve tambÃm reduÃÃo da glicose sanguÃnea em todas as doses utilizadas ao se induzir a dislipidemia com o Poloxamer-407. AlÃm disso, o tratamento com AC promoveu diminuiÃÃo da peroxidaÃÃo lipÃdica e aumento nos nÃveis de NP-SH nos dois modelos de dislipidemia e, adicionalmente, aumento nos nÃveis de SOD na hiperlipidemia induzida por Poloxamer-407. Em relaÃÃo ao protocolo de induÃÃo de diabetes com aloxano, verificou-se reduÃÃo da glicemia e do colesterol total nos trÃs grupos tratados com Ãcido cafeico. JÃ os nÃveis de triglicerÃdeos foram reduzidos significativamente nos animais dos grupos AC25 e AC100. Os resultados obtidos sugerem que o Ãcido cafeico possui um efeito benÃfico no tratamento das dislipidemias e do diabetes, alÃm de uma importante atividade antioxidante, sem a presenÃa de efeitos adversos durante o estudo. No entanto, sÃo necessÃrios mais estudos de forma crÃnica que possam garantir a seguranÃa e eficÃcia de sua utilizaÃÃo.
30

Applications of Metal Phenolic Networks as Coatings for Controlled Drug Delivery and Membrane Modification

January 2019 (has links)
archives@tulane.edu / N/A / 1 / Savannah Steadman

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