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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.
81

Extractability Profiling and Antioxidant Activity of Flavonoids in Sorghum Grain and Non-grain Materials

Njongmeta, Nenge Lynda A. 2009 May 1900 (has links)
Grains, leaves, sheaths, glumes and stalks of sorghum varieties were analyzed for total phenols, condensed tannins, flavan-4-ols, anthocyanins and in vitro antioxidant activity. Black sorghum bran was used to evaluate the effectiveness of organic acids and enzymes on extractability of phenols. Flavonoid profiles of grains and non-grain tissues were determined and characterized using HPLC-PDA and HPLC-ESI-MSn. The presence of a pigmented testa and spreader genes (B1B2S) is a predictor for polymeric flavonoids (tannins) but not for simple phenols such as flavan-4-ols, 3-deoxyanthocyanins, flavones and flavanones. Simple flavonoids increased antioxidant capacity of sorghum, and were present in all sorghum except for the white pericarp sorghums that did not have flavanones. The "red turning into black" gene increased phenols in Type I sorghum. The leaves, sheath and glumes of sorghum had higher levels of phenols (78-600 times more), with in vitro antioxidant properties than commonly seen in grains. Pigmentation of plant components increased levels of 3- deoxyanthocyanins but not flavones nor flavanones. The leaves of biomass sorghum, Collier variety, had 3.4 times more 3-deoxyanthocyanins than the leaves of Tx430 Black x Sumac which had the highest levels (1810 ?g/g) of 3- deoxyanthocyanins among the leaves. The use of 1% HCl/ethanol provides a possible food grade substitute solvent for 1%HCl/methanol in the extraction of phenolic compounds from sorghum. All enzymes evaluated broke down bran particles forming a gel-like material which had increased phenols and antioxidant activities but not 3- deoxyanthocyanins as revealed by HPLC analysis. Microscopy examination showed the gel matrix rich in fiber and can possibly be used for nutraceutical applications. Careful understanding of enzyme activities is necessary for effective extraction of 3-deoxyanthocyanins from sorghum. Sorghum leaves, sheaths and glumes are excellent sources of bioactive compounds, up to 600 times more than the grains of some varieties. Sorghum with the "red turning to black genes" is a potential source of 3- deoxyanthocyanins and flavan-4-ols. With the trend towards sorghum as biomass for ethanol production, plant breeders must select special traits aimed at developing enhanced desired functionality such as antioxidant potential and other healthy attributes with application in food, pharmaceutical/nutraceutical and cosmetic industries.
82

Investigation For Natural Extract Inhibitors Of Bovine Lens Aldose Reductase Responsible For The Formation Of Diabetis Dependent Cataract

Onay, Melih 01 August 2008 (has links) (PDF)
In the polyol pathway, Aldose reductase (AR) is an important enzyme in reduction of aldehydes and aldosugars to their suitable alcohols. AR, using NADPH as a coenzyme, has a molecular weight of 37 000 dalton. AR in its activated form, known to increase the sorbitol accumulation in lens, is responsible for the cataract formation in diabetis diseases. Therefore, the inhibition of aldose reductase is important to prevent the incedence of cataract formation in diabetus mellitus. In the treatment of diabetis dependent cataract, chemically synthetized drugs were sometimes less than beneficial due to the severe side effects they cause. Recently a huge amount of study has been intensified on developing new drugs from natural compounds and even by utilizing plant extracts for their easily metabolizing polyphenolic compounds. In this study, BLAR, source of enzyme, was obtained as crude via differential centrifugation and ammonium sulfate precipitation. The enzyme assay conditions were optimized for the protein, substrate, coenzyme, and salt concentrations, also for the effects of pH and temperature. Ocimum basilicum, Lavandula stoechas, Melissa officinalis, Glycyrrhiza glabra L. and Tilia tomentosa were selected as commonly used alternative medicine plants. Plant extracts were prepared in ethanol and ethyl acetate and their inhibitory effects were tested on crude bovin lens aldose reductase enzyme. Fifty percent inhibitory concentrations (IC50) were found between values of 25.53 &micro / g/mL and 54.15 &micro / g/mL for ethanol extracts and between 41.55 &micro / g/mL and 82.96 &micro / g/mL for the ethyl acetate extracts of selected plants. In addition, the plant extracts were also characterized for their antioxidant activities by of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method and test of total phenolic content (TPC) .
83

Microwave Extraction Of Phenolic Compounds From Caper And Oleaster

Durmaz, Ezgi 01 July 2012 (has links) (PDF)
The main objective of this study was to extract phenolic compounds from caper and oleaster by using microwave. The effects of microwave power (400 and 700 W), extraction time (5-20 min), solid to solvent ratio (1:10, 1:20 and 1:30) and solvent type (water, ethanol and different ratios of ethanol-water mixture) on total phenolic content, antioxidant activity and concentration of the phenolic compounds in the extracts were investigated. In conventional extraction, extraction time and solvent type were used as independent variables. Microwave extraction was compared with conventional extraction. In caper and oleaster extracts that were obtained by using microwave, total phenolic compounds ranged between 5.0-52.4 and 2.6-43.0 mg GAE/g dry material while the antioxidant activity were between 0.5-2.0 and 0.2-3.7 mg DPPH/g dry material, respectively. Higher total phenolic content was observed with increasing solvent amount. The highest total phenolic content was obtained when 50% ethanol-water mixture was used as solvent. Microwave power did not affect total phenolic content significantly. The highest total phenolic contents were obtained when 400 W microwave power, 50% ethanol-water mixture and solid to solvent ratio of 1:30 were used in the extraction from both caper and oleaster. The best extraction time for caper was 5 min while it was 15 min for oleaster. The main constituents were rutin and kaempferol for both caper and oleaster extracts. For caper and oleaster there was no difference between extraction methods in terms of concentration of phenolic compounds. However, extraction time decreased significantly by using microwave, as compared to conventional extraction.
84

In vivo μελέτη της αντιοξειδωτικής δράσης των στύλων του Crocus sativus

Δημακοπούλου, Ανδριάνα 30 March 2009 (has links)
Στόχος της παρούσας μελέτης ήταν να διερευνηθεί η επίδραση αρχικά του σεληνιώδους νατρίου και κατόπιν του εκχυλίσματος των στύλων του Crocus sativus στον καταρράκτη, καθώς και σε βιοχημικές παραμέτρους του φακού, του ήπατος και διαφορετικών εγκεφαλικών περιοχών νεογνών επίμυων. Συγκεκριμένα, προσδιορίστηκε η αντιοξειδωτική ικανότητα και η συγκέντρωση του περιεχόμενου ασκορβικού οξέος του φακού, του ήπατος, του εγκεφαλικού φλοιού και της παρεγκεφαλίδας, ενώ μελετήθηκε και η υπεροξείδωση λιπιδίων των παραπάνω περιοχών. Επιπλέον, πραγματοποιήθηκε και συγκριτική μελέτη των εγκεφαλικών περιοχών των επίμυων-μαρτύρων ως προς την αντιοξειδωτική τους ισχύ και την απόκρισή τους στο οξειδωτικό στρες. / Impact of Crocus sativus stigmas' extract in selenite-induced rats.
85

Antioksidacinio poveikio preparatų su juodųjų serbentų (Ribes nigrum L.) uogų ekstraktu tyrimas ir vertinimas / Development and evaluation of antioxidant preparations containing black currant (Ribes nigrum L.) berries extract

Kasparavičienė, Giedrė 26 January 2006 (has links)
Growing numbers of morbidity and mortality due to the cancer and coronary heart disease is recognized as the increasing challenge in the world. The initial stage of these diseases, early diagnosis and treatment are the main objectives of current researches. According to Lithuanian Health Information Centre morbidity and mortality due to these diseases in Lithuania exceed average of European Union. The oxidative stress occurs in cells as a result of normal physiological processes and environmental interactions, and the complex antioxidant defense system are of particular importance in protecting biological systems against oxidative damage by free radicals. Recently polyphenols and anthocyanins containing foods and preparations have attracted attention due to their health promoting benefits. Anthocyanins make one of the main groups of flavonoids, and represent polyphenolic compounds, that are found in vegetables and fruits, particularly in berries. An important effect of anthocyanins is the scavenging of oxygen-derived free radicals. They can interfere with few different free radical-producing systems, and can increase the function of the endogenous antioxidants. The aim of the research is to choose sources for the products with antioxidant activity from plants cultivated in Lithuania, evaluate quality and antioxidant activity of black currant, red currant and chokeberry products, to develop and evaluate technologies of phytopharmaceuticals with antioxidant activity... [to full text]
86

Lietuvoje augančių Potentilla genties augalų fitocheminė analizė bei vartojimo galimybių tyrimai in vitro / Phytochemical analysis of in Lithuania growing Potentilla genus plants and using possibilities in vitro

Eigirdaitė, Vaida 03 August 2007 (has links)
Fitoterapija (gr. phyton – augalas, therapeia – gydymas) – tai ligų profilaktika ir gydymas, vartojant augalų dalis ar jų preparatus. Nuo seno lietuvių liaudies medicinoje gerai žinomi sidabražolinių (Potentilla) genties augalai. Lietuvoje auga 17 Potentilla genties augalų rūšių, kai kurios iš jų kultūrinės. Šio darbo tikslas yra atlikti biologiškai veiklių medžiagų – flavonoidų ir raugų – išskyrimą iš Potentilla genties augalų (Potentilla anserina L., Potentilla erecta L., Potentilla fruticosa L.) nustatyti veikliųjų medžiagų kiekio kitimus skirtingu augalų vegetacijos metu (birželio – rugsėjo mėnesiais) ir atlikti šių augalinių žaliavų antioksidacinio bei antimikrobinio poveikio tyrimus. Tyrimo medžiaga ir metodai. Tyrime naudota Potentilla genties augalinė žaliava surinkta Šiaulių rajone, Gruzdžių miške (P.anserina žolė, P.erecta šakniastiebiai ir žolė) bei Šiaulių universiteto botanikos sode (P.fruticosa žolė). Permanganatometrinio titravimo metodu buvo nustatytas rauginių medžiagų kiekis tirtuose Potentilla genties augalinėse žaliavose. Naudojant parūgštintą vandenilio chlorido rūgštimi 70% etanolį ir 70% etanolį spektrofotometriniu ir efektyviosios skysčių chromatografijos (ESC) metodu buvo nustatyti bendri flavonoidų kiekiai tirtose augalinėse žaliavose. Antioksidaciniam aktyvumui įvertinti buvo taikomas fotometrinis 2,2-difenil-1-pikrilhidrazilo (DPPH•) laisvojo radikalo sujungimo metodas. Antimikrobinis poveikis įvertintas atliekant tyrimus su triptozės sojos agare 2... [toliau žr. visą tekstą] / Phytotherapy (Greek origin phyton – plant, therapeia – treatment) means the prevention of disease and medical treatment using parts of plants or their extracts. Since ancient times Cinquefoil (Potentilla) family plants have been well-known in Lithuanian non-traditional medicine, comprising over 17 species, some of them are cultivated. Aims and Objectives. To extract biologically active substances – flavonoids and tannins – from Potentilla plants (Potentilla anserina L., Potentilla erecta L., Potentilla fruticosa L.) in order to determine the quantity changes at different times of plant vegetation (June – September), and to research antioxidant and antibacterial effect of those plants. Materials and Methods. Potentilla raw material was collected in the region of Šiauliai, Gruzdžiai forest (Herba Potentillae anserinae, Rhizoma et herba Potentillae erectae) and Šiauliai University Botanical Garden (Folium cum flore Potentillae fruticosae). Permanganatometric titration method was used to find out how much tannin the selected Potentilla contained. Also, spectrophotometric and HPLC methods allowed to measure flavonoid while using 70% of ethanol with hydrochloric acid and 70% of ethanol in the raw vegetation. To evaluate the anti-oxidizing activity photometric 2,2-difenil-1-pikrilhydrosil (DPPH•) free radical method was applied. Antibacterial impact was evaluated with triptosis on soya crop in a hangar for 24 hours at 35 - 37º C using cultivated microorganisms. Results. The tested... [to full text]
87

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.
88

Antioxidant properties of spaghetti and infant cereals and characterization of major phenolic compounds by LC/MS analysis

Hirawan, Rhanissa 08 April 2011 (has links)
The present study investigated the antioxidant properties of commercial regular- and whole- wheat spaghetti. The antioxidant properties comprise the total phenolic content, DPPH radical scavenging activity, oxygen radical absorbance capacity. The contents of ferulic acid, C-glycosyl flavones and SDG were measured by using LC/MS techniques. Whole wheat spaghetti showed significantly higher TPC and ORAC. The contents of ferulic acid, C-glycosyl flavones and SDG were significantly higher in whole wheat spaghetti. The TPC was found to decrease 48 – 78% after cooking. The results showed that consumption of whole grain is strongly recommended. The present study also compared the antioxidant properties of commercial infant cereals. Purple wheat and red rice were used in making home-made and lab-made infant cereals. Pigmented infant cereals showed higher TPC, total anthocyanin content (TAC) and ORAC then brown rice and commercial ones. Anthocyanins were found only in purple wheat while a C-glycosyl flavone was found at higher levels in purple wheat than in red rice samples. Home-made samples did not show significant differences in TPC, TAC and ORAC with lab-made ones; however, the contents of anthocyanins and C-glycosyl flavones were significantly different. Home-made purple wheat infant cereals showed higher cellular antioxidant activity (CAA) than lab-made purple wheat, red rice and commercial ones. Whole purple wheat holds potential to improve the antioxidant properties of infant cereals.
89

Effects of in vitro gastrointestinal digestion on extractability of nutrient and bioactive compounds from wheat bran

Golom, Sirak Tsegai 06 January 2012 (has links)
A static in vitro digestion method was developed as a strategy to understand the effects of modelled digestion on the solubility of nutrients and selected bioactive compounds of autoclaved and untreated wheat bran. Brans from common soft, hard, and durum wheats were evaluated. Results indicated that the in vitro digestion protocol was suitable and effective. Effects of gastrointestinal simulation were considerably larger than gastric digestion alone. Digestibility of the brans ranged from 28.1 to 47.9%. Digestibility of bran minerals, starch and protein was substantial compared to lesser, but still significant, effects on fibre. Fibre solubility was significantly enhanced due to autoclaving. Total phenolic content, free radical scavenging and metal chelation activity were all substantially increased in soluble digests. Yields of these factors indicated that digestion of wheat bran releases ample levels of antioxidants that would be available for absorption in the small intestine to promote beneficial health effects.
90

Antioxidant properties of alkaline extracts from insoluble and soluble dietary fibre derived from selected whole-grain cereals

Guo, Weiwei 23 August 2012 (has links)
The extraction yields of insoluble dietary fibre (IDF) and soluble dietary fibre (SDF) from seven whole-grain cereals (WG) ranged from 11.73% to 23.71% and 2.28% to 5.15%, respectively. Eight monomeric phenolic acids and four diferulic acids were identified and quantified in cereal alkaline extracts by reversed phase high performance liquid chromatography coupled with quadrupole - time of flight mass spectrometry. IDF alkaline extracts had significantly (p < 0.05) higher levels of total phenolic content (TPC) and DPPH radical scavenging activity than WG and SDF extracts. Corn IDF (C-IDF) extracts exhibited the highest TPC and DPPH, followed by red rice. MTT cell viability assay indicated that 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) or xanthine-xanthine oxidase (X-XO) induced cell loss can be effectively reduced by pre-incubating Caco-2BBe or FHs 74 Int cells with certain levels of C-IDF extracts. This effect was speculated to be associated with the antioxidant activity of C-IDF linked phenolic compounds.

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