Cataract disease affects millions of people worldwide. It is characterized by the accumulation of light-scattering bodies within the lens that reduce visual acuity. Cataracts are effectively treated surgically, but at great expense, costing Medicare $3.4 billion in 1997. Development of an alternative therapy for this disease would provide medical and economic benefits. We have investigated a novel antioxidant, the superoxide scavenger Mn(III)-salophen, as a therapeutic agent in the selenite cataract model. Mn(III)-salophen has been shown to protect E. coli colonies against oxidative stress but was untested in a eukaryotic system. A total dose of 300 mmol/kg, given IP in four equal 75 mmol/kg doses spaced four hours apart, protects 75% of neonatal rats from nuclear cataract development five days after selenite injection. Selenite is toxic through its reaction with the endogenous antioxidant glutathione (GSH). The reduction of selenite to selenide through an intermediate, selenodiglutathione (GSSeSG) leads to generation of superoxide radical, one of several toxic oxygen species that can damage the lens. Mn(III)-salophen causes an in vitro preservation of the lifetime of GSSeSG by interrupting the reduction of selenite. We have established that the reduction of GSSeSG to selenide does not use GSH as a reducing agent, but rather depends upon electrons generated in the earlier reduction of selenite to selenodiglutathione. These electrons can be intercepted by known one-electron scavengers, arresting the metabolism of GSSeSG. Extensive proteolysis of lens crystallins and loss of calcium homeostasis occur in cataractous lenses from a rat treated with sodium selenite. The visual protection with Mn(III)-salophen is accompanied by a partial loss of the calcium homeostasis, a net increase in sodium, and calpain-mediated proteolysis of à -crystallins similar to lenses from animals treated with selenite alone. Although preservation of alpha-crystallins may contribute to the greater transparency in the protected lens, generalized à -crystallin proteolysis is insufficient for cataract formation. From these experiments we propose that Mn(III)-salophen minimizes the oxidative stress imposed upon the cell by interfering with the metabolism of selenodiglutathione. This allows the cell to compensate for the loss of cation homeostasis and prevents aggregation of proteolyzed crystallins into cataracts. / Ph. D.

The effect of soy as a natural antioxidant against flaxseed rancidity in yeast breads was tested. Variables included: control (100% bread flour); yeast bread with 15% flax meal in place of part of the total bread flour; yeast bread with 15% flax meal and 5% soy; and yeast bread with 15% flax meal and 10% soy. Objective and sensory tests were used to evaluate breads. Peroxide values indicated that the hydroperoxides in breads increased during the first four weeks of the study, and then decreased, as would be expected as breads are exposed to more elements with time. Moisture content was not significantly different between the breads. Breads containing flax were significantly firmer (p < 0.02) in texture. Breads containing flax were also significantly lower in volume (p < 0.005) and significantly darker in crumb color (p < 0.01). The level of 10% soy contributed to a significantly darker crust color (p < 0.04). Quantitative descriptive analysis (QDA) found the level of 10% soy also contributed to an increased stale taste and aftertaste, firmer texture, coarser crumb, and drier loaf (p < 0.05). Musty aroma was not significantly different among breads and all breads containing flax had an increased grainy taste (p < 0.0001). Soy was found to have no significant antioxidant effect on the prevention of flaxseed rancidity in yeast breads. / Master of Science

Orientador: Neura Bragagnolo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-10-03T13:46:21Z (GMT). No. of bitstreams: 1 Alves_AdrianaBarreto_D.pdf: 4493430 bytes, checksum: b528cf0688daea5421cc2af99d689e45 (MD5) Previous issue date: 2009 / Resumo: Estudos epidemiológicos têm demonstrado que o consumo de frutas e vegetais tem um efeito benéfico na redução da incidência de várias doenças como o câncer e doenças cardiovasculares. Esse efeito tem sido relacionado com a presença de compostos antioxidantes nesses alimentos, sobretudo os flavonóides. O tomate (Lycopersicum esculentum Mill.) é um dos vegetais mais consumidos no mundo, in natura ou processado, e também é rico em compostos antioxidantes como carotenóides, vitaminas e flavonóides. Os alimentos processados, frequentemente, são tidos como menos nutritivos que os alimentos in natura, devido, principalmente, ao fato de que alguns nutrientes são degradados pelas altas temperaturas empregadas. Assim, torna-se importante avaliar o efeito do processamento e da estocagem sobre os compostos antioxidantes do tomate e também sobre sua atividade antioxidante. Um planejamento experimental foi realizado para otimizar as condições de extração dos compostos fenólicos e concentração dos flavonóides em polpa de tomate concentrada. O método otimizado foi validado para as determinações de compostos fenólicos totais e flavonóides totais por espectrofotometria e também para a determinação de flavonóides por cromatografia líquida de alta eficiência (CLAE). Os métodos espectrofotométricos foram validados nos parâmetros repetibilidade e exatidão. A determinação de flavonóides por CLAE foi validada nos parâmetros seletividade, linearidade, precisão, exatidão e sensibilidade. O efeito do processamento e da estocagem sobre os compostos antioxidantes do tomate foi avaliado. Foram analisados os teores de compostos fenólicos totais, flavonóides totais, flavonóides por CLAE, ácido ascórbico, licopeno e ß-caroteno, bem como a atividade antioxidante das frações hidrofílicas e lipofílicas pelos métodos ABTS e DPPH. Verificou-se que, durante o processamento, em geral, não houve perdas dos compostos antioxidantes. Durante o armazenamento, observou-se grande degradação do ácido ascórbico, porém, os demais compostos mantiveram-se estáveis, e não foi observada nenhuma alteração na atividade antioxidante. O efeito do processamento sobre a atividade antioxidante do extrato fenólico foi também avaliado por espectroscopia de ressonância de elétron-spin (ESR) usando sal de Fremy e em sistema-modelo de lipossomas. Esses e os outros resultados de atividade antioxidante obtidos previamente foram correlacionados com os teores de compostos fenólicos totais a fim de melhor estudar os mecanismos de ação antioxidante envolvidos. A ação antioxidante das amostras de tomate, coletadas em diferentes etapas do processamento, foi testada em carne de frango processada sob alta pressão a 300, 600 e 800 MPa e armazenada sob refrigeração por 15 dias. A adição de 0,30% de subproduto (pele + semente) ou 0,10% de polpa concentrada resultou em uma fase lag de 6 dias para a formação de produtos secundários da oxidação lipídica na carne de frango processada a 600 MPa. O subproduto apresentou efeito similar também para a carne de frango processada a 800 MPa. O resultado deste trabalho mostrou que, embora o processamento e a estocagem de polpa de tomate possam ter degradado substâncias mais sensíveis como o ácido ascórbico, os demais compostos antioxidantes não sofreram alterações deletérias, e, para alguns, o processamento foi benéfico, aumentando sua disponibilidade. De forma semelhante, as atividades antioxidantes dos produtos processados foram iguais ou maiores que as das amostras in natura e se mantiveram estáveis durante o armazenamento por um ano. Além disso, o subproduto do processamento pode ter boas chances de aplicação como antioxidante em outros produtos alimentícios / Abstract: Epidemiological studies have shown that the consumption of fruits and vegetables has a beneficial effect on reducing some diseases like cancer and cardiovascular diseases. These benefits have been associated to the presence of antioxidant compounds in those foods, mainly flavonoids. Tomato (Lycopersicum esculentum Mill.) is one of the most worldwide consumed vegetables, in natura or processed. Moreover, tomato is rich in many antioxidant compounds like carotenoids, vitamins and flavonoids. Frequently, thermoprocessed foods are taken as less healthy than in natura foods, mainly because nutrient losses caused by high temperature. So, it is very important to evaluate the effect of processing and storage on tomato antioxidant compounds and on their antioxidant activity. A response surface methodology was used to optimize the phenolics extraction conditions and flavonoids concentration from concentrated tomato paste. The optimized method was validated for total phenolics and total flavonoids spectrophotometric determinations and also for flavonoids quantification by high performance liquid chromatography (HPLC). The spectrophotometric methods were validated for repeatability and recovery. Flavonoids determination by HPLC was validated for selectivity, linearity, precision, recovery and sensibility. Processing and storage effect on tomato antioxidant compounds was evaluated. Total phenolics, total flavonoids, flavonoids by HPLC, ascorbic acid, lycopene and ß-carotene were determined and also the antioxidant activity of hydrophilic and lipophilic fractions were studied using ABTS and DPPH methodologies. It was observed that during processing, in general, there was no loss of the antioxidant compounds present in tomato. During the storage time there was a great loss of ascorbic acid, but all other antioxidant compounds were stable and no changes in their antioxidant activity were observed. The effect of tomato paste processing on the antioxidant activity of phenolic extract was also analyzed through electron-spin resonance spectroscopy (ESR) using Fremy¿s salt, and in a liposome model-system. These and the other antioxidant activity results previously obtained were correlated with the total phenolics content found in the samples in order to better study the antioxidant mechanisms involved. The antioxidant action of tomato samples, collected at different processing steps, was analyzed during 15 days chill storage of high-pressure treated chicken meat balls at 300, 600, and 800 MPa. Addition of 0.30% tomato waste (skin + seeds) or of 0.10% final tomato paste to minced meat led to a lag phase of 6 days for formation of secondary oxidation products in meat treated at 600 MPa. The waste product seemed especially efficient in protecting chicken meat pressurized at 800 MPa, as a notably lower rate of formation of secondary oxidation products was found. This work showed that, although processing and storage of tomato paste might result in loss of the most labile substances like ascorbic acid, the other antioxidant compounds were not affected, and, for some of them, processing increased their availability. Similarly, the antioxidant activities of final products were equal to or greater than the in natura ones and remained unaltered during one year storage. In addition, waste material may have good chances of application as antioxidant in other foods / Doutorado / Ciência de Alimentos / Doutora em Ciência de Alimentos

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.

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.

As the most widely dispersed fauna around the world, insects are exposed to a range of stresses within their environments. Oxidative stress causes a disturbance of the balance between production of free radicals and antioxidant response, which leads to various physiological changes in an organism. Despite this, there are several of defense mechanisms, which include in particular the main antioxidant enzymes AKH. In this thesis, I tried to contribute especially to understand the physiological nature of telomere elongation after exposure to free radicals.

Antioxidants are widely used to protect organic materials from damages caused by autoxidation, an oxidation process that occurs under normal aerobic conditions. In this thesis, novel multifunctional organoselenium and organotellurium antioxidants were designed, synthesized, and evaluated in search for compounds with better radical-trapping capacity, regenerability, and hydroperoxide-decomposing ability. Selenium was incorporated into ebselenols and hydroxy-2,3-dihydrobenzo[b]selenophenes and tellurium into diaryl disulfides and aryltellurophenols. All newly developed antioxidants were evaluated in a chlorobenzene/water two-phase lipid peroxidation system containing suitable co-antioxidants in the aqueous phase. Ebselenol carrying a hydroxyl group (OH) ortho to selenium showed a two-fold longer inhibition time than the reference α-tocopherol in the presence of aqueous-phase ascorbic acid. 2,3-Dihydrobenzo[b]selenophenes carrying a 5- or 7-OH outperformed α-tocopherol both when it comes to radical-trapping capacity and regenerability. Alkyltellurothiophenols, in situ formed from their corresponding disulfides by tris(2-carboxyethyl)phosphine, were also efficient regenerable radical-trapping antioxidants. The consumption of N-acetylcysteine in the water phase was followed and found to be limiting for the duration of the inhibition. The hydroperoxide-decomposing ability of all organoselenium antioxidants was evaluated. Ebselenols were often better glutathione peroxidase mimics than the parent. In an effort to find out more about antioxidant mechanisms, aryltellurophenols carrying electron donating and electron withdrawing groups in the phenolic or aryltelluro parts were synthesized and OH bond dissociation enthalpies, BDEO-Hs, were calculated. Compounds carrying electron donating groups in the phenolic or aryltelluro part of the molecule showed the best radical-trapping capacity. Deuterium labelling experiments suggested that hydrogen atom transfer could be the rate-limiting step in the antioxidant mechanism.

Vitamin C är en populär ingrediens i hudvårdsprodukter, bland annat på grund av dess positiva effekter på kollagen-produktionen i huden och dess antioxidativa egenskaper. Dessvärre är vitamin C en känslig ingrediens som lätt bryts ned av ljus, syre, hög temperatur eller fel pH-värde. I dagsläget finns inga regleringar för kontroll av nedbrytning av aktiva ingredienser i kosmetiska produkter.  I den här studien har en metod utvecklats med omvänd-fas högupplösande vätskekromatografi (RP-HPLC) och detektor med ultraviolett (UV) ljus för att analysera halten C-vitamin i en kosmetisk testprodukt, hädanefter kallad OTP och en modifierad variant av denna, kallad MTP. En stabilitetstudie gjordes vid olika temperaturer och ljusförhållanden på dessa produkter. En jämförelse gjordes även mellan en högre och lägre syretillgång. I metoden som valdes för stabilitetsanalys använde UV-detektor (254 nm). Den kromatografiska kolonnen innehöll C-18-stationärfasoch hade en längd om - 250x4.6 mm, med 5 µm partikelstorlek, från Chrompack. Mobilfasen bestod av 20 mM lösning av ättiksyra i Milli Q-vatten och metanol i förhållandet 95:5 (v/v) och mobilfashastigheten 2 ml/min, vilket gav en retentionstid på ca 2.4 min för vitamin C. I MTP bröts vitamin C ned snabbare än i OTP. Den lägsta nedbrytningshastigheten kunde ses vid den lägsta temperaturen (4℃) och den lägre syretillgången av dem som studerades. Ett linjärt samband kunde ses mellan förvaringstiden och koncentrationen av vitamin C som fanns kvar i produkten vid detta förvaringsförhållande. / Vitamin C is a popular ingredient in skin care products, due to its positive effect on the collagen production and its antioxidative characteristics. Unfortunately, vitamin C is a sensitive ingredient that is easily degraded by light, oxygen, elevated temperatures, or the wrong pH-value. To today’s date, there are no regulations controlling the degradation of active ingredients in cosmetic products.  In this study, a method has been developed for Reversed Phase-Liquid Chromatography (RP-HPLC) and Ultra Violet (UV)-light detector to analyze the vitamin C content in a cosmetic test product, in this study called OTP and a modified variant of the same product, called MTP. A stability study was made at different temperatures and light conditions. A comparison was also made between higher or lower levels of oxygen present. The method chosen was performed at a wavelength of 254 nm. The column used contained a C-18 stationary phase (250x4.6 mm, 5 µm particle size) from Crompack. The mobile phase consisted of 20mM solution of acetic acid in Milli Q water and methanol 95:5 (v/v) and the flow rate was set to 2 ml/min, which gave a retention time of approximately 2.4 min for vitamin C. Vitamin C was degraded faster in MTP than in OTP. The lowest degradation rate was found at the lowest temperature (4℃) and the lower oxygen content among the ones studied. A linear relationship was found between storage time and the vitamin C concentration left in the product at this storage condition.

All-trans-retinol (vitamin A) används ofta som en aktiv ingrediens i kosmetiska produkter på grund av dess kliniskt validerade anti-age-egenskaper. Däremot är användningen av all-trans-retinol i kosmetiska formuleringar begränsad till följd av den kemiska stabiliteten av all-trans-retinol som påverkas av värme, syre, ljus och syror. Både kompositionen av en kosmetisk formulering, samt lagringsförhållanden och förpackningen av produkten, kan påverka nedbrytningen av all-trans-retinol till mindre aktiva former.  I denna studie har stabilitetstestning genomförts under två månader i syfte att utvärdera inverkan som lagringstemperatur (21°C och 5°C) och produktförpackning (en luftfri behållare och en burk) kan ha på nedbrytningen av all-trans-retinol i en experimentell oljegel. All-trans-retinol extraherades med metanol innehållande 0.5 mg/mL butylhydroxytoluen (BHT) och analyserades med reversed-phase HPLC med 1% ammoniumacetat och metanol (12:88, v/v) som mobilfas. I HPLC-kromatogrammen upptäcktes en okänd nedbrytningsprodukt, vilket möjliggjorde stabilitetstestning av all-trans¬-retinol genom att undersöka förändringar i förhållandet mellan nedbrytningsprodukten och all-trans-retinol. Stabilitetstestningen av de experimentella oljegelerna resulterade i mindre än 4% nedbrytningsprodukt i förhållande till mängden all-trans-retinol efter 56 dagars lagring, oberoende av produktförpackning och lagringstemperatur, med den förslagna analysmetoden. Studien visade också att instabiliteten hos extraherad all-trans-retinol har en dominerande inverkan på resultaten som kan leda till en överskattning av nedbrytningsprodukten på grund av temperaturen under beredning och lagring av förberedda prover. Dessutom utvärderades stabiliteten av all-trans-retinol i metanol och metanol innehållande 0,5 mg/ml butylhydroxytoluen (BHT). Upp till 6% nedbrytning av all-trans-retinol i metanol med BHT kan förväntas om beredda proverna lagras i rumstemperatur, medan mindre än 1% nedbrytningsprodukt detekterades i prover som bevaras kylda under analysen. Av denna anledning har det föreslagits att förhållandena vid beredning, hantering och lagring av extraherad all-trans-retinol bör kontrolleras för att förhindra inverkan från omgivningen, såsom temperatur, ljus och syre. / All-trans-retinol, or vitamin A, is frequently used as an active ingredient in cosmetic products because of its clinically validated anti-aging properties. The use of all-trans-retinol in cosmetic formulations is limited by its susceptibility to heat, oxygen, light, and acids. In a cosmetic product, the composition, as well as the storage conditions and the type of packaging, may influence the degradation of all-trans-retinol into less active forms.  In this study, long-term stability testing was conducted with the purpose to evaluate the effect that storage temperature (21°C and 5°C) and product packaging (an airless container and a jar) may have on the degradation of all-trans-retinol in an experimental oil-gel during a 2-months period. All-trans-retinol was extracted with methanol containing 0.5 mg/mL butylhydroxytoluene (BHT) and was analysed with a reversed-phase HPLC system, using 1% ammonium acetate and methanol (12:88) as the solvent system. The HPLC chromatograms revealed an unknown degradation product, allowing stability testing of all-trans-retinol by detecting variations in the ratio between the degradation product and all-trans-retinol. The stability testing of the experimental oil-gels resulted in less than 4% degradation product in relation to all-trans-retinol after 56 days of storage, independent of the product packaging and storage temperature, with the proposed analytical method. It was also shown that the instability of extracted all-trans-retinol will have a predominant impact on the results causing an overestimation of the degradation product because of the temperature during sample preparation and storage. In addition, the stability of all-trans-retinol in methanol and methanol containing 0.5 mg/mL butylhydroxytoluene (BHT) was evaluated. It was concluded that up to 6% degradation of all-trans-retinol in methanol with BHT can be expected if prepared samples are stored in room temperature, while less than 1% degradation product will be present if prepared samples are kept cold during analysis. It has been proposed that the conditions during preparation, handling, and storage of extracted all-trans-retinol should be controlled to prevent interference of external conditions, such as temperature, light, and oxygen.

<p>Numerous diseases are associated with reduced antioxidant defence and oxidative stress. The antioxidant defence includes dietary and endogenous antioxidants and involves complex interactions between them. The effects of dietary factors on antioxidant status and oxidative stress of healthy humans were investigated in the studies described in this thesis. Assays of plasma antioxidant capacity encompass interactions between various antioxidants. Although uric acid has an unclear function as an antioxidant, it is a major determinant of antioxidant capacity. We measured antioxidant capacity in the presence and absence of uric acid to provide more information on the application of measures of antioxidant capacity. Individuals with high dietary intakes of various antioxidants and antioxidant rich foods, especially when combined, had higher plasma antioxidant capacities than those with lower antioxidant intakes. However, there were no associations between dietary intake of antioxidants or antioxidant rich foods and the plasma concentration of F₂-isoprostanes, which is considered a reliable biomarker for oxidative stress. Intakes of various doses of a mixture of bilberry juice and black tea, rich in flavonoids for four weeks, increased antioxidant capacity in some groups, but urine levels of F₂-isoprostanes were not affected. There were substantial individual variations in responses to the drinks related to baseline antioxidant capacity. Supplementation with eicosapentaenoic acid and docosahexaenoic acid decreased the plasma levels of F₂-isoprostanes, but not prostaglandin F_2α formation or antioxidant capacity. </p><p>It was concluded that a high intake of foods rich in antioxidants is related to improved antioxidant status. After intake of foods rich in antioxidants, the antioxidant status may increase, but with considerable individual variation in the responses, which warrants further investigation. Lipid peroxidation <i>in vivo</i> is not easily affected by dietary antioxidants in healthy humans. Although n-3 fatty acids are highly unsaturated, they reduce nonenzymatic free radical-catalyzed lipid peroxidation, but not enzymatic lipid peroxidation.</p>