Diet-derived polyphenols are believed to have health benefits on account of their antioxidant properties. Cardiovascular health is considered to be a suitable target for antioxidant therapy because oxidative stress is implicit in atherogenesis – the disease process that underpins heart attacks, ischaemic strokes and peripheral vascular disease. Numerous in vitro, in vivo and clinical studies indicate that polyphenols are protective in cardiovascular disease, but their mechanism of action still remains ambiguous. This thesis describes a wide range of studies to characterise the activity and stability of a key polyphenol, delphinidin, found in widely consumed berries, and ultimately to test the hypothesis that delphinidin, at physiologically relevant concentrations (~1 µM), protects cultured human umbilical vein endothelial cells (HUVECs) against oxidative damage via a mechanism that is independent of direct antioxidant activity. Delphinidin aglycone was found to be unstable in tissue culture medium, in which it decomposed rapidly to simple phenolic compounds, including gallic acid. Electron paramagnetic resonance spectroscopy indicated that, if anything, both delphinidin and gallic acid were pro-oxidant rather than antioxidant. Moreover, high concentrations of both delphinidin and gallic acid induced rapid morphological changes in HUVECs, most notably in the formation of vacuoles or vesicles. Treatment of HUVECs with a range of concentrations (1 nM - 100 µM) of delphinidin and gallic acid showed that high (100 µM) concentrations of both were cytotoxic. However, both agents were found to have a protective effect in cells exposed to oxidative stress when present at concentrations of ~1 µM – too low to be due to direct antioxidant activity. Deeper examination of cells treated with delphinidin and gallic acid indicated that the protective effect was perhaps partially mediated by changes in expression of the intracellular antioxidant, glutathione. Taken together, the results in this thesis suggest that metabolic products of delphinidin might be responsible for the antioxidant effects seen on account of initiating cellular defence responses.

Anthocyanins have been shown to possess specific antioxidant capacities, which may provide an underlying protective effect against many chronic diseases . Although the antioxidant capacity of anthocyanins has been well established, less is known about the extent to which specific anthocyanin composition affects total antioxidant capacity . The aim of the present study was to compare the antioxidant capacity of two different soft fruits, blackcurrant and grape, which have distinctly different anthocyanin profiles. The anthocyanin profiles of grape and blackcurrant were characterized by HPLC/MS coupled with a diode array detector. Results showed that blackcurrant contained four predominant anthocyanins, cyanidin 3-glucoside, delphinidin 3-glucoside, cyanidin 3-rutinoside, and delphinidin 3-rutinoside . In contrast, malvidin 3-glucoside, delphinidin 3-glucoside, cyanidin 3-glucoside, petunidin 3-glucoside, and peonidin 3- glucoside were the major anthocyanins found in grape . The concentration of individual anthocyanins in all berries was quantified with HPLC/UV using cyanidin 3-glucoside as an external standard . Finally, results showed a greater (p<0.05) antioxidant capacity of blackcurrant compared to grape. The total antioxidant capacity of crude extracts from each was measured by Oxygen Radical Absorbance Capacity (ORAC) and ABTS assays. Anthocyanin antioxidant capacity index (AACI), derived from the product of antioxidant (ORAC) activity for each of major anthocyanin present in blackcurrant and grape, was also used to determine whether the antioxidant capacity of crude anthocyanin fractions represents either the sum total anthocyanin content or, alternatively, a synergy between different anthocyanins components . Our results indicated that a plausible potential synergy between anthocyanin components in regards to ORAC antioxidant capacity existed in blackcurrant and grape semi-purified anthocyanin extracts. Furthermore, it could be concluded that both total anthocyanin content as well as the composition of individual anthocyanins in soft fruits is important to assess total antioxidant capacity of different berry sources . / Land and Food Systems, Faculty of / Graduate

Elderberry is a traditional herb which has always been used in folk medicine. The berries contain many biologically active compounds, from which antocyanins are the most important. The fruits also contain flavonoids, organic acids, suggars, cyanogenic glycosides and another compounds such as vitamins, tannins, amino acids, potassium, calcium and phosphorus. The berries are used in food industry for production of marmelade, fruit syrups, wine and another delicacies. The drug Sambuci fructus is currently a subject of interest in pharmacy and medicine. The research examines the beneficial effects of antocyanins on human health and the possible use of antocyanins in medicine and pharmacy. Antocyanins exhibit a strong antioxidant activity, which can potentially be used for treating cardiovascular, tumor or metabolic disorders. The possibility of using the antioxidant effects in treatment for example hyperlipidemia, obesity and metabolic disorder is investigated. The listed effects can be also important as protection against oxidative damage of cells in diabetes mellitus. The antiinflammatory and antiinfective action is also important, it was investigated for both viral and antibacterial infections. At the same time it was shown, that elderberry could act as an effective immunostimulant. The ability of...

Even though early man did not know the nature of coloring matter in flowers, he used the coloring matter as dye for centuries. There are a variety of reasons for the interest of chemists in natural and artificial coloring matters. One of these is the color pleasure, anothe1· is the commercial importance. The visible color facilitates the experimental work in the search for methods if separation, purification and determination of organic structures. Search for the knowledge of coloring matter goes far back in history. Man has dyed his textiles with the help of mordants from the most ancient times up to the time of Perkin's discovery of mauve. Then a new era in dyestuff chemistry commenced. In the first half of the nineteenth century with the rise and development of the study of Organic chemistry much attention was directed to the extraction and characterization of pure coloring matters from natural sources .... usually the bark, leaves, fruits. or sap of trees or plants. During the twentieth century -- and just a little before that--great progress has been made in the synthesis of many typical natural coloring matters and the improved technique and novel synthetical methods which will bear upon the general progress of chemistry. This research was done with the purpose of isolating and identifying the coloring matter in the flowers of Vinca Major, with the common name of periwinkle. This was done by extracting the pigment of the flowers with methanol, amyl alcohol, and crystallizing the pigment as a chloride. For this pigment, solubility, color reactions, spectra and other physical properties were obtained.

In this investigation, the basic pigment component, or anthocyanidin, of the ten most common spots was identified using paper and thin layer chromatographic techniques.

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Inhibition of blueberry PPO activity by sodium benzoate, potassium sorbate and potassium metabisulfite and their influence on degradation of individual anthocyanins in an extract was studied. Maceration of blueberries was carried out at 55ºC for 1h with the addition of 0.1% sodium benzoate or with blanching pretreatment at 90ºC for 1min. After maceration pretreatments the extracted juice was processed with traditional hot fill pasteurization, high hydrostatic pressure (HHP) and pulsed electric field (PEF). Sodium benzoate and potassium metabisulfite were very effective PPO inhibitors in concentrations of 0.1% and 10ppm, respectively. Potassium sorbate was the weakest inhibitor, with 50% PPO remaining. Degradation of anthocyanins by PPO was dependent on their structure. Tri-phenolic anthocyanins experienced the most degradation, followed by diphenolic and monophenolic compounds, respectively. Sodium benzoate was the most effective at preventing anthocyanin degradation; potassium metabisulfite did not have any protective effect, while potassium sorbate increased anthocyanin degradation Blanching of blueberries inactivated native PPO, but also increased the degradation of anthocyanins, especially malvidin glycosides. Addition of 0.1% sodium benzoate decreased PPO activity when compared to frozen blueberries but not in respect to control maceration. Only 12% of anthocyanins and 33-41% of phenolics were extracted into juice from the frozen fruit. Hot fill pasteurization, high hydrostatic pressure and pulsed electric field did not significantly influence anthocyanins, phenolics and antioxidant activity in blueberry juice.

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