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In this report we describe the development of a method for the concurrent reversed-phase high-performance liquid chromatographic separation and photodiode array detection of human plasma retinol, tocopherols and carotenes. For a single sample injection, retinol, retinyl acetate, α- tocopherol, γ-tocopherol, α-tocopheryl acetate, all-trans-α-carotene and all-trans-β-carotene, as well as the mono-cis geometrical isomers of β- carotene were separated and detected. Analytical separations were performed at a subambient temperature (0°C) over a Suplex pKb-100 reversed-phase analytical column with an isocratic mobile phase of methanol-methyl tert.- butyl ether-water (80:20:5, v/v/v) at a flow-rate of 0.8 ml/min for 60 min. Standards and samples were reconstituted in ethanol, and typically, 50 μl was injected for analysis. By HPLC, compounds of interest were clearly resolved and detectable at the picomole level.

Thesis (M.S.)--Pennsylvania State University, 1972. / Includes bibliographical references.

Colorectal cancer is the second most common cause of cancer deaths in the United States. Vitamin E (VE) and other antioxidants may help prevent colon cancer by decreasing the formation of mutagens arising from the free radical oxidation of fecal lipids or by "non-antioxidant" mechanisms. VE is not a single molecule, but refers to at least eight different molecules, that is, four tocopherols and four tocotrienols. Methods: Both animal models and human colon cancer cell lines were used to evaluate the chemopreventive potential of different forms of VE. Rats were fed diets deficient in tocopherols or supplemented with either α-tocopherol or γ-tocopherol. Half the rats in each of these groups received normal levels of dietary Fe and the other half Fe at eight times the normal level. In our cell experiments, we looked at the role of γ-tocopherol in upregulating peroxisome proliferator-activated receptor-γ (PPAR-γ) in the SW 480 human cell line. Results: Rats fed the diets supplemented with α-tocopherol had higher levels of VE in feces, colonocytes, plasma, and liver than did rats fed diets supplemented with γ-tocopherol. Dietary Fe levels did not influence tocopherol levels in plasma, liver, or feces. For colonocytes, high dietary Fe decreased tocopherol levels. Rats fed the γ-tocopherol-supplemented diets had lower levels of fecal lipid hydroperoxides than rats fed the α-tocopherol-supplemented diets. Ras-p21 levels were significantly lower in rats fed the γ-tocopherol-supplemented diets compared with rats fed the α-tocopherol-supplemented diets. High levels of dietary Fe were found to promote oxidative stress in feces and colonocytes. Our data with the SW480 cells suggest that both α- and γ-tocopherol upregulate PPAR-γ mRNA and protein expression, γ-tocopherol was, however, found to be a better enhancer of PPAR-γ expression than α-tocopherol at the concentrations tested.

No description available.

The minimal refining method described in this study made it possible to neutralize crude canola oil using some weaker alkali such as Ca(OH)2, MgO and Na2siO3 as an alternative for NaOH. After citric acid degumming, more than 98% of phosphorous content was removed from crude oil. The free fatty acid content after minimal neutralization with calcium hydroxide decreased from 0.50 to 0.03%. Other quality parameters such as peroxide value, anisidine value and chlorophyll content were within commercially acceptable levels. The use of Trisyl silica and Magnesol R60 made it possible to remove the hot water washing step and to decrease the amount of remaining soap to less than 10 ppm. There was no significant change in chemical characteristics of canola oil after wet and dry bleaching. During traditional neutralization, total tocopherol loss was 19.6% while minimal refining with Ca(OH)2, MgO and Na2siO3 resulted in 7.0, 2.6 and 0.9 % reduction in total tocopherols. Traditional refining removed 23.6% of total free sterols, although after minimal refining free sterols content did not change significantly (p<0.05). Both traditional and minimal refining resulted in almost complete removal of polyphenols from canola oil. Total phytosterols and tocopherols in two cold press canola oils were 7700, 8400 mg/kg and 370, 350 mg/kg, respectively. Total phytosterols and tocopherols contents in solvent extracted canola oil were 9500, 500 mg/kg, respectively. The minimal refining method described in this study was a new practical approach to remove undesirable components from crude canola oil confirmed with commercial refining standards as well as preserving more healthy minor components. / This research project is supported by National Services and Engineering Research Council of Canada (NSERC).

Orientador: Helena Teixeira Godoy / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-08T02:47:43Z (GMT). No. of bitstreams: 1 Costa_PauloAfonsoDa_D.pdf: 23936384 bytes, checksum: a6d6688127d488f15b73823f62bef97d (MD5) Previous issue date: 2007 / Doutorado / Doutor em Ciência de Alimentos

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2002. / Härtill 4 uppsatser.