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Lipase-catalyzed synthesis of selected phenolic lipids in organic solvent mediaSabally, Kebba. January 2006 (has links)
No description available.
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Lipase-catalyzed synthesis of selected phenolic lipids in organic solvent mediaSabally, Kebba. January 2006 (has links)
Lipase-catalyzed esterification and transesterification reactions of selected phenolic acids with lipids were investigated in organic solvent media. The esterification of linoleyl alcohol with dihydrocaffeic acid (DHA) in neat hexane medium resulted in highest esterification yield (EY) of 17% when a Candida antarctica lipase (Novozym 435) was used to catalyze the reaction. The use of co-solvents t-butanol and 2-butanone with hexane resulted in a dramatic increase in EY. The highest EY of 83% was obtained in hexane:2-butanone mixture of 85:15 (v/v) using Novozym 435; however lower EY (40%) was obtained when a lipase from Rhizomucor meihei (Lipozyme IM 20) was used. Increasing the amount of the co-solvent 2-butanone in the hexane:2-butanone mixture to 75:25 (v/v) resulted in a lower EY of 75% with Novozym 435; using the same enzyme, the esterification of a more unsaturated alcohol, linolenyl alcohol, with DHCA in the hexane:2-butanone mixture of 75:25 (v/v) resulted in EY of 76% which was similar to that obtained with linoleyl alcohol as lipid substrate. The esterification of DHCA and ferulic acid with linolenyl alcohol in the hexane:2-butanone mixture of 65:35 (v/v) resulted in an EY of 58 and 16%, respectively. Both linoleyl and linolenyl alcohols demonstrated mass action effects with EY of 99% in DHCA: fatty alcohol ratio of 1:8. Using a molar ratio of 1:2, the transesterification reactions of DHCA with trilinolein (TLA) and trilinolenin (TLNA) in hexane:2-butanone mixture of 75:25 (v/v) resulted in total transesterification yields (TYs) of phenolic lipids of 66 and 62%, respectively. The TYs of phenolic monoacylglycerols was higher than that of phenolic diacylglycerols for both TLA and TLNA transesterification reactions. A lower molar ratio of DHCA to TLA of 1:4 resulted in a lower TY of 53%. Using a molar ratio of 1:2, the TY of TLA and TLNA with ferulic acid in hexane:2-butanone mixture of 65:35 (v/v) was 16 and 14%, respectively. An equal molar transesterification reaction of DHCA with flaxseed oil, in a hexane:2-butanone mixture of 75:25 (v/v), resulted in the production of only phenolic monoacylglycerols (19%); however, decreasing the molar ratio resulted in the production of both phenolic mono and diacylglycerols. A molar ratio of DHCA to flaxseed oil (1:8) resulted in a TY of 76%, with 43 and 33% phenolic mono and diacylglycerols, respectively. Changing the solvent mixture of hexane:2-butanone from 65:35 to 85:15 (v/v) resulted in an increased in the TY of phenolic diacylglycerols from 24 to 55% with no significant effect on the TY of phenolic monoacylglycerols. The transesterification reaction resulted in a change in the composition of the C18:3 FA from 53% in the unmodified oil to 60 and 65% in the phenolic mono and diacylglycerols. Transesterification reaction of DHCA with fish liver oil in the solvent mixtures of hexane:2-butanone of 75:25 and 85:15 (v/v) resulted in TY of 56 and 65%, respectively. Transesterification in solvent: mixture of 75:25 resulted in a 40 and 16% TY of phenolic mono and diacylglycerols, respectively, whereas that in the solvent mixture of 85:15 (v/v) resulted in a 38 and 37% TY of phenolic mono and diacylglycerols, respectively. The structures of phenolic lipids of linoleyl and linolenyl alcohols with DHCA were confirmed by LC/MS analysis likewise for the phenolic mono and diacylglycerols from transesterification of DHCA with TLA and TLNA as well as flaxseed and fish liver oils. The phenolic esters of the fatty alcohols demonstrated radical scavenging properties similar to that of alpha-tocopherol but less than for DHCA; however, the phenolic lipids obtained with the use of TLA and TLNA as substrate as well as flaxseed and fish liver oil, demonstrated significant radical scavenging effects but less than that of alpha-tocopherol and DHCA.
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Replacement of dietary fish oil with vegetable oils : effects on fish healthGood, Joanne Elizabeth January 2004 (has links)
The work presented in this thesis examined the effects of dietary fish oil replacement on fish innate and adaptive immune function, disease resistance tissue histopathology and fatty acid composition of lipids in peripheral blood leukocytes. Dietary trials with Atlantic salmon (Salmo salar), Sea bass (Dicentrarchus labrax), Atlantic cod (Gadus morhua) and Arctic char (Salvelinus alpinus) were conducted in which fish oil was replaced by rapeseed oil, linseed oil, olive oil, palm oil, echium oil or a mixture of these oils. A significant reduction in respiratory burst activity was most pronounced in salmon and sea bass fed high levels of rapeseed oil-containing diets. In addition, rapeseed and olive oil inclusion in the diets of salmon and sea bass significantly reduced the head kidney macrophage phagocytic capacity to engulf yeast particles. A reduction in prostaglandin E2 levels was found to be related to a reduction in macrophage respiratory burst activity in salmon fed linseed oil diets and sea bass fed a dietary blend of linseed, palm and rapeseed oils. Changes in macrophage function may be a contributing factor causing a reduction in serum lysozyme activity observed in some trials. No significant differences were detected in cumulative mortality of Atlantic salmon fed an equal blend of linseed and rapeseed oils challenged with Aeromonas salmonicida. However, resistance to Vibrio anguillarium was significantly impaired in Atlantic salmon fed a blended oil diet containing linseed, rapeseed and palm oil. The major histological difference of fish fed vegetable oil diets was the accumulation of lipid droplets in their livers. Dietary fatty acid composition significantly affected the fatty acid composition of peripheral blood leukocytes. Generally, fish fed vegetable oil diets had increased levels of oleic acid, linoleic acid and a-linolenic acid and decreased levels of eicosapentaenoic acid, docosahexaenoic acid and a lower n-3/n-6 ratio than fish fed a FO diet. In conclusion, the results from these studies suggest that farmed fish species can be cultured on diets containing vegetable oils as the added oil source. However, feeding high levels of some vegetable oils may significantly alter some immune responses in the fish, especially head kidney macrophage function, disease resistance and, in addition, may cause an increase in tissue histopathology.
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Effects of dietary selenium and fish oil (MaxEPA) on arachidonic acid metabolism and hemostatic function in the ratSong, Jihyun 12 October 1989 (has links)
The purpose of this study was to investigate whether
the beneficial effects which the consumption of fish oil
imparts on hemostatic function can be modified by the level
of dietary selenium. Male Sprague Dawley rats were fed for
eight weeks semipurified diets containing 7% corn oil (by
weight) or 5.5% fish oil (MaxEPA) plus 1.5% corn oil with or
without selenium supplementation.
The indicators of selenium status (glutathione
peroxidase activity and selenium level) were significantly
lower in the rats given inadequate selenium, regardless of
the type of fat fed. In the animals fed adequate selenium,
these same indicators tended to be lower when fish oil was
fed. Although feeding of fish oil increased hepatic and
aortic malondialdehyde (MDA), selenium supplementation
decreased its level in the liver.
Selenium deficiency led to a decrease in the relative
weight percent of 22:6 n-3 in aorta and plasma. Increases in the levels of 20:5 n-3, 22:5 n-3, 22:6 n-3, 20:3 n-6 and
a decrease in the level of 20:4 n-6 were observed in plasma
total lipids and aortic and hepatic phospholipids when fish
oil was fed. The increased level of 20:3 n-6 suggests that
delta 5-desaturase activity was decreased by fish oil
feeding.
The level of aortic 6-keto-prostaglandin F₁alpha (6-
keto-PGF₁alpha) was highest in the rats fed diets that
contained corn oil but no selenium supplementation; selenium
supplementation, however, eliminated the difference in the
level of 6-keto-PGF₁alpha between fish oil and corn oil fed
groups. The levels of thromboxane B₂ (TXB₂) and ADP-induced
platelet aggregation were decreased significantly by fish
oil feeding and tended to be lower with selenium
supplementation. Selenium supplementation did not increase
bleeding time while fish oil feeding did.
These data indicate that selenium supplementation may
decrease fish oil induced lipid peroxidation in liver: this
is reflected in the lower hepatic MDA levels in the fish oil
fed animals with selenium supplementation and the increased
22:6 n-3 levels in aorta and plasma. Selenium deficiency
led to an increase in the level of 6-keto-PGF₁alpha in the
rats fed corn oil. Its effects on TXB₂ level and ADP-induced
platelet aggregation are marginal. Overall the
beneficial effect of selenium supplementation on hemostatic
function appears weaker than that of fish oil feeding. / Graduation date: 1990
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Proteomics study of the effects of fish oil and corn oil enriched diet on membranous nephritisYe, Yisha. January 2008 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2008. / Includes bibliographical references (leaf 131-149) Also available in print.
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Study of seal oil in reducing the nephrotoxicity of cyclosporine A /Yang, Wei, January 2003 (has links)
Thesis (M.Sc.)--Memorial University of Newfoundland, 2004. / Bibliography: leaves 147-168.
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The effect of seal oil on paclitaxel induced cytotoxicity and apoptosis in breast carcinoma MCF-7 and MDA-231 cell lines /Wang, Zheyu, January 2004 (has links)
Thesis (M.Sc.)--Memorial University of Newfoundland, 2005. / Bibliography: leaves 128-138.
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Organohalogen environmental pollutants in Baltic fish : chemical characterization and toxicological evaluation with a focus on bone disturbances /Stern, Natalia, January 2005 (has links)
Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 4 uppsatser.
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Stability of catfish methyl esters under normal versus accelerated storage conditionsJongrattananon, Saowalee, January 2008 (has links)
Thesis (M.S.)--Mississippi State University. Department of Food Science, Nutrition, and Health Promotion. / Title from title screen. Includes bibliographical references.
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A case study of factors impacting on marketing of South African fish oil in the animal feed marketStefanus, Titania Vaida January 2002 (has links)
Thesis (MTech (Business Administration))--Peninsula Technikon, Cape Town, 2002 / The growing and declining demand of the
different fish oil application markets.
The price of heavy furnace oil compared to fish oil selling price. (Heavy furnace oil is used
to generate energy) .
The research also investigated the impact of low price
fish oil substitutes on the South African fish oil
producers. The most important substitute in the current
South African majority market, the animal feed market, is
vegetable oils. The research finding is that the South
African fish oil producers must follow the vegetable oil
selling price trend.
The most important finding of the research is the high priority the fish oil quality achieves in all the fish oil market segments. The South African domestic market is limited in that it is only the animal feed market and
the refinery.
export market.
The alternative market to sell to is the
However, the international fish oil
market perceives the South African fish oil to be of low
quality. A mindset regarding the importance of fish oil
quality has to start at the South African fish oil producers. It is vital that the South African fish oil producers institute quality systems to improve their fish
oil quality. The South African fish oil producers must gear themselves to become globally competitive.
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