Plasmalogens have been reported to possess antioxidant activity; a paradoxical finding given that plasmalogens often comprise highly oxidizable polyunsaturated fatty acids esterified to the central position of the glycerol backbone. However a reasonable mechanism accounting for plasmenyl lipid activity has yet to be advanced, despite the fact that other monounsaturated lipids including cholesterol and oleate have been extensively studied. Plasmenylcholine was synthesized de novo to resolve its antioxidant activity as well as to carry out mechanistic studies to understand its basis. Autoxidation of a vinyl ether model substrate yielded a kp of 6 M-1 s-1, which affirmed it was as slower than cholesterol. However, corresponding experiments with a deuterated substrate yielded a value of 89 M-1 s-1, questioning the reliability of these studies. Our studies of plasmenyl lipid peroxidation inspired us to look into the mechanism of autoxidation of the monounsaturated lipid, oleate (using LC-MS/MS with APCI+), which was reported to proceed exclusively via H-atom transfer (HAT). Herein we have shown for the first time that oleate epoxides are formed in the autoxidation of the monounsaturated lipid.

No description available.

No description available.

The adsorption of oleate at the goethite-water interface has been studied. In addition, the interactions of oleate at other mineral-water interfaces were considered. / Mainly by means of a literature review, a bulk equilibrium solubility diagram for oleic acid in water was constructed, as a function of total oleate concentration and pH. The competing bulk precipitation equilibria for oleic acid mineral phases such as iron (III) oxides, barite, calcite and fluorite and the relevant metal oleates, were considered graphically. Literature, adsorption, flotation recovery, electrokinetic and infrared work was examined in the light of this bulk precipitation data. It was found that many of these studies have been carried out in pH-concentration regions where bulk equilibrium phase changes were occurring, such as precipitation of oleic acid or of metal oleates. Adsorption behaviour in these systems was obscured by the bulk precipitation effects. / Adsorption experiments were carried out with oleate in the presence of goethite, choosing pH and concentration such that bulk precipitation effects were not important. Electrostatic and hydrophobic interactions as well as chemisorption, appeared to be of importance in the adsorption process. / A new approach for surfactant adsorption, a multiple equilibrium model, was suggested to describe quantitatively, the adsorption of oleate at the goethite-water interface. This approach considers oleic acid solution equilibria. The adsorption process is represented by the reaction of neutral goethite surface sites with oleate and protons in the manner of solution equilibria. A good fit was obtained to the experimental data. The model predicts that the acid-soap species HOI2 is the most important adsorbed species.

Plasma membranes have a structural property, commonly referred to as membrane fluidity, that is compositionally regulated. The two main features of plasma membrane lipid composition that determine membrane fluidity are the ratio of cholesterol to phospholipids and the ratio of saturated to unsaturated fatty acids that are incorporated into the phospholipids. These ratios are determined, at least in part, by regulation of membrane lipid biosynthesis-particularly that of cholesterol and oleate. It now appears that cholesterol and oleate biosynthesis are feedback regulated by a common transcriptional mechanism which is governed by the maturation of the SREBP transcription factors. In this article, we briefly review our current understanding of transcriptional regulation of plasma membrane lipid biosynthesis by sterols and oleate. We also discuss studies related to the mechanism by which the physical state of membrane lipids signals the transcriptional regulatory machinery to control the rates of synthesis of these structural components of the lipid bilayer.

No description available.

La relation entre l’obésité et le cancer, bien qu’établie par des études épidémiologiques, est peu connue. Pourtant, environ 25 % des cancers pourraient y être attribuables. Parmi les cancers reliés à l’obésité, les cancers du côlon, du sein chez les femmes ménopausées et de la prostate sont les plus fréquents. Des études sur modèles animaux ont suggéré une association positive entre une diète riche en gras et le développement du cancer mammaire et de la prostate. Nous avons étudié les mécanismes moléculaires par lesquels les acides gras influencent le devenir de lignées de cellules cancéreuses du sein et de la prostate. Ces travaux ont montré que les acides gras insaturés, dont l’oléate, induisent la prolifération cellulaire tandis que les acides gras saturés, dont le palmitate, diminuent la prolifération. Un traitement à l’oléate stimule la formation de gouttelettes lipidiques dans le cytoplasme des cellules de cancer du sein MDA-MB-231 et de la prostate DU145 alors qu’un traitement au palmitate entraîne l’apoptose. Le mécanisme d’action de l’oléate sur la prolifération a été étudié de façon plus approfondie. L’utilisation d’inhibiteurs pharmacologiques nous a permis de déterminer que l’effet prolifératif de l’oléate implique la voie PI3K/Akt, la voie ERK1/2 et l’activation d’un ou de plusieurs récepteur(s) couplé(s) aux protéines G (GPCR). L’oléate induit la phosphorylation rapide des protéines Akt et ERK1/2 dans les cellules de cancer du sein MDA-MB-231 et de la prostate DU145. Au cours des dernières années, deux GPCRs ont été identifiés comme étant activables par des acides gras à moyennes et à longues chaînes, GPR40 et GPR120. GPR40 étant exprimé dans plusieurs lignées cellulaires de cancer du sein et de la prostate contrairement à l’expression de GPR120 qui était inexistante dans la plupart des lignées, nous avons étudié l’implication de GPR40 dans l’effet prolifératif de l’oléate. Ces deux récepteurs n’étant pas exprimés dans les cellules épithéliales mammaires humaines en culture primaire, ces cellules ne répondent pas aux effets de l’oléate sur la prolifération et l’activation des voies de signalisation. L’activation des voies Akt et ERK1/2 par l’oléate dans les cellules MDA-MB-231 et DU145 est potentialisée par la surexpression du récepteur GPR40 et inhibée par l’utilisation d’un siRNA dirigé contre ce récepteur. Cependant, la prolifération induite par l’oléate ne semble pas affectée par la présence d’un siRNA dirigé contre GPR40. L’oléate étant un acide gras, il est capable d’entrer librement dans les cellules et une partie de ses effets sur la prolifération pourrait être attribuée à sa métabolisation. Un agoniste de GPR40, le GW9508, est en mesure d’activer GPR40 sans toutefois entrer dans les cellules ni activer le métabolisme de l’oléate. Le GW9508 stimule la phosphorylation des protéines Akt et ERK1/2 dans les cellules du cancer du sein MDA-MB-231 et de la prostate DU145, mais il n’est pas en mesure d’induire la prolifération cellulaire comme le fait l’oléate. Ces résultats nous permettent de mieux comprendre le mécanisme d’action de l’oléate sur les cellules de cancer du sein et de la prostate. L’oléate induit la signalisation de GPR40 qui est impliquée dans l’activation rapide des voies de signalisation Akt et ERK1/2. De son côté, l’effet prolifératif induit par l’oléate s’effectue par un mécanisme GPR40-indépendant, possiblement lié au métabolisme de l’oléate. / The relationship between obesity and cancer, although established by epidemiological studies, remains relatively unknown. However, about 25 % of cancers could be attributed to obesity. Among cancers that are affected by obesity, colon cancer, post-menopausal breast cancer and prostate cancer are the more frequent. Studies on animal models have suggested a positive association between high fat diets and de development of mammary and prostate cancer. We have studied the molecular mechanisms by which fatty acids influence breast and prostate cancer cells fate. This work has shown that unsaturated fatty acids, including oleate, can induce cellular proliferation while saturated fatty acids, including palmitate, reduce proliferation. An oleate treatment stimulates lipid droplets formation in the cytoplasm of breast cancer cells MDA-MB-231 and prostate cancer cells DU145 while a palmitate treatment induces apoptosis. The action mechanism of oleate on proliferation was studied more closely. Using pharmacological inhibitors, we determine that oleate-induced cell proliferation involves PI3K/Akt signaling pathway, ERK1/2 signaling pathway and the activation of one or many G protein coupled receptor(s) (GPCR). Oleate induces rapid Akt and ERK1/2 phosphorylation in breast cancer cells MDA-MB-231 and prostate cancer cells DU145. In the last few years, two GPCRs were identified as being activated by medium and long chain fatty acids, GPR40 and GPR120. GPR40 being expressed in many breast and prostate cancer cell lines while GPR120 expression was null in most cell lines tested, we studied the role of GPR40 in oleate-induced proliferation. Human epithelial mammary cells in primary culture did not express GPR40 nor GPR120 and failed to respond to oleate-induced cell proliferation or activation of signaling pathways. Akt and ERK1/2 signaling pathways activation by oleate in MDA-MB-231 and DU145 cells is potentiated by GPR40 over-expression and inhibited by the use of an siRNA directed against that receptor. However, oleate-induced cell proliferation does not seem to be affected by the presence of the siRNA directed against GPR40. Oleate being a fatty acid, it can enter cells freely by crossing the plasma membrane and part of its effects on proliferation could be attributed to its metabolism. A GPR40 agonist, GW9508, is able to activate GPR40 without entering the cells nor activating oleate’s metabolism. GW9508 stimulates Akt and ERK1/2 phosphorylation in breast cancer cells MDA-MB-231 and prostate cancer cells DU145, but does not induce cell proliferation as does oleate. These results help us to understand the action mechanism of oleate in breast and prostate cancer cells. Oleate induces GPR40 signalization which is involved in the rapid Akt and ERK1/2 signaling pathways activation. On the other hand, oleate-induced cell proliferation is carried out by a GPR40-independent mechanism, possibly linked to oleate’s metabolism.

Humans are approximately 99% similar with inter-individual differences caused in part by single-nucleotide polymorphisms (SNPs), which poses a challenge for the effective treatment of disease. Bioinformatics resources can help to store and analyse gene and protein information to address this challenge, however these resources have limitations, so the collation and biocuration of gene and protein information is required. Using the large conductance calcium- and voltage-activated potassium channel, also known as the Big Potassium (BK) channel as an example, due to its ubiquitous expression and widespread varied role in human physiology, this study aimed to prioritise SNPs with the potential to affect the function of the channel. Using a BK channel resource created with bioinformatics tools and published literature, mSlo SNPs H55Q and G57A, located in the S0-S1 linker, were prioritised and selected for lab-based verification. These SNPs flank three cysteine residues proven to modulate channel cellular distribution via palmitoylation, a reversible process shown to increase protein association with the cell membrane. The SNPs alter the predicted palmitoylation status of C56, one of the cysteine residues located in the S0-S1 linker. The cellular distribution of BK channels incorporating the SNPs was assessed using confocal microscopy and revealed that the direction and magnitude of SNP mimetic cell membrane expression was closely related to the C56 predicted palmitoylation score; a 'C56 palmitoylation pattern' was observed. It was shown that exposure to metabolic substrates glucose, palmitate and oleate modulated SNP-mimetic cellular distribution and could invert the 'C56 palmitoylation pattern', indicating that there is interplay between the metabolic status of the cell and the amino-acid composition of the channel via palmitoylation. The creation of a novel BK channel resource in this thesis highlighted the limitations, and inter-dependency of bioinformatics and lab based experimentation, whilst SNP verification experiments solidified the link between S0-S1 cysteine residues and BK cellular distribution. BK channel function is linked with a number of physiological processes; thus, the potential clinical consequences of the SNPs prioritised in this thesis require further research.

La relation entre l’obésité et le cancer, bien qu’établie par des études épidémiologiques, est peu connue. Pourtant, environ 25 % des cancers pourraient y être attribuables. Parmi les cancers reliés à l’obésité, les cancers du côlon, du sein chez les femmes ménopausées et de la prostate sont les plus fréquents. Des études sur modèles animaux ont suggéré une association positive entre une diète riche en gras et le développement du cancer mammaire et de la prostate. Nous avons étudié les mécanismes moléculaires par lesquels les acides gras influencent le devenir de lignées de cellules cancéreuses du sein et de la prostate. Ces travaux ont montré que les acides gras insaturés, dont l’oléate, induisent la prolifération cellulaire tandis que les acides gras saturés, dont le palmitate, diminuent la prolifération. Un traitement à l’oléate stimule la formation de gouttelettes lipidiques dans le cytoplasme des cellules de cancer du sein MDA-MB-231 et de la prostate DU145 alors qu’un traitement au palmitate entraîne l’apoptose. Le mécanisme d’action de l’oléate sur la prolifération a été étudié de façon plus approfondie. L’utilisation d’inhibiteurs pharmacologiques nous a permis de déterminer que l’effet prolifératif de l’oléate implique la voie PI3K/Akt, la voie ERK1/2 et l’activation d’un ou de plusieurs récepteur(s) couplé(s) aux protéines G (GPCR). L’oléate induit la phosphorylation rapide des protéines Akt et ERK1/2 dans les cellules de cancer du sein MDA-MB-231 et de la prostate DU145. Au cours des dernières années, deux GPCRs ont été identifiés comme étant activables par des acides gras à moyennes et à longues chaînes, GPR40 et GPR120. GPR40 étant exprimé dans plusieurs lignées cellulaires de cancer du sein et de la prostate contrairement à l’expression de GPR120 qui était inexistante dans la plupart des lignées, nous avons étudié l’implication de GPR40 dans l’effet prolifératif de l’oléate. Ces deux récepteurs n’étant pas exprimés dans les cellules épithéliales mammaires humaines en culture primaire, ces cellules ne répondent pas aux effets de l’oléate sur la prolifération et l’activation des voies de signalisation. L’activation des voies Akt et ERK1/2 par l’oléate dans les cellules MDA-MB-231 et DU145 est potentialisée par la surexpression du récepteur GPR40 et inhibée par l’utilisation d’un siRNA dirigé contre ce récepteur. Cependant, la prolifération induite par l’oléate ne semble pas affectée par la présence d’un siRNA dirigé contre GPR40. L’oléate étant un acide gras, il est capable d’entrer librement dans les cellules et une partie de ses effets sur la prolifération pourrait être attribuée à sa métabolisation. Un agoniste de GPR40, le GW9508, est en mesure d’activer GPR40 sans toutefois entrer dans les cellules ni activer le métabolisme de l’oléate. Le GW9508 stimule la phosphorylation des protéines Akt et ERK1/2 dans les cellules du cancer du sein MDA-MB-231 et de la prostate DU145, mais il n’est pas en mesure d’induire la prolifération cellulaire comme le fait l’oléate. Ces résultats nous permettent de mieux comprendre le mécanisme d’action de l’oléate sur les cellules de cancer du sein et de la prostate. L’oléate induit la signalisation de GPR40 qui est impliquée dans l’activation rapide des voies de signalisation Akt et ERK1/2. De son côté, l’effet prolifératif induit par l’oléate s’effectue par un mécanisme GPR40-indépendant, possiblement lié au métabolisme de l’oléate. / The relationship between obesity and cancer, although established by epidemiological studies, remains relatively unknown. However, about 25 % of cancers could be attributed to obesity. Among cancers that are affected by obesity, colon cancer, post-menopausal breast cancer and prostate cancer are the more frequent. Studies on animal models have suggested a positive association between high fat diets and de development of mammary and prostate cancer. We have studied the molecular mechanisms by which fatty acids influence breast and prostate cancer cells fate. This work has shown that unsaturated fatty acids, including oleate, can induce cellular proliferation while saturated fatty acids, including palmitate, reduce proliferation. An oleate treatment stimulates lipid droplets formation in the cytoplasm of breast cancer cells MDA-MB-231 and prostate cancer cells DU145 while a palmitate treatment induces apoptosis. The action mechanism of oleate on proliferation was studied more closely. Using pharmacological inhibitors, we determine that oleate-induced cell proliferation involves PI3K/Akt signaling pathway, ERK1/2 signaling pathway and the activation of one or many G protein coupled receptor(s) (GPCR). Oleate induces rapid Akt and ERK1/2 phosphorylation in breast cancer cells MDA-MB-231 and prostate cancer cells DU145. In the last few years, two GPCRs were identified as being activated by medium and long chain fatty acids, GPR40 and GPR120. GPR40 being expressed in many breast and prostate cancer cell lines while GPR120 expression was null in most cell lines tested, we studied the role of GPR40 in oleate-induced proliferation. Human epithelial mammary cells in primary culture did not express GPR40 nor GPR120 and failed to respond to oleate-induced cell proliferation or activation of signaling pathways. Akt and ERK1/2 signaling pathways activation by oleate in MDA-MB-231 and DU145 cells is potentiated by GPR40 over-expression and inhibited by the use of an siRNA directed against that receptor. However, oleate-induced cell proliferation does not seem to be affected by the presence of the siRNA directed against GPR40. Oleate being a fatty acid, it can enter cells freely by crossing the plasma membrane and part of its effects on proliferation could be attributed to its metabolism. A GPR40 agonist, GW9508, is able to activate GPR40 without entering the cells nor activating oleate’s metabolism. GW9508 stimulates Akt and ERK1/2 phosphorylation in breast cancer cells MDA-MB-231 and prostate cancer cells DU145, but does not induce cell proliferation as does oleate. These results help us to understand the action mechanism of oleate in breast and prostate cancer cells. Oleate induces GPR40 signalization which is involved in the rapid Akt and ERK1/2 signaling pathways activation. On the other hand, oleate-induced cell proliferation is carried out by a GPR40-independent mechanism, possibly linked to oleate’s metabolism.

SAMPAIO NETA, Nair do Amaral. Estudo da reação de produção de ésteres de ácidos graxos por via enzimática objetivando aplicações alimentícias. 2007. 99 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Tecnologia de Alimentos, Fortaleza-CE, 2007 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-05T15:42:42Z No. of bitstreams: 1 2007_dis_nasampaioneta.pdf: 429587 bytes, checksum: e95171ae3ed4bc0f19b43d878deb4444 (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-05T15:43:09Z (GMT) No. of bitstreams: 1 2007_dis_nasampaioneta.pdf: 429587 bytes, checksum: e95171ae3ed4bc0f19b43d878deb4444 (MD5) / Made available in DSpace on 2016-07-05T15:43:09Z (GMT). No. of bitstreams: 1 2007_dis_nasampaioneta.pdf: 429587 bytes, checksum: e95171ae3ed4bc0f19b43d878deb4444 (MD5) Previous issue date: 2007 / Several experiments were done aiming at the study on the enzymatic esterification of the oleic acid with fructose in ethanolic medium, focusing the synthesis of biodegradable biosurfactants. For that purpose, it was utilized the enzyme, Candida antartica B., at temperature of 55 ºC, in reacting time of 48, 72, 96 e 120 hours. Accordingly to the obtained results it was verified that the related enzyme catalyzed primarily the ethanol present in the reactional medium to form the ester: ethyl oleate. This fact was confirmed through magnetic nuclear resonance spectra (1H and 13C) as well as, through infrared spectrum, by the presence of absorption peak at 1738, 4 cm- 1, characteristic of that ester. The results of the reaction of ethyl oleate production indicate that the highest yield was observed in about 96 hours time, and for the 120 hours time it was observed also an inferior yield. The experiments accomplished for the obtention of fructose esters from oleic acids in ethanolic medium were not successful like in other solvents not recommended for food use. The ethyl oleate shows a lipophilic character and in the food industry it finds application in the osmotic dehydration of tomatoes and peppers “dedo de moça”, improving water release, sugar yield and solar brightness. The use of ethyl oleate in the dehydration process decreases the drying time increases its efficiency without leaving any traces pf chemical residues / Diversos experimentos foram realizados com o objetivo de estudar a reação de esterificação enzimática do ácido oléico com a frutose em meio etanólico, visando a síntese de biosurfactantes biodegradáveis. Para tanto, foi utizada a enzima Cândida Antartica B na temperatura de 55 °C e em tempos de reação variando entre 48, 72, 96 e 120 horas. De acordo com os resultados obtidos, constatou-se que a citada enzima catalisou preferencialmente o etanol presente no meio reacional para a formação do éster oleato de etila. Este fato foi confirmado através do espectro de ressonância magnética nuclear (1H e 13C), bem como do espectro de infravermelho pela presença de um pico de absorção em 1738,4 cm-1, característico deste éster. Os resultados da reação de formação do oleato de etila indicam que o maior rendimento da reação foi observado no tempo de 96 horas e que o tempo de 120 horas o rendimento foi inferior. Os experimentos realizados com o objetivo de se obter ésteres de frutose a partir do ácido oléico em meio etanólico não lograram êxito, apesar da literatura indicar a possibilidade de se realizar esta reação em outros meios que utilizam solventes não recomendados para o uso alimentício. O oleato de etila apresenta caráter lipofílico e na indústria de alimentos encontra aplicação na desidratação osmótica de tomates e pimentas do tipo “dedo de moça”, facilitando a perda de água, ganho de açúcar e cor mais luminosa. O uso do oleato de etila no processo de desidratação diminui o tempo de secagem, aumenta sua eficiência sem deixar nenhum tipo de resíduo químico.