Transesterification of cholesteryl esters

Zubillaga, M. P.; Maerker, G.

doi:10.1007/bf02542531

Cited by 14 publications

(7 citation statements)

References 21 publications

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“…It was succesfully used and described in detail in a recent method for the determination of the sum of free and esterified sterols in the analysis of edible oils by an online LC-GC method (Biedermann et al, 1993). The conditions for transesterification are mild compared with saponification, and triglycerides are converted to fatty acid methyl esters within minutes at room temperature (sterol esters need a slightly longer period of (1-2 h; Zubillaga and Maerker, 1988). Zubillaga and Maeker also demonstrated that no artifacts were formed during the reaction.…”

Section: Methods Developmentmentioning

confidence: 99%

Analysis of Polar Cholesterol Oxidation Products: Evaluation of a New Method Involving Transesterification, Solid Phase Extraction, and Gas Chromatography

Schmarr

Gross

Shibamoto

1996

J. Agric. Food Chem.

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Monitoring cholesterol oxidation products is important in the evaluation of the potential health risks associated with lipid oxidation. In the present study, a method allowing quick and reliable analysis of polar cholesterol oxidation products was evaluated. After Soxhlet-lipid extraction, the fat was transesterified under mild conditions, thereby minimizing degradation and allowing determination of the free and esterified cholesterol oxides. Sample fractionation was achieved with aminopropyl solid phase extraction cartridges and a stepwise elution with hexane, hexane/methyl tert-butyl ether, and acetone to separate polar cholesterol oxides from cholesterol and other lipid products. Further analysis of the trimethylsilyl derivatives was performed by gas chromatography with detection by flame ionization or mass spectrometry. A phytosterol oxide such as sitosterol R-epoxide (24R-ethyl-5R,6R-epoxycholestan-3β-ol) was employed for the first time as an internal standard for the quantification of cholesterol oxides in foodstuffs of animal origin.

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Section: Methods Developmentmentioning

confidence: 99%

Analysis of Polar Cholesterol Oxidation Products: Evaluation of a New Method Involving Transesterification, Solid Phase Extraction, and Gas Chromatography

Schmarr

Gross

Shibamoto

1996

J. Agric. Food Chem.

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“…Posteriormente, se separaron los productos de la hidrólisis mediante cromatografía en capa fina. Para esto, se sembraron 300 uL del extracto orgánico obtenido de cada hidrolizado y la cromatografía se desarrolló con una mezcla de éter de petróleo: éter etílico: ácido acético (80:20:1, v/v) (Zubillaga & Merker, 1988). Como estándar interno para cuantificar el grado de recuperación de los áci-dos grasos en los procedimientos de extracción y de separación, se agregó a los hidrolizados ácido heptadecanoico (C17:0) hasta 5% (p/p).…”

Section: Obtención E Identificación De Monoacilgliceroles Y De áCidosunclassified

Hidrólisis del aceite de coco (<i>Cocos nucífera</i> L) mediante enzimas estereoespecíficas y sin especificidad posicional.

Rodrı́guez¹,

Sanhueza²,

Valenzuela³

et al. 1997

Grasas y Aceites

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RESUMEN Hidrólisis del aceite de coco (Cocos nucífera L) mediante enzimas estereoespecíficas y sin especificidad posicional.El aceite de coco, por su composición, aporta a la dieta principalmente ácidos grasos de cadena corta y media, los que desde el punto de vista nutricional tienen ventajas, debido a su rápida utilización metabólica que permite brindar energía, principalmente a nivel hepático. Es importante contar con procedimientos que permitan obtener estos ácidos grasos en forma libre a partir del aceite de coco, ya que de esta manera pueden ser utilizados con diferentes fines, ya sea nutricionales, farmacológi-cos o tecnológicos. En el presente trabajo se estudió la hidrólisis del aceite de coco producida por dos tipos de lipasas; una lipasa sin especificidad posicional obtenida de Candida cylindracea, y otra lipasa sn-1',3' estereoespecífica, obtenida de Mucor miehei, en forma libre e inmovilizada (LIpozyme IM-20). La lipasa de Candida cylindracea hidroliza un 85%-90% de los triacilgliceroles del aceite a las 47-50 horas de acción. La composición del hidrolizado es muy similar a la del aceite, y en los monoacilgliceroles remanentes la composición de ácidos grasos es poco definida, aunque predominan los de cadena corta (C6 y C8) y media (C10-C14). La enzima de Mücor n?/e/?e/permite alcanzar sólo un 65% de hidrólisis, que se obtiene a las 30 horas en el caso de la enzima libre y a las 10 horas en el caso de la enzima inmovilizada (Lipozyme IM-20). La composición de ácidos grasos del hidrolizado es muy similar en ambos casos, destacando la presencia de ácidos grasos en el rango C8-C14, aunque con una composición muy diferente a la del aceite original. La composición de ácidos grasos del monoacilglicerol remanente muestra una marcada predominancia de ácido láurico (C12:0) en el producto de ambas formas de la enzima, lo cual indicaría que este ácido graso ocupa mayoritariamente la posición sn-2' de los triacilgliceroles del aceite de coco. Se discute la utilidad de las lipasas para obtener fracciones enriquecidas en ciertos ácidos grasos. También se discute la posible utilidad de la enzima de Mucor miefiei para obtener fracciones enriquecidas en ácido láurico, el que por saponificación posterior puede ser obtenido en forma libre. PALABRAS-CLAVE: Aceite de coco -Enzima estereoespecífica -Enzima sin especificidad posicional -Hidrólisis. SUMMARY Hydrolysis of coconut oil (Cocos nucífera L.) by specificity and no positional specificity enzimes.The characteristic fatty acid composition of coconut oil provides mainly short-and medium-chain fatty acids when incorporated to the diet. These fatty acids have nutritional advantages because their metabolic disposition allows the rapid obtention of energy, mainly at the hepatic level. The obtention of short-and medium-chain fatty acids from coconut oil as substrate, may be of importance because the different nutritional, pharmacological, and technological uses of these fatty acids. In the present work, the effect of two type of lipases on the hydrolysis of coconut oil was...

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“…2A). The yield of methyl oleate was higher than 94%, indicating that methyl propionate served as a good substitute for benzene or diethyl ether, which had been used earlier (4,5). Wax, i.e., long-chain FA esters of higher alcohols, and sterol esters are also resistant to methanolysis under the conditions for glycerolipids (2).…”

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confidence: 94%

“…This is one of the reasons why sterol esters do not react with methanolic KOH under the same conditions as those used for glycerolipids. Fortunately, a few convenient methods have been developed for the preparation of FAME from sterol esters by alkali-catalyzed methanolysis (4,5). These methods, however, utilize harmful solvents such as benzene or diethyl ether.…”

mentioning

confidence: 99%

Preparation of FAME from sterol esters

Ichihara

Yamaguchi

Nishijima

et al. 2003

J Americ Oil Chem Soc

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Sir:Glycerolipids, including TAG and phospholipids, are easily converted into FAME by alkali-catalyzed methanolysis for GC analysis of the FA compositions. Although CH 3 ONa is most commonly used as an alkali, NaOH-or KOH-catalyzed methanolysis is very convenient and useful (1,2). The procedure is not only simple and rapid but also safe. In contrast, the preparation of FAME from sterol esters is more difficult than that for glycerolipids. For example, FAME can be prepared from many samples of small amounts of blood or breast milk by KOH-catalyzed methanolysis on small pieces of filter paper

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Transesterification of cholesteryl esters

Cited by 14 publications

References 21 publications

Analysis of Polar Cholesterol Oxidation Products: Evaluation of a New Method Involving Transesterification, Solid Phase Extraction, and Gas Chromatography

Analysis of Polar Cholesterol Oxidation Products: Evaluation of a New Method Involving Transesterification, Solid Phase Extraction, and Gas Chromatography

Hidrólisis del aceite de coco (<i>Cocos nucífera</i> L) mediante enzimas estereoespecíficas y sin especificidad posicional.

Preparation of FAME from sterol esters

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