The isolation of the polyunsaturated acids of the fish oils as their methyl esters by preparative scale gas chromatography

Preparative gas chromatography and its applications

Although hundreds of papers related to preparative gas chromatography (pGC) have been published since the late 1950s, the success of the GC technique has largely been associated with analytical instead of preparative purposes. Actually, pGC is an ideal alternative technique for the preparation of pure substances, especially volatile compounds. This paper reviews the papers (written in English) associated with pGC published over the period from the 1950s to the 2010s. For large scale preparation, large sample injection and vaporization, a high loading capacity column, a gas splitter at the end of the column and a special collecting device are fundamentally important for a pGC system. The primary components of pGC system, including injector, column, splitter, detector and collection traps, are briefly introduced. Furthermore, the applications of pGC in the separation and purification of volatile compounds from natural essential oils, in addition to the purification of isotopes, isomers and enantiomers are summarized.

Downstream processing of algal polyunsaturated fatty acids

Little information exists on recovering polyunsaturated fatty acids from microalgae; however, methods for concentration and purification of PUFAs from fish oil have been extensively reported. This review examines recovery and purification of microalgae derived PUFAs, but techniques developed for use with fish oil are also reviewed as being potentially useful for concentration and purification from microalgae. The two main techniques for concentrating and purifying-urea fractionation and high performance liquid chromatography-are discussed in depth and attention is focused on the process developed by the authors for obtaining highly pure PUFA. Other potentially useful techniques, such as supercritical fluid extraction and lipase-catalyzed processing are detailed.

Docosahexaenoic acid is a strong inhibitor of prostaglandin but not leukotriene biosynthesis

Docosahexaenoic acid (DCHA), a major polyunsaturated acid component of fish lipid, is not a substrate for prostaglandin synthetase from ram seminal vesicles but is a strong competitive inhibitor (Ki, 0.36 microM) of the conversion by this enzyme of arachidonate (Km, 5.9 microM) to prostaglandins. In contrast, DCHA exhibits little interference to the conversion of arachidonate to metabolites on the leukotriene pathway. DCHA is a very poor substrate for the leukotriene-synthesizing system from RBL-1 cells and no formation of the C22 analog of leukotriene B could be detected from it. The C22 analog of leukotriene C4 was produced by chemical synthesis from DCHA and found to be less than 1/10,000th as active as leukotriene C4 in contracting guinea pig ileum. The DCHA used in this work was obtained in greater than 99.8% purity by a practical process developed for its separation from fish lipid. The cardiovascular protective effects ascribed to dietary intake of fish lipid by certain populations may be due in part to the biological action of DCHA, including the inhibition of prostaglandin biosynthesis.