Search

This report describes the synthesis of reversed structured 1-O-alkyl-2,3-diacylsn-glycerols (DAGEs) possessing a pure saturated even number fatty acid (C6:0-C16:0) at the sn-2 position along with a pure EPA or DHA located at the terminal sn-3 position of the glycerol backbone of chimyl, batyl and selachyl alcohols. These adducts were synthesized by a highly efficient two-step chemoenzymatic process involving an immobilized Candida antarctica lipase to introduce pure EPA and DHA activated as oxime esters exclusively to the sn-3 terminal position of enantiopure chimyl, batyl and selachyl alcohols in excellent yields. The saturated fatty acids were subsequently incorporated to the remaining sn-2 position of the resulting 3-monoacylglyceryl ethers (3-MAGEs) using EDAC coupling agent in the presence of DMAP in very high to excellent yields (85%-98%). No losses of enantiomeric composition were observed during these processes. The multiple utilities of the resulting focused library of reversed structured DAGEs are discussed including how such compounds may possibly be utilized within the pharmaceutical area. [ABSTRACT FROM AUTHOR]

A highly efficient two-step chemoenzymatic synthesis of structured triacylglycerols comprising a pure n-3 polyunsaturated fatty acid at the mid-position and a pure saturated fatty acid located at the end-positions is described. In the first step an immobilized Candida antarctica lipase was observed to display an excellent regioselectivity toward the end-positions of glycerol at 0–4°C using vinyl esters as acylating agents. The n-3 fatty acids were introduced into the remaining mid-position highly efficient and in excellent yields using EDCI coupling agent. [Copyright &y& Elsevier]

• First study on the oxidative stability of DHA in regio- and enantiopure TAGs. • DHA in sn -2 was the most stable structure with or without RRR -α-tocopherol. • Without tocopherol, oxidative stability of DHA in sn -1 and sn- 3 was comparable. • With RRR -α-tocopherol, higher stability of DHA in sn -1 compared to sn -3. • Diastereomeric interactions between RRR -α-tocopherol and DHA in sn -1 is proposed. Docosahexaenoic acid (DHA) is essential for health but easily oxidized. Yet the influence of DHA's exact location (sn -1, sn -2, or sn -3) in triacylglycerols on oxidative stability is currently unknown. This is the first study comparing oxidative stability of DHA in regio- and enantiopure triacylglycerols with or without RRR -α-tocopherol. Headspace solid-phase micro-extraction with gas chromatography–mass spectrometry, liquid chromatography–mass spectrometry, and nuclear magnetic resonance spectroscopy were applied. DHA in sn -2 was the most stable with or without added RRR -α-tocopherol resulting in differences in hydroperoxide formation. Without antioxidant, stability of DHA in sn -1 and sn -3 was mainly similar, with slight tendency towards better stability in sn -3. With RRR -α-tocopherol higher stability in sn -1 compared to sn -3 was observed. This points to diastereomeric interactions between RRR -α-tocopherol and DHA in sn -1. These results are highly relevant for enzymatic restructuring processes of DHA-rich fish or microalgae oil concentrates aimed for food supplements or food fortification. [ABSTRACT FROM AUTHOR]