Chromium(III)-docosahexaenoic acid complex: Synthesis and characterization

Supplements containing chromium in its trivalent oxidation state [Cr(III)] are used by diabetic patients to improve their glucose and insulin levels and omega-3 fatty acids are also beneficial for people with insulin resistance or diabetes. It seemed very useful to combine chromium(III) and omega-3 functional entities into single molecules. Here we synthesized and characterized a chromium cis-4,7,10,13,16,19-docosahexaenoic acid (DHA) complex, one of the two main components of the heterogeneous chromium(III) fish oil omega-3 concentrate products. Ethyl cis-4,7,10,13,16,19-docosahexaenoate was hydrolyzed with sodium hydroxide, and the generated salt was reacted in situ with chromium(III) chloride hexahydrate and converted into an oxo-centred trinuclear chromium(III) complex. A study of the DHA-chromium(III) complex by liquid chromatography/tandem mass spectrometry/(LC/MS/MS) is reported in this work. The data suggest a triaqua-mu 3-oxohexakis-mu-docosahexa-enoatotrichromium(1+), [Cr(3)O(C(22)H(31)O(2))(6)(H(2)O)(3)](+), core structure. (C) 2009 Elsevier Ltd. All rights reserved.