The application of multidimensional NMR analysis to cis/trans isomers study of menaquinone-7 (vitamine K2MK-7), identification of the (E,Z3,E2,omega)-menaquinone-7 isomer in dietary supplements

摘要

The aim of this paper was to determine the chemical structure of cis/trans isomers of vitamin K2MK-7 found in dietary supplements. Vitamin K2MK-7 was extracted, along with contamination in the form of cis/trans isomers of menaquinone-7, from dietary supplements through tetrahydrofuran and then subjected to fractionation using the semi-preparative chromatography column with cholesteryl group phase (strong stereoselectivity for hydrophobic compounds). The obtained fractions of cis/trans isomers of menaquinone-7 underwent analysis with the use of multidimensional NMR methods optimized for maximum signal separation. NMR analysis made it possible to identify the first geometric isomer of (E,Z3,E2,omega)-menaquinone-7, which underwent NMR comparative analysis with a known "full trans" isomer. It was also possible to confirm the presence of other cis/trans isomers in menaquinone-7 in the collected fractions. Due to the fact that the other fractions indicate a mixture of at least two geometric isomers of menaquinone-7, it was not possible to conduct full structural identification. 2018 Elsevier B.V. All rights reserved.