Sequence analysis of polyprenols by 500 MHz 1H-NMR spectroscopy

Abstract

Polyprenols containing two- trans and poly- cis isoprene units were differentiated from those containing three- trans and poly- cis isoprene units by using the methyl proton signals in the 1H-NMR spectrum at 500 MHz in C 6D 6 solution. The methyl proton signals in the 1H-NMR spectra of geraniol, nerol, farnesol isomers, geranylgeraniol; amd geranylnerol were analyzed with the aid of two-dimensional 1H- 1H and 1H- 13C shift correlation NMR spectroscopy as the model compounds of polyprenols. On the basis of these signal assignments, the 1H-NMR spectra of solanesol, synthetic dolichol-19, polyprenol-11 and -12 extracted from silkworm feces, and polyprenol-17 and -18 obtained from the leaves of Ginkgo biloba were analyzed at a digital resolution of 0.00035 ppm. The methyl proton signals of the polyprenols were found to split in terms of triad sequence of trans and cis isoprene units. The signal characteristic to the trans- trans-trans sequence was observed at 1.621 ppm in the spectrum of the three- trans polyprenols.