Analysis of Polyprenols in Eucommia ulmoides by Supercritical Fluid Chromatography

Abstract

The use of supercritical fluid chromatography (SFC) for the analysis of plant polyprenols has been described. Compared with conventional high-performance liquid chromatography, the use of SFC markedly improved the chromatographic resolution of polyprenol homologues and their geometric isomers. Under optimized SFC conditions, individual homologues from 10 to 100 mers were separated. It was also possible to isolate each geometric isomer of polyprenol homologues from 13 to 20 mers by fractionation by using SFC. The chain-length distributions of polyprenol samples determined by SFC essentially agreed with those determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. SFC analysis of the polyprenols extracted from the leaf, root, and seed coat of the rubber-producing plant Eucommia ulmoides revealed the presence of all trans polyprenols with degrees of polymerizations greater than 10 for the first time in nature. The all trans polyprenols had broad distributions of chain-length leading to high molecular weight; this suggests that the polyprenols act as biosynthetic intermediates for the high molecular weight trans-1,4-polyisoprene in this plant. The chain-length distributions of the trans polyprenols from the leaf, root, and seed coat differed from each other, suggesting the presence of site-specific control mechanisms for chain termination. On the other hand, cis polyprenols have been found to occur in all parts of E. ulmoides. They had narrow chain-length distributions similar to those of dolichols.