Polyprenol structural characterization

This paper describes the structural analysis of naturally occurring ois-1,4 polyisoprenes using 13C NMR spectroscopy. First, the structural characterization of polyprenols, which are linear isoprenoid compounds containing 30 to 100 carbons, was carried out on the basis of information obtained from acyclic terpenes having various ois and trans isoprene units as model compounds. This method was also applied to the structural analysis of polyisoprenes. The elucidation of the structure of the end groups and the arrangement of isoprene units provides information on the mechanism of the biosynthesis of polyprenyl compounds in nature. 

Table I summarizes the plant polyprenols that have been isolated and whose sources and some structural aspects have been characterized. These polyprenols occur in different species as mixtures, differing from each other in one isoprene unit. One or two members of the family are very abundant and normally account for 80% of the total polyprenol content of the plant. Most long-chain polyprenols have Z, E double bonds, the E-isoprene units being adjacent to the -residue and to a variable number of Z residues, depending on the plant (see Table I).

---