Phytochemical investigation of Colophospermum mopane

Abstract

A previously partially-characterized diterpene alcohol was isolated from Colophospermum mopane, and its structure completely elucidated. A second novel diterpene alcohol, structurally related to the first, was also fully characterized by NMR spectroscopy. A proposed precursor of the diterpenes, a mixed pair of diterpene aldehydes, was isolated, and upon reduction yielded a mixture of both diterpene alcohols. These diterpenes represent important 'missing' links in the biogenesis of 9,13-epoxylabdanes. Seeds of C. mopane were grown in greenhouse conditions to determine when these diterpenes were produced. Two sesquiterpenes and two diterpenes were quantified by GC-MS. Seedlings grown from seeds rinsed in hexane grew faster and produced terpenoids sooner than the control group. It is likely that C. mopane seeds have terpenoids present in concentrations high enough to minimize competition from herbaceous perennials, at the cost of some degree of auto-toxicity, so rinsing promotes growth and terpenoid production.