The Conversion of Parkeol into its 24,25-Epoxide by Tissue Cultures of Nicotiana tabacum

Abstract

Tissue cultures of Nicotiana tabacum were incubated with [25-14C]parkeol. The resulting sterols, 4-methylsterols and 9,19-cyclo-24-lanosten-3β-ol (cycloartenol), were found to be devoid of radioactivity. Another product, which is shown to be 24,25-epoxy-9(11)-lanosten-3β-ol, was radioactive. Furthermore, the natural existence of 24,25-epoxycycloartanol is inferred. It is concluded that parkeod does not fulfill the requirements of a phytosterol precursor, although it is incorporated in another natural pathway.