[2-13C]Mevalonic acid and [5-13C]mevalonic acid were fed to cultured cells of sunflower and the resulting biosynthesized [13C]sitosterols were examined by 13C NMR spectroscopy. The observations confirmed the biochemically predictable positions of 13C labels in sitosterol. Based on the new information a mechanism for the biogenesis of the C-24 alkyl group in phytosterols is given.
- Helianthus annus
- mechanism of C-24 alkylation.
- sterol biosynthesis