Localization of iridals in Iris germanica rhizomes

Analysis of iridals in Iris germanica rhizomes of different ages indicated a higher level of these triterpenoids in young rhizomes. The analysis of small discs of rhizomes prepared from slices indicated an increasing dorso-ventral gradient of iridal amounts in 1- and 2-year-old rhizomes. Iridal composition was also found to differ, depending on the age of the rhizomes. Monocycloiridals are mostly represented in young rhizomes whereas cycloiridals appeared to be the main iridal form in the old ones, The study of the ratio free iridals (FI)/iridal esters (IE) revealed a higher ratio in the youngest rhizomes. Localization of iridals within rhizomes is correlated with previous results concerning their possible role and their biosynthesis in the plant.