Analysis of the iridals in rhizome extracts of Iris variegata Linn.

Fractionation of the lipid extract from rhizomes of Iris variegata Linn. resulted in the isolation of one new and four known iridals. The latter were identified by comparison with authentic standards and NMR-spectroscopic analyses as 21-hydroxyiridal 1, 21-hydroxy-10-deoxyiridal 2, 16-hydroxyiridal 3 and 22-methyl-gamma-cycloiridal 4. The (R) configuration of C21 in compound 2 was determined by the exciton chirality method. The same stereochemistry has previously been found for the appropriate moieties in 1 and 3. Based on its spectroscopic properties the new triterpenoid was shown to be the 23-hydroxyiridal 5.