Structure of Lansiosides: Biologically Active new Triterpene Glycosides from Lansium domesticum

From the extract of the fruit peel of Lansium domesticum (Meliaceae), three new triterpene glycosides, named lansiosides A, B, and C, have been isolated. Their structures and absolute configurations have been established to be 1, 2, and 3, respectively, by spectral analysis and chemical derivatization. Each lansioside provides on methanolysis the same aglycon, methyl lansiolate (4), which is a representative of a class of new triterpenoids with a secoonocerane framework. Lansioside A (1) is a very rare example of an amino sugar glycoside from a plant and has unique biological behavior. Lansioside A inhibits the leukotriene D4 induced contraction of guinea pig ileum in 2.4 ppm concentration effectively.