title: The Assignment of the Absolute Configuration of C-22 Chiral Center in the Aglycones of Triterpene Glycosides from the Sea Cucumber Cladolabes schmeltzi and Chemical Transformations of Cladoloside C.
abstract: The absolute R-configuration of the C-22 chiral center in cladoloside C (1) and therefore in all related glycosides isolated from the sea cucumber Cladolabes schmeltzii has been assigned by Mosher's method. Some chemical transformations of the native glycoside 1 were carried out to apply this method. This resulted in the isolation and elucidation of chemical structures of progenin 2 and artefact aglycones 3 and 4, obtained from 1 and assignment of the absolute R-configuration of C-22 in the progenin 2. The coincidence of C-22 configurations in the studied compounds with those of the earlier known lanostane-type aglycone of frondoside C and holostane-type aglycone of cladoloside C (1) confirms the generic biosynthetic pathways to different types of sea cucumber glycoside aglycones. It suggests the same R-configuration of C-22 chiral centers in all the sea cucumber glycosides having C-22 functionalities.
authors.forename: Anatoly I
authors.initials: AI
authors.lastname: Kalinovsky
authors.forename: Alexandra S
authors.initials: AS
authors.lastname: Silchenko
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Avilov
authors.forename: Vladimir I
authors.initials: VI
authors.lastname: Kalinin
mesh_terms: D000818:Animals; D008968:Molecular Conformation; D012616:Sea Cucumbers / Q000737:chemistry*; D014315:Triterpenes / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D014315:Triterpenes; C000602586:cladoloside C