title: Transformation of naturally-occurring 1,9-trans-9,5-cis sweroside to all trans sweroside during acetylation of sweroside aglycone.
abstract: From the rootstock of Scabiosa columbria L. loganin and sweroside were isolated. Sweroside showed moderate antibacterial activity. Pure sweroside was converted to the sweroside aglycone 1-acetoxy derivative (DABCO/Ac2O) after hydrolysis of the glucose unit. X-ray crystallography of the monoacetate showed unambiguously that it had been transformed to a new seco-iridoid having the novel trans diaxial configuration for the protons on C-1, C-9 and C-5. The mechanism for the rearrangement is discussed.
authors.affiliation: School of Chemical and Physical Sciences, University of Natal, Scottsville, South Africa.
authors.forename: M M
authors.initials: MM
authors.lastname: Horn
authors.forename: S E
authors.initials: SE
authors.lastname: Drewes
authors.forename: N J
authors.initials: NJ
authors.lastname: Brown
authors.forename: O Q
authors.initials: OQ
authors.lastname: Munro
authors.forename: J J
authors.initials: JJ
authors.lastname: Meyer
authors.forename: A D
authors.initials: AD
authors.lastname: Mathekga
mesh_terms: D000107:Acetylation; D001711:Biotransformation; D018360:Crystallography, X-Ray; D005960:Glucosides / Q000096:biosynthesis* / Q000737:chemistry; D057888:Iridoid Glucosides; D039823:Iridoids; D009682:Magnetic Resonance Spectroscopy; D011714:Pyrans / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D005960:Glucosides; D057888:Iridoid Glucosides; D039823:Iridoids; D011714:Pyrans; C049412:sweroside