Transformation of naturally-occurring 1,9-trans-9,5-cis sweroside to all trans sweroside during acetylation of sweroside aglycone.
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.
Horn
M M
MM
School of Chemical and Physical Sciences, University of Natal, Scottsville, South Africa.
Drewes
S E
SE
Brown
N J
NJ
Munro
O Q
OQ
Meyer
J J
JJ
Mathekga
A D
AD
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
D005960:Glucosides; D057888:Iridoid Glucosides; D039823:Iridoids; D011714:Pyrans; C049412:sweroside