Two-dimensional nuclear Overhauser enhancement NMR experiments on pelargonidin-3-glucopyranoside, an anthocyanin of low molecular mass.
Pelargonidin-3-glucoside has been isolated from the acidified methanolic extract of strawberries (Fragaria anannassa variety Corona) by successive application of an ion-exchange resin, droplet-counter chromatography and gel filtration. The pigment in acidified methanolic solution was studied by means of the two-dimensional nuclear Overhauser enhancement NMR technique, and the sugar unit was found to be attached to the 3-position on the aglycone. At +20 degrees C the pigment was found to be in the extreme narrowing limit where the NOESY cross-peaks are negative. However, at -20 degrees C this low-mass anthocyanin could be studied in the slow motion regime where the NOESY cross-peaks are positive. With a mixing time of 0.3 s, the glucose H1"-H4" proton pair was measured in the initial cross-relaxation rate and their cross-peak volume corresponded to the H1"-H4" distance found in a 4C1 chair conformation.
Nerdal
W
W
Department of Chemistry, University of Bergen, Norway.
Pedersen
A T
AT
Andersen
O M
OM
D000872:Anthocyanins / Q000737:chemistry*; D005419:Flavonoids / Q000737:chemistry*; D005638:Fruit; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008968:Molecular Conformation; D008970:Molecular Weight; D010860:Pigments, Biological / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry*; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet; D013057:Spectrum Analysis / Q000379:methods; D013696:Temperature
D000872:Anthocyanins; D005419:Flavonoids; D010860:Pigments, Biological; D010936:Plant Extracts; C078485:pelargonidin-3-glucoside