title: The thermal and enzymatic taxifolin-alphitonin rearrangement.
abstract: This report describes a detailed investigation of the thermal and enzymatic conversion of taxifolin to alphitonin. Chromatographic separation of the four dihydroquercetin stereoisomers 1-4 in combination with circular dichroism spectroscopy permitted elucidation of the kinetics of this rearrangement and characterization of the different reaction pathways involved. Our findings are corroborated by quantum chemistry calculations that reveal a unique cascade of tautomerization processes leading from taxifolin to alphitonin and also explain the racemization of alphitonin at room temperature. Furthermore, the substrate specificity toward (+)-taxifolin of an enzyme from Eubacterium ramulus catalyzing this intriguing rearrangement is demonstrated.
authors: Pharmaceutical Chemistry I, Pharmaceutical Institute, University of Bonn, 53121 Bonn, Germany. paul.elsinghorst@uni-bonn.de
authors: Paul W
authors: PW
authors: Elsinghorst
authors: Taner
authors: T
authors: Cavlar
authors: Anna
authors: A
authors: Müller
authors: Annett
authors: A
authors: Braune
authors: Michael
authors: M
authors: Blaut
authors: Michael
authors: M
authors: Gütschow
mesh_terms: D001572:Benzofurans / Q000737:chemistry* / Q000378:metabolism; D002384:Catalysis; D002942:Circular Dichroism; D005051:Eubacterium / Q000201:enzymology*; D007535:Isomerases / Q000378:metabolism*; D015394:Molecular Structure; D011794:Quercetin / Q000031:analogs & derivatives* / Q000737:chemistry; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D001572:Benzofurans; C569082:alphitonin; D011794:Quercetin; C003377:taxifolin; D007535:Isomerases; C569081:taxifolin isomerase, Eubacterium ramulus