- Identification of flavone glucuronide isomers by metal complexation and tandem mass spectrometry: Regioselectivity of uridine 5′-diphosphate- glucuronosyltransferase isozymes in the biotransformation of flavones
-
Flavone glucuronide isomers of five flavones (chrysin, apigenin, luteolin, baicalein, and scutellarein) were differentiated by collision-induced dissociation of [Co(II) (flavone-H) (4,7-diphenyl-1,10-phenanthroline) 2]+ complexes. The complexes were generated via postcolumn addition of a metal-ligand solution after separation of the glucuronide products generated upon incubation of each flavone with an array of uridine 5′-diphosphate (UDP)-glucuronosyltransferase (UGT) isozymes. Elucidation of the glucuronide isomers allowed a systematic investigation of the regioselectivity of 12 human UGT isozymes, including 8 UGT1A and 4 UGT2B isozymes. Glucuronidation of the 7-OH position was the preferred site for all the flavones except for luteolin, which possessed adjacent hydroxyl groups on the B ring. For all flavones and UGT isozymes, glucuronidation of the 5-OH position was never observed. As confirmed by the metal complexation/MS/MS strategy, glucuronidation of the 6-OH position only occurred for baicalein and scutellarein when incubated with three of the UGT isozymes.
- Robotham, Scott A.,Brodbelt, Jennifer S.
-
-
Read Online
- Purification and characterization of UDP-glucuronate: Baicalein 7-O- glucuronosyltransferase from Scutellaria baicalensis Georgi. cell suspension cultures
-
UDP-glucuronate: baicalein 7-O-glucuronosyltransferase (UBGAT) catalyzes the transfer of glucuronic acid from UDP-glucuronic acid to the 7-OH of baicalein. UBGAT was purified from cultured cells of Scutellaria baicalensis Georgi (Lamiaceae). It was purified 95-fold using various chromatography and chromatofocusing procedures to apparent homogeneity. The M(r) was estimated to be 110 kDa by gel filtration chromatography with a 52 kDa subunit by SDS- PAGE. The isoelectric point was pH 4.8. UBGAT was specific to UDP-glucuronic acid as a sugar donor and flavones with substitution ortho- to the 7-OH group such as baicalein (6-OH), scutellarein (6-OH) and wogonin (8-OMe). (C) 2000 Elsevier Science Ltd.
- Nagashima, Shigeyuki,Hirotani, Masao,Yoshikawa, Takafumi
-
-
Read Online
- Preparation and characterization of the inclusion complex of Baicalin (BG) with β-CD and HP-β-CD in solution: An antioxidant ability study
-
The formation of the complexes of BG with β-CD and HP-β-CD was studied by UV-vis absorption spectroscopy, fluorescence spectra, Phase-solubility measurements and nuclear magnetic resonance spectroscopy (NMR) in solution. The formation constants (K) of com
- Li, Jinxia,Zhang, Min,Chao, Jianbin,Shuang, Shaomin
-
scheme or table
p. 752 - 756
(2009/09/26)
-
- Synthese von Baicalin und einiger anderer Baicalein-glycoside
-
The 6- and 7-O-β-glucopyranosides 14 and 7 and the 6- and 7-O-β-glucopyranosiduronic acids 18 and 9 of baicalein (1) have been synthesized. 9 was identical with baicalin but 14 and tetuin, further 18 and a "baicalin-6-glucuronide" from Oroxylum indicum were different.
- Mezey-Vandor, Gabriella,Farkas, Lorand,Kanzel, Ida,Nogradi, Mihaly
-
p. 1945 - 1949
(2007/10/02)
-