REACTION-MECHANISM OF OXIDATIVE REARRANGEMENT OF FLAVANONE IN ISOFLAVONE BIOSYNTHESIS

被引:77
作者
HASHIM, MF [1 ]
HAKAMATSUKA, T [1 ]
EBIZUKA, Y [1 ]
SANKAWA, U [1 ]
机构
[1] UNIV TOKYO,FAC PHARMACEUT SCI,7-3-1 HONGO,BUNKYO KU,TOKYO 113,JAPAN
关键词
Cytochrome P-450; Elicitor; Isoflavone synthesis; Isoflavonoid; Pueraria lobata; Rearrangement;
D O I
10.1016/0014-5793(90)80410-K
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Microsomes that were prepared from elicitor-treated Pueraria lobata cell cultures catalyzed the conversion of liquiritigenin, a flavanone, into daidzein, an isoflavone. The reaction was resolved into two steps. 2, 7, 4'-Trihydroxyisoflavanone was formed as a major product when liquiritigenin was incubated with carefully washed microsomes in the presence of NADPH. The structure of 2, 7, 4'-trihydroxyisoflavanone was confirmed by mass and 1H NMR spectroscopies. The enzyme responsible for this rearrangement reaction is a cytochrome P-450-dependent monooxygenase. Upon treatment with a soluble enzyme fraction 2, 7, 4'-trihydroxyisoflavone yielded daidzein quantitatively. The incorporation of 18O from 18O2 into the 2-hydroxy group of 2, 7, 4'-trihydroxyisoflavanone was demonstrated by the shift of molecular ion in its mass spectrum. Based on these observations a new reaction mechanism, hydroxylation associated with 1,2-migration, is proposed for the oxidative rearrangement reaction catalyzed by the cytochrome P-450 enzyme of Pueraria lobata. © 1990.
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页码:219 / 222
页数:4
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