The mechanism of the enzymic induced flavanone - isoflavone change.

✍ Scribed by Leslie Crombie; Donald A. Whiting

• Publisher: Elsevier Science
• Year: 1992
• Tongue: French
• Weight: 243 KB
• Volume: 33
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)92530-9

✦ Synopsis

A new scheme for the P 450 enzymic conversion of flavanones into isofiavones, which surmounts known experimental constknts, is propo&ed.

An important phase in the biosynthetic construction of rotenoids such as rotenone. amorphigenin and deguelin is the conversion of liquiritigenin (1) into 4'-Qmethyldaidzein ( ), which we showed involves migration of ring-A from C-2 of the former to C-3 of the latter. l,* ills is a general problem of isoflavonoid biosynthesis which has been recognised for more than 30 years without a fully convincing mechanism being arrived at.3 It has been shown that conversion of (1) into (4) or (2) into ( ) is initiated by isoflavone synthase, a P-450 iron-containing microsomal enzyme of the endoplasmic reticulum of elicitor treated so~bean.~*~ The first product is (3) which is then dehydrated by a separate soluble enzyme: the latter has no requirement for NADPH or dioxygen.4*5 Any fully plausible mechanism must take account of certain constraints.