Calycosin is an ''O''-methylated isoflavone. It can be isolated from ''

Astragalus membranaceus ''Astragalus propinquus'' (syn. ''Astragalus membranaceus'', commonly known as Mongolian milkvetch in English; 'Хунчир' in Mongolian; ''huáng qí'' (), ''běi qí'' () or ''huáng huā huáng qí'' (), in Mongolia, is a flowering plant i ...

'' Bge. var. ''mongholicus'' and ''

Trifolium pratense ''Trifolium pratense'', the red clover, is a herbaceous species of flowering plant in the bean family Fabaceae, native to Europe, Western Asia, and northwest Africa, but planted and naturalized in many other regions. Description Red clove ...

'' L. (red clover).

Biosynthesis

Isoflavone 3′-hydroxylase uses

formononetin Formononetin is an O-methylated isoflavone. Natural occurrences Formononetin is found in a number of plants and herbs such as red clover. Along with other phytoestrogens, it predominantly occurs in leguminous plants and Fabaceae, particularly i ...

, NADPH, H⁺ and O₂ to produce calycosin, NADP⁺ and H₂O.

References

O-methylated isoflavones {{phenol-stub