Purification of the isoflavonoid puerarin by adsorption chromatography on cross-linked 12% agarose

The isoflavonoid puerarin in extracts of the well-known traditional Chinese drug Radix puerariae (root of the plant Pueraria lobata) can be separated from other isoflavonoids by adsorption chromatography on the cross-linked 12% agarose gel Superose 12 equilibrated in distilled water. The adsorption is totally quenched by the addition of 50% acetic acid. The separation of the isoflavonoids is tentatively ascribed to interaction with the residues of the cross-linking reagents used in the manufacturing process of Superose 12. Thus, no useful separation can be achieved with non-cross-linked 12% agarose gel media. Symmetric elution profiles at high sample loadings (16 mg on a 24 ml column) suggest linear adsorption isotherms for the isoflavonoids.