Patent ID: 8193345

Claim:
A method of separating a lactone compound FK506 from a mixture, the method comprising: providing a mixture which comprises the lactone compound FK506 and one or more other lactone compounds comprising a saturated alkyl group; dissolving the mixture in a first organic solvent to prepare a solution of the lactone compounds, wherein the first organic solvent is a water-miscible organic solvent; adding a second organic solvent, which is substantially incapable of dissolving the lactone compound FK506 and is substantially immiscible with water, to the solution of the lactone compounds to prepare a first mixed solution; adding an aqueous silver ion (Ag + ) solution to the first mixed solution so that the lactone compound FK506 dissolves into to the aqueous silver ion solution; separating at least part of the aqueous silver ion solution containing the lactone compound FK506 from the first and second organic solvents and collecting the aqueous silver ion solution; adding a third organic solvent, which is water-immiscible and capable of dissolving the lactone compound FK506, to the separated aqueous silver ion solution to form a second mixed solution containing the lactone compound FK506; and removing the silver ions from the second mixture to collect the lactone compound FK506.