Preparative isolation of a cytotoxic principle of a forest mushroom Suillus luteus by sodium dodecyl sulfate based "salting-in" countercurrent chromatography. 
In the course of screening new anticancer natural products, an edible forest mushroom Suillus luteus (L. Ex Franch).  Gray was found to have potent cytotoxicity against several human cancer cells.  However, the lipophilic sample made some countercurrent chromatography solvent systems emulsify, which caused difficulties in the separation of its cytotoxic components.  Here, we found that the addition of an organic salt sodium dodecyl sulfate could efficiently shorten the settling time of the mushroom sample solutions by eliminating the emulsification of two-phase solvent systems.  Moreover, we found that sodium dodecyl sulfate could play a new "salting-in" role and made the partition coefficients of the solutes decrease with the increased concentrations.  Thus, a sodium dodecyl sulfate based salting-in countercurrent chromatography method has been successfully established for the first time for preparative isolation of a cytotoxic principle of the mushroom.  The active component was identified as isosuillin.  Whole results indicated that sodium dodecyl sulfate could be used as an efficient salting-in reagent for two-phase solvent system selection and targeted countercurrent chromatography isolation.  It is very useful for current natural products isolation and drug discovery.