Countercurrent purification of the tetrahydro iso-α acids derived from Humulus lupulus L

Recent biological research has shown that commercially available tetrahydro iso‐α acid (THIAA) extract exhibits a significant anti‐inflammatory response in cellular assays. To further elucidate the mechanism of the response, a method was developed and optimized for the purification of three THIAA cis congeners that are found in commercially available modified hop (Humulus lupulus L.) extracts. Utilizing a Pharmatech Research hydrodynamic countercurrent separation instrument, the choice of solvent, pH and buffer composition were optimized to increase the overall efficiency. It was determined that a quaternary HEMWat (7:3:5:5, pH 5.3) solvent system is optimal for separating cis and trans diastereomers, whereas the binary solvent system of hexanes and aqueous buffer (1:1, pH 6.8) is optimal for the isolation of individual congeners. The optimal countercurrent separation method allows for sample loadings of 3 mg of sample per milliliter of column volume, minimal purification times (1–4 h) and greater than 90% homogeneity of individual THIAA congeners.