Sequential extraction of solid curcuminoids with 5% BSA. A) Solid curcuminoids in amounts of 10 mg (●), 20 mg (○), 30 mg (▼), 40 mg (▽), and 50 mg (■) were added to 1 ml of 5% BSA. After centrifugation, the supernatant containing BSA-soluble curcuminoids was removed and fresh 5% BSA was added to the remaining pellets containing insoluble curcuminoids (Methods). The procedure was repeated ten times and the concentration (μM) of total soluble curcuminoids determined. B) After the tenth extraction of solid curcumin with 5% BSA, the final pellets were washed and dissolved in 200 μl DMSO. A 10 μl aliquot of the DMSO-dissolved curcumin was added to 1 ml of 5% BSA and processed for concentration determination. The bars represent the concentration (μM) of total curcuminoids solubilized in 5% BSA. The numbers under the bars indicate the starting amount (mg) of the curcuminoids and the numbers in parentheses the final yield (mg) of DMSO-dissolved curcuminoids. C) Elution profiles of curcuminoids after first (ext.1), fifth (ext. 5), and tenth (ext. 10) extraction of 1 mg of solid curcuminoids. Also shown is the elution profile of the final pellet after ten extractions (residual) with 5% BSA. D) Same as in B, except that 50 mg of solid curcuminoids were sequentially extracted.