Simultaneous quantification of free curcuminoids and their metabolites in equine plasma by LC-ESI-MS/MS

The human health benefits attributed to turmeric/curcumin spice has resulted in its wide utilization as a dietary supplement for companion pets and other animals including horses. While the quantification of free curcuminoids (curcumin, demethoxycurcumin, bisdemethoxycurcumin) and their phase-2 metabolites (curcumin-O-sulfate, curcumin-O-glucuronide) have been extensively investigated in human and rodent biological samples (primarily plasma and serum), there is lack of similar data for horses. Herein, we report a validated LC-ESI-MS/MS method for the simultaneous quantification of the aforementioned free curcuminoids and their metabolites in equine plasma. The linearity of the aforementioned curcuminoids and curcumin-O-sulfate was in the range of 0.5-1000 ng/mL and 1-1000 ng/mL for curcumin-O-glucuronide with 85-115% accuracy and <15% precision in equine plasma. The method was validated based on US FDA criteria and applied to characterize the pharmacokinetics of curcumin-O-sulfate in equine plasma.