Rapid Analysis of Curcumin and Curcumin Metabolites in Rat Biomatrices Using a Novel Ultraperformance Liquid Chromatography (UPLC) Method

The bioavailability of the putative cancer chemopreventive agent curcumin is limited, making measurement either in target tissues or in biofluids difficult and variable between studies. The purposes of these investigations were to develop validated methods of extraction of curcumin from biomatrices and of detection of curcumin and its conjugated metabolites using ultraperformance liquid chromatography (UPLC) and to identify metabolites of curcumin using online tandem mass spectrometry (MS/MS). The limit of detection for curcumin after solid-phase extraction from plasma or urine was 2.5 ng/mL. Extraction efficiencies were 62 and 64% for urine and plasma. Intra- and interday variabilities (RSD) for extraction of curcumin from biofluids were less than 10 and 15%, respectively, and accuracies were 92 +/- 10% for plasma and 95 +/- 6% for urine. Curcumin was extracted from tissues using protein precipitation with quercetin as internal standard. Curcumin extraction from intestinal mucosa spiked with 0.2, 1, and 5 mug/g curcumin was validated. Extraction efficiency was 65-84%, accuracy was 94-106%, limit of detection was 12.5 ng/g, and intra- and interday variabilitiies (RSD) were 0.7-4.9 and 4.9-5.5%, respectively. The methods were applied to measure curcumin in tissues from rats that had received oral curcumin (340 mg/kg). Curcumin was found in plasma (16.1 ng/mL), urine (2.0 ng/mL), intestinal mucosa (1.4 mg/g), liver (3671.8 ng/g), and, for the first time, kidney (206.8 ng/g) and heart (807.6 ng/g). Curcumin metabolites identified by UPLC-MS/MS in plasma and urine were phenolic glucuronides and, probably, alcoholic glucuronides. Products of reduction of curcumin and their metabolites were found in the liver. The methods described here represent improvements on existing analytical methods for curcuminoids and metabolites in terms of sensitivity, speed, and separation.