Bioanalytical method by HPLC-FLD for curcumin analysis in supplemented athletes

In sports, curcumin, a substance derived from the rhizome of Curcuma longa (turmeric) plant with antioxidant effect 8 times greater than vitamin E, has attracted the attention of scientists because of its potent antioxidant action, since in athletes subjected to intense exercise the-endogenous mechanisms of neutralization of reactive species are saturated. However, the pharmacokinetic characteristics of curcumin do not favor its medicinal use due to its low absorption, accelerated metabolism and rapid systemic elimination. Thus, the determination of plasma levels in supplemented patients is a crucial step in their pharmacodynamic evaluation. Therefore, the objective of this work was to develop and validate an analytical method by HPLC-FLD for curcumin evaluation in plasma of supplemented athletes. Luna column (C18; 150 × 4 mm; 3 µm), acetonitrile: acetic acid pH 3.2 (45:55 to 60:40) as mobile phase, flow rate of 1 mL min^-1, excitation at 429/285 nm and emission at 529 nm and injection of 10 µL were the chromatographic conditions used. Plasma samples were extracted using ethylacetate and methanol (95: 5, 500 µL) and estradiol (30 µg mL^-1) as internal standard, with subsequent stirring (3 min) and centrifugation (8 min) (triple extraction). The organic fraction was evaporated under N₂ (20 min) and the dried residue reconstituted in acetonitrile. The method was linear between 44 and 261 ng mL^-1, showing intra-day (2.05.6%) and inter-day (4.0-5.1%) precision with accuracy and selectiveness (curcumin t_R = 8.7 min and internal standard t_R = 13.9 min with relative recovery of 83.2%). So, it can be successfully used for curcumin evaluation in plasma samples from supplemented athletes, as well as being an alternative and advantageous method to UV-Vis and MS/MS in bioavailability studies.