HPLC Analysis of Curcuminoids in Dietary Supplements and in vitro Digestion Fractions

Abstract

Curcumin (Cur), demethoxycurcumin (DMC), and bis‐demethoxycurcumin (BDMC) are the main curcuminoids in Curcuma longa used to prepare the spice turmeric. Cur has been shown to reduce the risk of cancer, inflammation and Alzheimers. As such, it has become increasingly popular in foods and dietary supplements. To examine content and bioaccessibility of commercial Cur products, we developed and validated an HPLC method to measure Cur and metabolites. Dietary supplements were processed via an in vitro digestion (simulated gastric and small intestinal phases) and Caco‐2 cellular uptake (Chitchumroonchokchai et al., J. Nutr. 2004). Cur, DMC, BDMC were monitored at 425nm for sensitive detection and 280nm was monitored to detect the internal standard, Flavone, and cellular metabolites of curcuminoids. Three products were tested containing from 10% to 95% curcuminoids. The micellarized Cur was stable in cell culture medium for at least 4 hrs. Transfer of Cur from the supplements to micelles during the small intestinal phase of digestion varied markedly between the two products. Micellarization was more efficient as polarity increased, i.e., BDMC> DMC>Cur. Efficiency (%) of incorporation into micelles was higher for Curcu‐Gel™ than Turm’Brite 10% sd Cur, 29.1% vs 8.7%. Cur in synthetic micelles was taken up by the cells in a time and concentration dependent manner. (Supported in part by Tishcon Corp., Westbury, NY)