Stability studies of pure and mixture form of curcuminoids by reverse phase-HPLC method under various experimental stress conditions

Since time immemorial, turmeric has been widely marketed and consumed as dietary supplement due to its diverse medicinal properties. Curcuminoids-comprising a mixture of curcumin (CUR), demethoxycurcumin (DMC), and bisdemethoxycurcumin (BDMC)-are the prime bioactive constituents of turmeric. However, the usage of curcuminoids is limited by their chemical instability. The lack of information on comparative stability profiles of curcuminoids (in pure and mixture form) prompted us to study how pure curcuminoids and their mixtures behave under different stress degradation conditions. The order of stability of curcuminoids when exposed to acidic, alkaline, and oxidative degradation was found to be as follows: BDMC > DMC > CUR. While the pure and mixture forms of curcuminoids were stable against heat, they completely degraded upon exposure to sunlight. The degradation extent of curcuminoids (in mixture form) was substantially less as compared to their pure form; therefore, this suggested the synergistic stabilizing influence of DMC and BDMC in the curcuminoids' mixture.