In the present study, the colonic metabolism of three curcuminoids (80.1% curcumin, 15.6%, demethoxycurcumin (DMC) and 2.6% bis-demethoxycurcumin (Bis-DMC)) was evaluated using an in vitro model containing human faecal starters. The breakdown products formed were identified and characterized using different analytical platforms. Following in vitro incubation, the relative amounts of degraded curcuminoids and the produced metabolites were analyzed using a UHPLC coupled with a linear ion trap mass spectrometer, with the addition of hybrid ion trap-Orbitrap Mass Spectrometer when required. Up to ∼24% of curcumin, ∼61% of demethoxycurcumin (DMC) and ∼87% of bis-demethoxycurcumin (Bis-DMC) were degraded by the human faecal microbiota after 24 h of fermentation in vitro. Three main metabolites, namely tetrahydrocurcumin (THC), dihydroferulic acid (DFA) and a metabolite with an accurate mass of 181.08734, which was tentatively identified as 1-(4-Hydroxy-3-methoxyphenyl)-2-propanol were detected in the fermentation cultures containing the curcuminoids. The data presented here provide insights into curcuminoid colonic metabolism, showing that bacterial breakdown products should be considered in further studies on both bioavailability bioactivity of curcumin.
Keywords: Curcumin; curcuminoids; faecal slurry; gut microbiota; metabolism.