Identification of cinnamaldehyde as most effective fatty acid uptake reducing cinnamon-derived compound in differentiated Caco-2 cells compared to its structural analogs cinnamyl alcohol, cinnamic acid and cinnamyl isobutyrate.

Naturally occurring cinnamon compounds like cinnamaldehyde (CAL) and structurally related constituents have been associated with anti-obesity activities, although studies regarding the impact on intestinal fatty acid uptake are scarce. Here, we demonstrate effects of CAL and structural analogues cinnamyl alcohol (CALC), CAC (cinnamic acid) and cinnamyl isobutyrate (CIB) on mechanisms regulating intestinal fatty acid uptake in differentiated Caco-2 cells. CAL, CALC and CAC (3000 µM) were found to decrease fatty acid uptake by 58.0 ± 8.83 %, 19.4 ± 8.98 % and 21.9 ± 6.55 %, respectively. Whereas CAL and CALC at a concentration of 300 µM increased serotonin release 14.9 ± 3.00- and 2.72 ± 0.69-fold, respectively, serotonin itself showed no effect on fatty acid uptake. However, CAL revealed transient receptor potential channel A1 (TRPA1)-dependency in the decrease of fatty acid uptake, as well as in CAL-induced serotonin release. Overall, CAL was identified as most potent of the cinnamon constituents tested.