Tea bioactive compounds especially polyphenols are known to possess healthy functions. However, the poor bioavailability of polyphenols hinders their biological effects. Several investigators have been found that the bioavailability of tea polyphenols is enhanced when co-administered with food matrices or ingredients. In the present study, we investigate whether the bioavailability of tea polyphenols is affected with other bioactive compounds in tea such as caffeine and free amino acids in the intestinal Caco-2 monolayer cell model. We confirmed that epigallocatechin gallate (EGCG), epicatechin gallate (ECG) and theaflavin-3,3’-digallate (TFDG) are the active efflux way, while caffeine and theanine are passive diffusion in Caco-2 cell model. When EGCG co-transported with theanine, serine and glycine respectively, all of its transport way were changed from active efflux to passive diffusion. Similarly, TFDG transport way was changed to the passive diffusion with co-administration of caffeine. However, TFDG cannot be detected in the transported side of Caco-2 monolayer cells when co-incubated with theanine. Theanine, serine or glycine can improve the bioavailability of ECG through the passive diffusion while caffeine does not. The result from the molecular docking shows that caffeine has competitive capacity with TFDG on the binding to the efflux protein multi-resistance protein 1 (MRP1) and P-glycoprotein (PgP) to decrease the efflux of TFDG. In conclusion, the co-existed compounds in tea could influence the bioavailability of polyphenols. The mechanism needs to be clarified in future.

Caffeine and amino acids affect the bioavailability of tea polyphenols in human Caco-2 intestinal cells

256th National Meeting (2018)

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