Comparison of the inhibition on cellular 22-NBD-cholesterol accumulation and transportation of monomeric catechins and their corresponding A-type dimers in Caco-2 cell monolayers

- The tested compounds inhibit 22-NBD-cholesterol cellular accumulation via suppression of NPC1L1 expression.
- A-type ECG and EGCG dimers inhibited cholesterol accumulation at low transport ratios.
- Both paracellular and transcellular pathways were involved in the transportation of the tested compounds.

The hypocholesterolaemic activities of EC, ECG, EGCG and their corresponding A-type dimers (A-type EC, ECG and EGCG dimers) were investigated in Caco-2 cell monolayer model. Among them, A-type ECG and EGCG dimers are the unique units of persimmon proanthocyanidins and few information about their bioavailability is available. The data showed that all of these six phenols could inhibit fluorescent 22-NBD-cholesterol cellular accumulation significantly (P < 0.01) through suppression of NPC1L1 gene expression which is related with cholesterol absorption. The further data demonstrated that the cholesterol-lowering activities of the six compounds were also involved with their chemical structures and permeability in Caco-2 monolayers. Additionally, we found that all of the tested compounds were the substrates of P-gp and tight junctions could limit the bioavailability of these compounds. These are also the first data concerning the permeability of A-type ECG and EGCG dimers across Caco-2 cell monolayer.