Chitosan nanoparticles enhance the intestinal absorption of the green tea catechins (+)-catechin and (−)-epigallocatechin gallate

Catechins found in green tea have received considerable attention due to their favourable biological properties which include cardioprotective, neuroprotective and anti-cancer effects. However, their therapeutic potential is limited by their low oral bioavailability, attributed to poor stability and intestinal absorption. We encapsulated (+)-catechin (C) and (−)-epigallocatechin gallate (EGCg) in chitosan nanoparticles (CS NP) as a means of enhancing their intestinal absorption. Using excised mouse jejunum in Ussing chambers, encapsulation significantly enhanced (p < 0.05) intestinal absorption. The cumulative amounts transported after encapsulation were significantly higher (p < 0.05), i.e. 302.1 ± 46.1 vs 206.8 ± 12.6 ng/cm2 and 102.7 ± 12.4 vs 57.9 ± 7.9 ng/cm2 for C and EGCg, respectively. The mechanism by which absorption was enhanced was not through an effect of CS NPs on intestinal paracellular or passive transcellular transport processes (as shown by transport of 14C-mannitol and 3H-propranolol) or an effect on efflux proteins (as shown by transport of 3H-digoxin) but was likely due to stabilization of catechins after encapsulation (99.7 ± 0.7 vs 94.9 ± 3.8% and 56.9 ± 3.0 vs 1.3 ± 1.7% of the initial C and EGCg concentration remaining, respectively). This study demonstrates that encapsulation of catechins in CS NPs enhances their intestinal absorption and is a promising strategy for improving their bioavailability.