Design of chitosan colon delivery micro/nano particles for an Achillea millefolium extract with antiproliferative activity against colorectal cancer cells.

In this study, chitosan low molecular weight (LCH) and chitosan medium molecular weight (MCH) were employed to encapsulate a yarrow extract rich in chlorogenic acid and dicaffeoylquinic acids (DCQAs) that showed antiproliferative activity against colon adenocarcinoma cells. The design of CH micro/nanoparticles to increase the extract colon delivery was carried out by using two different techniques: ionic gelation and spray drying. Ionic gelation nanoparticles obtained were smaller and presented higher yields values than spray-drying microparticles, but spray-drying microparticles showed the best performance in terms of encapsulation efficiency (EE) (> 94%), also allowing the inclusion of a higher quantity of extract. Spray-drying microparticles designed using LCH with an LCH:extract ratio of 6:1 (1.25 mg/mL) showed a mean diameter of 1.31 ± 0.21 µm and EE values > 93%, for all phenolic compounds studied. The release profile of phenolic compounds included in this formulation, at gastrointestinal pHs (2 and 7.4), showed for most of them a small initial release, followed by an increase at 1 h, with a constant release up to 3 h. Chlorogenic acid presented the higher release values at 3 h (56.91% at pH 2; 44.45% at pH 7.4). DCQAs release at 3 h ranged between 9.01- 40.73%, being higher for 1,5- and 3,4-DCQAs. After gastrointestinal digestion, 67.65% of chlorogenic and most DCQAs remained encapsulated. Therefore, spray-drying microparticles can be proposed as a promising vehicle to increase the colon delivery of yarrow phenolics compounds (mainly chlorogenic acid and DCQAs) previously described as potential agents against colorectal cancer.