In vitro bioaccessibility of lutein diesters in relation to their chemical structure

This study investigated the bioaccessibility of ten synthetic lutein diesters using the in vitro INFOGEST human digestion model, enabling comparative evaluation of their digestive behavior under controlled food-matrix conditions. We revealed that lutein ester chain length was the primary determinant of bioaccessibility, while branching influenced the extent of hydrolysis. Linear short-chain diesters demonstrated superior bioaccessibility (6.7-18.9%). Branched and bulky derivatives, surprisingly, achieved comparable bioaccessibility (6.6-8.3%) despite high hydrolytic resistance, suggesting mechanisms beyond simple ester cleavage. Conversely, long-chain lutein diesters (> C10), prevalent in commercial supplements, exhibited poor micellization, limited hydrolysis, and consequently very low bioaccessibility (<3%). Finally, two pharmaceutical formulations of the lead lutein diester, lutein di(2,2-dimethylpropanoate), were developed: a sunflower oil formulation and a liquisolid formulation utilizing a porous aluminometasilicate carrier. The sunflower oil formulation enabled significantly higher pigment stability and bioaccessibility, highlighting its superior potential for effective lutein delivery in novel food and pharmaceutical applications.