An in vitro study of oral bioavailability of lupin stabilized nanocarriers for curcumin

In this study, the bioaccessibility and bioavailability of curcumin encapsulated into different lupin protein isolate-based carriers was evaluated by coupling an in vitro gastrointestinal digestion (INFOGEST) with an in vitro co-culture absorption model, Caco-2/HT29-MTX, consisting of both absorptive and mucus producing cells. A targeted ultrahigh-performance quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) method was applied to monitor the fate of curcumin post digestion and absorption, specifically analyzing the apical, cellular, and basolateral fractions. Lupin protein nanoparticles, obtained by desolvation, protected curcumin from degradation better than oil in water (O/W) emulsions stabilized with lupin protein isolate. A recovery of 70 % of initial curcumin was found in the whole digesta of nanoparticles, whereas the emulsion systems displayed ≤35 % recovery. Interestingly, unlike in the case of emulsions, where curcumin was found in the micellar phase, most of the curcumin in the digesta of nanoparticles was recovered in the insoluble phase, highlighting the influence of the matrix structure in ensuring bioaccessibility of bioactive components. Regardless of the treatment, curcumin was not detected in the basolateral compartment, after absorption and transport through the in vitro cell monolayer model. However, a noteworthy proportion of curcumin, 54 % for protein nanoparticles and ≤ 24 % for emulsions, was retrieved within the cell monolayer. Non-targeted metabolomics analysis revealed the presence of a range of curcumin metabolites in the basolateral fraction and showed distinct profiles depending on the type (structure) of the delivery systems. The study highlights the critical need for thorough research into the behavior of bioactive compounds within the gut and emphasizes the necessity for future studies aimed at gaining a deeper understanding of the impact of the food matrix. Such insights are vital for enhancing and optimizing the delivery of bioactive compounds from complex food sources.