Controlled in vitro release of CBD from oleosomes via modulation of their membrane density

Oleosomes, native lipid droplets abundant in the plant kingdom, especially in oilseeds, can be extracted in simple steps and have been suggested as lipid carriers or natural substitutes for oil droplets in emulsion-like products for foods, cosmetics and pharmaceuticals. Oleosomes are good candidates as lipid carriers via the oral route due to their limited hydrolysis during gastric digestion and slow hydrolysis in the small intestinal phase. The factors that affect oleosomes' ability to resist in vitro digestion, particularly the influence of their membrane molecular composition and density, remain unknown. Therefore, oleosome lipid hydrolysis was investigated in a model of small intestinal digestion and compared with oil droplets stabilized by whey proteins and/or phospholipids and with oleosomes having lower membrane density. To showcase that the lipid hydrolysis rate can also affect cargo release, oleosomes were loaded with cannabidiol (CBD) and the CBD release was tracked. Oleosomes exhibited significantly slower lipid digestion than the droplets stabilised by whey proteins and/or phospholipids, which were rapidly digested. The low lipid hydrolysis of oleosomes during intestinal digestion has been attributed to the unique structure of the oleosome membrane proteins, oleosins, which have a long amphipathic helix pinned into the oleosome oil core and out of reach for bile salts and enzymes. Oleosomes with lower membrane density exhibited faster lipid hydrolysis, probably because the digestive enzymes could better adsorb on the interface to access the core lipids. The results elucidate the factors that affect the lipid digestion of oleosomes and demonstrate the dynamic nature of oleosomes for the controlled release of lipophilic cargos, such as CBD, in the intestinal tract.