Monitoring and kinetic modeling of curcumin diffusion into oleosomes

Understanding the diffusion process of hydrophobic molecules through natural phospholipid (half-)membranes is of great importance, as it occurs within organisms and therefore, offers potential applications in encapsulation in natural carriers. One illustrative case involves oleosomes, lipid droplets found in eukaryotic cells, which possess a phospholipid-protein monolayer facilitating the incorporation of lipophilic compounds into their inner core. Our approach entailed the development of a mathematical model to elucidate the diffusion of a lipophilic molecule, specifically curcumin, into oleosomes. In this model, oleosomes were represented as multilayer spheres with position-dependent diffusion and partition coefficients. We derived the model parameters through experimental techniques and stablished empirical equations. The model showed that 80% of curcumin reached the oil core while 20% stayed within the membrane (phospholipid heads and tails). Beyond its application to oleosomes and curcumin, the model presented herein holds broad application for describing the encapsulation of various lipophilic molecules into carriers featuring phospholipid (half-)membranes.