Abstract:

Cholesterol and plant phytosterols are lipophilic compds. solubilized by intestinal micelles in a competitive manner. In this work, we used radioactive cholesterol- and phytosterol-loaded oil-in-water microemulsions to follow their incorporation and mutual competition in HaCaT keratinocytes, SZ95 sebocytes, and skin pieces in cultures. Dynamic light scattering showed homogeneous nanostructures of 10.5 ± 1.5 nm diam. and cryo-transmission electron microscopy confirmed the presence of uniform spherical droplets of 7.0 ± 1.0 nm diam. Up to 320 nmol/mL of cholesterol can be solubilized and transported into cells with minimal toxic effect by 0.5 wt.% nanodroplets in a cell medium. Phytosterols inhibit incorporation of cholesterol into cells, in vitro, at molar ratios (phytosterols/cholesterol) of 4 and above. The loaded nanodroplets accumulate in intracellular vesicles (presumably endosomes). No metabolic conversion of cholesterol or phytosterols was found in these cells, in vitro, after 24 h, at 37°. [on SciFinder(R)]