Prediction of Permeation and Cellular Transport of Silybum marianum Extract Formulated in a Nanoemulsion by Using PAMPA and Caco-2 Cell Models.

The present study explores the potential of nanoemulsion, a lipid drug delivery system, to improve solubility and oral absorption of Silybum marianum extract. The optimized formulation contained 40 mg/mL of commercial extract (4% w/w) and it was composed of 2.5 g labrasol (20%) as the oil phase, 1.5 g cremophor EL as the surfactant, and 1 g labrafil as the cosurfactant (mixture surfactant/cosurfactant, 20%). The system was characterized by dynamic light scattering, transmission electron microscopy, and HPLC‑DAD analyses in order to evaluate size, homogeneity, morphology, and encapsulation efficiency. Physical and chemical stabilities were assessed during 40 days at 4°C and 3 months at 25°C. Stability in simulated gastric fluid followed by simulated intestinal conditions was also considered. In vitro permeation studies were performed to determine the suitability of the prepared nanoemulsion for oral delivery. Different models such as the parallel artificial membrane permeability assay and Caco-2 cell lines were applied. The nanoemulsion showed a good solubilizing effect of the extract, with a pronounced action also on its permeability, in respect to a saturated aqueous solution. The Caco-2 test confirmed the parallel artificial membrane permeability assay results and they revealed the suitability of the prepared nanoemulsion for oral delivery.