Phytoglycogen to increase lutein solubility and its permeation through Caco-2 monolayer

- Lutein (LT) was combined with phytoglycogen (PG) to form PG-LT complexes.
- With PG, LT was solubilized to up to 130.65 μg/mL.
- PG-LT complexes showed negligible crystallinity.
- PG-LT complex greatly improved Caco-2 transepithelial permeation of LT.

Increasing the solubility of poorly water-soluble bioactives is essential to enhancing their bioavailability. The objective of this study was to evaluate the impact of phytoglycogen (PG) on water solubility of lutein and its transepithelial permeation across Caco-2 cell monolayers. Solid PG-LT complexes were prepared by combining an acetone solution of LT with an aqueous solution of PG under sonication, followed by centrifugation and vacuum drying of the supernatant as well as a further purification procedure. X-ray powder diffraction and differential scanning calorimetry showed negligible crystalline structure of LT in the PG-LT complex tested. The maximal water solubility of LT (130.65 μg/mL) occurred at the PG/LT combination ratio of 53.3/1, which was significantly higher than that of LT alone (0.56 μg/mL). Remarkably, LT, when complexed with PG, exhibited much-enhanced permeation through Caco-2 monolayer than LT alone, suggesting a potential role of PG to improve LT bioavailability. This study indicated that PG could be applied for the delivery of LT and possibly other hydrophobic ingredients.

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