Stability, bioavailability, and cellular antioxidant activity of piperine complexed with cyclic glucans

Piperine, the primary bioactive compound in black pepper, was complexed with cyclic glucans, including cycloamylose (CA), α-cyclodextrin, and 2-hydroxypropyl-β-cyclodextrin, to investigate the complexation effects on its solubility, stability, bioavailability, and cellular antioxidant activity (CAA). The formation of inclusion complex (IC) significantly improved the phase solubility of piperine and enhanced its stability under ultraviolet light, heat, and acidic conditions. Additionally, IC increased the retention rate of piperine after in vitro digestion. Permeability analysis using a Caco-2 cell monolayer showed that IC samples, particularly CAIC, reduced the efflux ratio compared to free piperine by decreasing the apparent permeability coefficient from apical-to-basolateral (P_{app (B-A)}). Moreover, the enhanced cellular uptake capacity of piperine in IC contributed to a marked improvement in its CAA, CAIC showing the most pronounced effect. Therefore, inclusion complexation with cyclic glucans, especially CA, can be a practical strategy to overcome the lower solubility and bioavailability of free piperine in various industrial applications.