Nanoencapsulation of Capsaicin Attenuates the Cytotoxic Effect on Caco-2 Cells

Capsaicin is used for the treatment of a wide range of diseases like chronic pain, obesity and urinary track disorders due to its various biological activities. However, the application of capsaicin is not always feasible due to its pungency, toxicity at high doses, and low water solubility. To attenuate the adverse effects, while exploiting the beneficial properties, encapsulation of capsaicin could seem reasonable. To this end, we prepared colloidal nanosystems comprised by a surfactant stabilized oily core and coated with chitosan (Heppe 70/5, HMC⁺ GmbH - Halle/Saale, Germany, Mw: 7600 Da, DA: 32.4%; 0.5 mg/ml in 5% stoichiometric excess of 5 M HCl). These systems were loaded with capsaicin and its analogue compound nonivamide. The average hydrodynamic diameter of the formulations ranged from 188±16 to 252±27 nm. The zeta potential of all the formulations was highly positive (∼ +40 mV). Both compounds showed a drastic reduction of cell viability of Caco-2 at doses higher than 300 µM. In case of nonivamide also at lower concentrations a significant decrease of cell viability was observed. These results correlate well with the findings of our previous study with MDCK-C7 cells where 300 µM was also the threshold concentration for a strong reduction of cell viability. This study confirmed that encapsulation of both vanilloid compounds had a cytoprotective effect on Caco-2 cells.