Encapsulation of indole-3-carbinol and 3,3'-diindolylmethane in zein/carboxymethyl chitosan nanoparticles with controlled release property and improved stability.

Indole-3-carbinol (I3C) and 3,3'-diindolylmethane (DIM) are two bioactive compounds from Cruciferous vegetables. The stability of these compounds is a major challenge for their pharmaceutical applications. In this study, zein and zein/carboxymethyl chitosan (CMCS) nanoparticles were prepared to encapsulate I3C and DIM by a combined liquid-liquid phase separation and ionic gelation method. After zein nanoparticles were coated with CMCS, the zeta potential was decreased from around -10 to -20 mV, and encapsulation efficiency was greatly improved. Both nanoparticle formulations provided controlled release of I3C and DIM in PBS medium. Zein and zein/CMCS nanoparticles demonstrated similar protection for both I3C and DIM against ultraviolet (UV) light, attributed mainly to the contribution of the zein protein. Compared with zein nanoparticles, zein/CMCS nanoparticles exhibited better protection of I3C against degradation and better inhibition against its oligomerization to DIM under thermal condition (37°C). Based on our results, the encapsulation of hydrophobic bioactives in zein/CMCS nanoparticles is a promising approach to improve their stability against harsh conditions and provide controlled release for food/pharmaceutical applications.