Development of Yam Dioscorin-Loaded Nanoparticles for Paracellular Transport Across Human Intestinal Caco-2 Cell Monolayers.

Dioscorins, the major storage proteins of yam tubers, exert immunomodulatory activities. To improve oral bioavailability of dioscorins in the intestine, recombinant dioscorin (rDioscorin) was coated with N,N,N-trimethyl chitosan (TMC) and tripolyphosphate (TPP), resulting in the formation of TMC-rDio-TPP nanoparticles (NPs). The loading capacity and entrapment efficiency of rDioscorin in the NPs were 26 ± 0.7% and 61 ± 1.4%, respectively. The NPs demonstrated a substantial release profile in the pH environment of the jejunum. The rDioscorin released from the NPs stimulated proliferation and phagocytosis of the macrophage RAW264.7 and activated the gene expression of IL-1β and IL-6. Incubation of the NPs in the Caco-2 cell monolayer led to a 5.2-fold increase of Papp compared with rDioscorin alone, suggesting that rDioscorin, with the assistance of TMC, can be promptly transported across the intestinal epithelia. These results demonstrate that the TMC-rDio-TPP NPs can be utilized for elucidating the immunopharmacological effects of dioscorins through oral delivery.