Constructing Dendrobium officinale extracts-coated zein nanoparticles as oral delivery vehicles for curcumin

The aim of this study is to apply aqueous extracts of fresh Dendrobium officinale (DOE) to modify the properties of zein, and increase synergistically the activity of curcumin (Cur). DOE was prepared using a water-extraction method firstly. Then, DOE coated-zein nanoparticles (DLZ NPs) were developed by an antisolvent precipitation method. The results showed that DOE coating improved the dispersity and stability of zein NPs greatly. At a suitable DOE content, spherical DLZ NPs with small particle size (similar to 200 nm) were established. They exhibited good aqueous stability and redispersibility. Then, Cur was well encapsulated (encapsulation efficiency>98%) in DLZ NPs in an amorphous state. Compared with raw Cur, Cur/DLZ NPs had more than 3.0-fold bioaccessibility, 6.8-fold antioxidant activity and higher antitumor activity, where DOE coating played a well synergistic role. Moreover, DOE coating increased the cellular uptake of zein NPs significantly. These findings suggest that DLZ NPs are promising vehicles for the oral delivery of hydrophobic bioactive substances.