The aim of this study is to construct a pH- and reduction-responsive nanodrug delivery system to effectively deliver a ginsenoside (Rh2) and enhance its cytotoxicity against human hepatocarcinoma cells (HepG2). Here, pullulan polysaccharide was grafted by urocanic acid and α-lipoic acid (α-LA) to obtain a copolymer, α-LA-conjugated N-urocanyl pullulan (LA-URPA), which was expected to have pH and redox dual response. Then, the copolymer LA-URPA was used to encapsulate ginsenoside Rh2 to form Rh2 nanoparticles (Rh2 NPs). The results showed that Rh2 NPs exhibited an average size of 119.87 nm with a uniform spherical morphology. Of note, Rh2 NPs showed a high encapsulation efficiency of 86.00%. Moreover, Rh2 NPs possessed excellent pH/reduction dual-responsive drug release under acidic conditions (pH 5.5) and glutathione (GSH) stimulation with a low drug leakage of 14.8% within 96 h. Furthermore, Rh2 NPs with pH/reduction dual response had higher cytotoxicity than Rh2 after incubation with HepG2 cells for 72 h, indicating that Rh2 NPs had a longer circulation time. After the treatment with Rh2 NPs, the excessive increase of reactive oxygen species and the decrease of superoxide dismutase, glutathione (GSH), and mitochondrial membrane potential suggested that the mitochondrial pathway mediated by oxidative stress played a role in this Rh2 NP-induced apoptosis. In conclusion, this study provides a new strategy for improving the application of ginsenoside Rh2 in the food and pharmaceutical fields.
Keywords: bioavailability; ginsenoside Rh2; hepatocellular carcinoma (HCC); nanoparticles; pH and reduction dual response.