Abstract
Red ginseng has been used in traditional medicine for centuries in Asia. In this study, we evaluated four types of red ginseng grown in different areas (Chinese red ginseng, Korean red ginseng A, Korean red ginseng B, and Korean red ginseng C) for their ability to inhibit lung tumor formation and growth induced by the carcinogen benzo(a)pyrene (B(a)P) in A/J mice and found that Korean red ginseng B was the most effective at lowering the tumor load among the four red ginseng varieties. Moreover, we analyzed the levels of various ginsenosides (Rg1, Re, Rc, Rb2, Rb3, Rb1, Rh1, Rd, Rg3, Rh2, F1, Rk1, and Rg5) in four kinds of red ginseng extract and found that Korean red ginseng B had the highest level of ginsenoside Rg3 (G-Rg3), which suggested that G-Rg3 may play an important role in its therapeutic efficacy. This work revealed that the bioavailability of G-Rg3 was relatively poor. However, when G-Rg3 was coadministered with verapamil, a P-glycoprotein inhibitor, the G-Rg3 efflux in Caco-2 cells was lowered, the small intestinal absorption rate of G-Rg3 in the rat models was increased, the concentration levels of G-Rg3 were elevated in the intestine and plasma, and its tumor-preventive abilities in the tumorigenesis rat model induced by B(a)P were also augmented. We also found that G-Rg3 reduced B(a)P-induced cytotoxicity and DNA adduct formation in human lung cells and rescued phase II enzyme expression and activity through Nrf2 pathways, which may be the potential mechanisms underlying the inhibitory effects of G-Rg3 on lung tumorigenesis. Our study showed a potentially vital role of G-Rg3 in targeting lung tumors in murine models. The oral bioavailability of this ginsenoside was augmented by targeting P-glycoprotein, which allowed the molecule to exert its anticancer effects.