Ginsenosides 20R-Rg3 and Rg5 enriched black ginseng inhibits colorectal cancer tumor growth by activating the Akt/Bax/caspase-3 pathway and modulating gut microbiota in mice

Black ginseng (BG) is of great interest for its anti-cancer property. Its detailed mechanism, however, is still lacking. This study aims to evaluate the effectiveness of ginsenosides 20R-Rg3 and Rg5 enriched BG (Rg3/Rg5-BG), innovatively prepared by low temperature steam-heating process, against colorectal cancer (CRC), and elucidate its potential molecular mechanism. Interestingly, much higher concentrations of rare ginsenosides were detected in this unique BG than those in red ginseng, especially 20R-Rg3 and Rg5, which may contribute to treatment of CRC. As expected, Rg3/Rg5-BG demonstrated a dose-dependent reduction in cancer cell viability, along with the induction of cell apoptosis and cell cycle arrest. Moreover, Rg3/Rg5-BG retarded tumor growth in the model mice, as evidenced by downregulation of anti-apoptotic Bcl-2 protein and phosphatidyl Akt, and upregulation of the apoptotic proteins Bax, caspase-8, and cleaved caspase-3, enhancing apoptosis of tumor cells. Additionally, Rg3/Rg5-BG treatment improved the gut microbiota and intervened with bacteria associated with cancer development, including increasing beneficial probiotics such as Candidatus_Saccharibacteria and Saccharibacteria_genera_incertae_sedis and decreasing pernicious bacteria (Vampirovibrio, Clostridium_XlVb, etc.). Our results manifested for the first time that Rg3/Rg5-BG exerted its anti-cancer effects: through activation of the caspase-3/Bax/Bcl-2 pathway and by altering the gut microbiome composition, thus paving the way for new therapeutic strategies that incorporate natural products in cancer treatment.