Bound polyphenol from foxtail millet bran induces apoptosis in HCT-116 cell through ROS generation

Millet bran contains an abundance of phytochemicals, among which polyphenols exhibit a wide range of pharmacological and medicinal properties. Polyphenols in millet bran are found in the free as well as bound forms and exist mainly in the bound form. Bound polyphenols in millet bran exhibit higher biological activities, including antioxidant, antitumour, immunomodulation, antifungal and anti-hyperglycaemia effects, while the underlying mechanisms of antitumour effects towards human colorectal cancer HCT-116 cells are not investigated. In this study, bound polyphenols of inner shell (BPIS) were isolated from foxtail millet bran that could inhibit the growth and induce apoptosis in human colorectal cancer HCT-116 cell and in HCT-116-bearing nude mice. Furthermore, the data implicated that the anti-colon cancer effects of BPIS were realized by promoting reactive oxygen species (ROS) generation in HCT-116 cell. Mechanistically, its pro-apoptotic activity was mainly attributed to the activation of mitochondria-mediated intrinsic pathways and the blockage of NF-κB signalling pathway of the downstream of ROS. The results indicated that millet bran-derived BPIS displayed anti-colon cancer functions though its pro-oxidant activity. It suggests that the millet bran-derived BPIS can act as a natural therapeutic agent against colon cancer.