Citrus fruits are economically significant crops worldwide, as they contain various bioactive compounds that possess health-promoting properties. Carotenoids, as the most important component in citrus, exhibit notable pharmacological activities, such as antioxidation and anticancer, which make carotenoids valuable in the prevention and treatment of breast cancer. In this study, after treatment with carotenoid extracts from XiYou (XY) and ZaoHongQiCheng (ZH), we evaluated the cytotoxicity, apoptosis, antioxidant system, and oxidative stress induced by ROS overproduction and MMP damage in MDA-MB-231 cells. The analysis confirmed that cell proliferation was inhibited in a concentration-dependent manner, accompanied by G0/G1 arrest and cell apoptosis. XY and ZH promoted the accumulation of ROS, decreased MMP, increased malondialdehyde (MDA) levels, consumed glutathione (GSH), and reduced the activity of antioxidant enzymes (peroxidase (POD), catalase (CAT), glutathione reductase (GR), and superoxide dismutase (SOD)). Meanwhile, XY and ZH induced apoptosis through the mitochondrial pathway by significantly upregulated P53, BAX, caspase-3, caspase-7, and caspase-9 gene expression levels and downregulated Bcl-2. Carotenoid-rich extracts were found to cause oxidative stress by enhancing ROS production through their pro-oxidative potential, and the aggravation of oxidative processes promotes apoptosis in MDA-MB-231 cells. These results indicate that citrus carotenoids can be used as potential pro-oxidants and have the potential to be developed into products for the prevention or treatment of breast cancer.
Keywords: apoptosis; carotenoids; citrus; oxidative stress; reactive oxygen species (ROS).