Lycopene (LYC) has been correlated with the reduction of certain cancers and chronic diseases. However, the existence and biofunctionality of degraded, oxidized, and biotransformed LYC products in vivo have not been revealed. Therefore, this study aimed to screen and elucidate the potential bioactive lycopene-derived products in breast-cancer and non-cancerous cells. LYC-oxidation or -cleavage products were generated using KMnO4. These oxidation products were separated as fractions I-III by silica column chromatography using gradient solvent systems. Further, LC-MS/MS (ESI)+ was used to elucidate their possible fragmentation patterns and structures. Fraction II showed higher cytotoxicity (IC50 value of 64.5 μM), cellular uptake, and apoptosis-inducing activity in MCF-7 cells. This fraction consists of major peak m/ z 323, identified as apo-8,6'-carotendial. The cytotoxicity-inducing activity may be due to partial ROS generation with mitochondrial dysfunction. Further, the role of apo-8,6'-carotendial in the induction of apoptosis is demonstrated for the first time. These results illustrated that LYC-oxidation derivatives or metabolites are involved in growth inhibition of cancer cells. Exploration of specific oxidized-carotenoid products will give further insight into the field of nutritional biochemistry.
Keywords: apoptosis; breast cancer; lycopene-oxidation products; mitochondrial membrane potential; reactive oxygen species.