A compound from milk thistle kept liver cancer cells from spreading and reduced their numbers in a new laboratory study. Researchers from the University of California at Irvine tested various doses of silibinin, the major constituent of silymarin (the mixture of flavonolignans extracted from blessed milk thistle), in its pure form. Doctors found that a dose of 180 micromoles per liter (mm/L) of silibinin kept liver cancer cells from spreading. At a dose of 240 mm/L, silibinin accelerated the natural death rate of cancer cells by a factor of nine times. In a major finding, scientists noted that silibinin appeared to allow cells enough time to detect and repair DNA damage before passing the bad trait onto new cells. Silibinin also decreased the abnormal blood vessels that feed tumors. Study author, Dr. Ke-Qi Hu, noted that silibinin has “novel anti-cancer mechanisms” and provides researchers with new options for preventing cancer.