Pro-apoptotic activity of Tulbghia violacea extracts was evaluated in order to understand the mechanisms of action that might be related to its traditional use as anticancer medicine. Apoptosis-guided purification was used to isolate active compound whose chemical structure was solved by using spectroscopic, microanalysis and X-ray crystallography techniques. T. violacea extract kills Chinese hamster ovary cells, MCF7, and HeLa cells through the induction of apoptosis Methyl--D-glucopyranoside was identified as one of the main pro-apoptotic compounds present in T. violacea extract. This is the first time ever demonstration that T. violacea contains methyl -D-glucopyranoside, which selectively kills cancer cells through apoptosis mechanisms.