Since the compositions and content of triterpenoids in the reported extracts were not specified, the molecular mechanism responsible for the cytotoxic effects of triterpenoids from Ganoderma lucidum is likely cell specific and dependent on chemical structures. This is evident by the different bioactive response obtained from fraction 2, which contained triterpenoids that all have an oxyl or hydroxyl group at position C23, and fraction 3, which contained identified triterpenoids that did not have any functional groups at C23. Both extracts exhibited cytotoxicity but varied in apoptotic response. The side chain variability of triterpenoids is likely to be responsible for these distinct cell cyto-activities. A structure-activity relationship study in multiple cell lines will add to the understanding of behavior of triterpenoids from Ganoderma lucidum in cancer cell models. Interestingly, an unknown compound possibly a triterpenoid was found to be one of the major components in fraction 3. Further isolation and purification are underway to identify the exact chemical structure of this unknown compound. The quantification of triterpenoids in the extract is challenging due to the unavailability of commercial standards and variability in maximum absorbance wavelengths of triterpenoids. Nevertheless, this study was the first to show the induction of apoptosis from specific set of triterpenoids in cultured human colon carcinoma Caco-2 cells. The findings may contribute to the understanding of the diverse pharmaceutical properties of Ganoderma lucidum triterpenoids as chemo-preventative agents that is dependent on the chemical structure