All compounds synthesized from silybin and madecassic acid were initially screened for their antiproliferative activity on the HepG2 cell line using the MTT assay before testing on other hepatocarcinoma cell lines. As shown in Table , the GI50 values for the 18 compounds on HepG2 cells was diverse. A number of compounds showed a significantly higher antiproliferative activity on HepG2 versus the original compounds silybin (1) and madecassic acid (2), whilst others exhibited weaker activity. To illustrate, compounds 3, 8, 11 and 14 showed lower GI50 values and therefore improved antiproliferative activity in comparison to that of the two original compounds silybin and madecassic acid (2) and notably neither 3 nor 14 contain a silybin unit. In contrast, compounds 4, 5, 7, 10, 12, 16 and 18 showed reduced antiproliferative activity (higher GI50 values), versus the two starting compounds and 4 and 5 (conjugated to silybin's 7-position) had GI50 values greater than 500 µM. The other group including compounds 6, 9, 13, 15, 17 presented improved antiproliferative activity versus silybin, but not madecassic acid.