A novel natural tautomeric pair of garcinielliptone FC suppressed nuclear factor κB and induced apoptosis in human colorectal cancer cells

The tautomeric pair of garcinielliptone FC (GFC) is a pure and structure-defined active ingredient, isolated from Garcinia subelliptica Merr., a plant with abundant sources of polyphenols. Here, we demonstrate that a higher concentration of GFC had no effect on normal human umbilical vein endothelial cells. On chemoresistant human colorectal cancer HT-29 cells, a time- and dosage-related cytotoxicity was observed. GFC also inhibited the nuclear expression and DNA binding activity of nuclear factor κB in a time- and dosage-related manner using Western blot and electrophoretic mobility shift assay. Furthermore, GFC induced apoptosis, which was characterized by an increase of cells at the sub-G1 phase, induction of DNA fragmentation, and formation of apoptotic bodies using flow cytometry, electrophoresis, and fluorescence microscopy, respectively. Western blot analysis revealed that both caspase-dependent intrinsic and extrinsic pathways as well as caspase-independent pathway were involved. Our data suggest the anticancer mechanisms of GFC on human colorectal cancer.