Anthocyanins are naturally occurring reddish pigments that abundant in fruits and vegetables. To investigate the mechanistic basis for the anti-
tumor properties of
anthocyanins, five aglycone (
cyanidin,
delphinidin,
malvidin,
pelargonidin, and
peonidin) and four glycosylated (cyanidin-3-glucoside, malvidin-3-glucoside, pelargonidin-3-glucoside and peonidin-3-glucoside)
anthocyanins were used to examine their effects on cell cycle progression and induction of apoptosis in human gastric
adenocarcinoma AGS cells. The data from cell viability assay showed that
malvidin exhibited the most potent anti-proliferation effect on AGS cells in a time- and dose-dependent manner (P<0.05). This event is accompanied the arrest of AGS cells at the G0/G1 phase by
malvidin at the tested concentrations of 0-200 microM. Cellular uptake of
anthocyanin and
anthocyanidin was confirmed by HPLC analysis and the intracellular accumulation of
malvidin (24.9+/-1.1 microM/mg
protein) was observed when treatment of AGS cells with
malvidin for 12 h. In addition, an accumulation of AGS cells in sub-G1 phase (20% and 30% increase for 100 and 200 microM of
malvidin, respectively) was observed as well as by the appearance of a fraction of cells with an aneudiploid
DNA content. The occurrence of apoptosis induced by
malvidin was confirmed by morphological and biochemical features, including apoptotic bodies formation,
caspase-3 activation and
poly(ADP-ribose) polymerase proteolysis. Furthermore, the mitochondrial membrane potential of apoptotic cells
after treatment with
malvidin was significantly lost and resulted in the elevation of Bax/Bcl-2 ratio for 1.6-fold against control for 100 microM treatment. In addition, the
malvidin treatment significantly increased the p38
kinase expression and inhibited the ERK activity, and the effects of
malvidin on
caspase-3 activation were blocked, respectively, by the ERK and p38 inhibitors. These findings suggest that growth inhibition and cytotoxicity of AGS cells by
malvidin is involved in the induction of apoptosis rather than
necrosis.