Glycosylation of anthocyanins enhances the apoptosis of colon cancer cells by handicapping energy metabolism

Abstract

Background While anthocyanins are proven to be effective in inhibiting tumour cell proliferation, the underlying mechanisms remain unclear. This research aims to explore the glycosylation of anthocyanins in the tumour inhibitory effects and the potential mechanism. Methods The tumour inhibitory effect on mouse colon cancer cells (MC38) was examined by MTT and flow cytometric analyses. The inhibitory pathway of anthocyanin was explored by assessment of tumour cell mitochondrial membrane potential (MMP), the caspase-3 and caspase-9 activity, as well as the cell energy metabolism in terms of the glucose uptake, the NAD+/NADH ratio and the ATP level. Results We found that 500 μM bilberry anthocyanins extract (BAE) induced 48.1% mitochondrial damage, activated the downstream caspase cascade to form apoptotic bodies (caspase-3 activity increased by 169%, caspase-9 activity increased by 186%), and inhibited cell proliferation (survival rate: 55.97%, 24 h). In contrast, the same concentration of anthocyanidin (cyanidin) led to marginal mitochondrial damage (only 9.85%) and resulted in little inhibition of MC38 cells (survival rate: 86.84%, 24 h). For cells incubated with 500 μM BAE, reactive oxygen species (ROS) decreased by 53.8%, but the ratio of NAD+/NADH increased to 3.67, demonstrating that the mitochondrial damage was induced by blocking energy metabolism. Furthermore, cell energy metabolism is related to glucose uptake since the presence of 200 μM GLUT1 inhibitor substantially enhanced the inhibitory effects of cyanidin-3-O-glucoside (Cy-3-Glu) at 500 μM (survival rate: 51.08%, 24 h). Conclusions The study suggested that the glycosides of anthocyanins might handicap glucose transport and inhibit energy metabolism, which, in turn, led to mitochondrial damage and apoptosis of tumour cells.

Anthocyanins in Colorectal Cancer Prevention Review

“…Bilberry showed an antiproliferation effect in HT-19 cells and the mechanisms associated with increasing the expression of p21 [38][39][40]. Bilberry anthocyanin extract induced mitochondrial damage, activated apoptosis, inhibited cell proliferation in the mouse colon cancer cell line MC38 [41]. Bilberry extract has the potential to reduce the side effects of some chemotherapy drugs by suppressing the activity of topoisomerase I and the DNA strand breaks [42].…”

Microbial Transformation of Galangin Derivatives and Cytotoxicity Evaluation of Their Metabolites

“…These results suggested that O-glycosylation of flavonoids at the C-7 position could enhance their cytotoxic activities. Transmembrane delivery of flavonoid glycosides was reported to be carried out by glycoside binding to glucose transporters on the cell membrane [47]. Sodium-glucose cotransporter 1 and glucose transporter 2 mediated the cross-membrane transport of quercetin-3-O-glucoside and cyanidin-3-O-glucoside in Caco-2 cells [48].…”

Malvidin-3-O-Glucoside Ameliorates Cadmium-Mediated Cell Dysfunction in the Estradiol Generation of Human Granulosa Cells

“…Previous studies have shown that in a damaged cell model, anthocyanins with the monosaccharose substitution dissolved in DMSO had a significantly stronger protective effect than those with the disaccharide substitution against oxLDL-induced endothelial injury associated with increased cell viability, promoted NO release, and so on [ 21 ]. Analogously, C3 position glycosylation on anthocyanin dramatically increased its inhibitory effect on tumor cells [ 22 ]. Consistent with these observations, M3G was more effective than MV and M3,5G in reducing cytotoxicity when applied to KGN cells exposed to Cd, indicating that the monosaccharose structure has a stronger protective effect against Cd damage.…”