Abstract
Scope—Anthocyanins, the natural pigments in plant foods, have been associated with cancer
prevention. However, the content of anthocyanins in staple foods is typically low and the
mechanisms by which they exert anti-cancer activity is not yet fully defined.
Methods and results—We selected an anthocyanin-enriched purple-fleshed sweet potato
clone, P40, and investigated its potential anti-cancer effect in both in vitro cell culture and in vivo
animal model. In addition to a high level of total phenolics and antioxidant capacity, P40
possesses a high content of anthocyanins at 7.5 mg/g dry matter. Treatment of human colonic
SW480 cancer cells with P40 anthocyanin extracts at 0–40 μM of peonidin-3-glucoside equivalent
resulted in a dose-dependent decrease in cell number due to cytostatic arrest of cell cycle at G1
phase but not cytotoxicity. Furthermore, dietary P40 at 10–30% significantly suppressed
azoxymethane-induced formation of aberrant crypt foci in the colons of CF-1 mice in conjunction
with, at least in part, a lesser proliferative PCNA and a greater apoptotic caspase-3 expression in
the colon mucosal epithelial cells.
Conclusion—These observations, coupled with both in vitro and in vivo studies reported here,
suggest anthocyanin-enriched sweet potato P40 may protect against colorectal cancer by inducing
cell cycle arrest, anti-proliferative and apoptotic mechanisms.