Abstract
Maple syrup is a natural sweetener that is commonly consumed worldwide. While maple syrup mainly comprises sucrose, it also contains phytochemicals that present various biological effects. Maple syrup is made by boiling down sap, and its color and composition vary in accordance with the sap collection season. Typically, seasonal progression is associated with darker syrup color, and antioxidant activity is proportional to the increasingly dark color. The authors previously reported that maple syrup demonstrated inhibitory effects on colorectal cancer cell growth and invasion, which correlated with darker maple syrup color. In the present study, they examined the effects of two different grades of maple syrup on gastrointestinal cancer cell proliferation, to investigate whether the dark-color maple syrup was suitable as a phytomedicine for gastrointestinal cancer treatment. Administration of dark-color maple syrup significantly inhibited gastrointestinal cancer cell growth as compared to non-treated cancer cells. Moreover, administration of dark-color maple syrup clearly inhibited protein kinase B (AKT) phosphorylation and did not impact mitogen-associated protein kinase phosphorylation. These data suggested that dark-color maple syrup may inhibit cell proliferation through suppression of AKT activation and, thus, may be suitable as a phytomedicine for gastrointestinal cancer treatment.