Epidemiological suggest that consumption of cereals, fruits and vegetables might lower the risk of cancer. Many phytochemicals have been identified for their anticancer effect. The phytochemicals belonging to the flavonoid group are known for their antioxidant and anticancer properties. Cranberries are a very rich source of these flavonoids.
Previous studies have shown that extracts from cranberry presscake, which is the leftover after pressing cranberries to produce cranberry juice, reduced the growth and metastasis of human tumor cells which were implanted in mice.
The purpose of this study was to identify the phytochemicals which are responsible for the anti-cancer effect and to determine their mechanism.
The extract from cranberry presscake was fractioned to obtain different extracts including a flavonoid rich extract. The different fractions were tested on different tumor cell lines. The flavonoid rich cranberry extract was the most active and inhibited the proliferation of many human tumor lines. The flavonoid rich cranberry extract was most effective against androgen-dependent prostate cells and least effective against estrogen-independent breast cells and androgen-independent prostate cells. Other cancer cell lines, including specific tumor lines of breast, skin, colon, lung and brain, showed intermediate reaction to the cranberry extract. Because the flavonoid rich cranberry extract had similar effect on estrogen-dependent M-C7 breast cells as well as estrogen-independent MDA-MB-435 breast cells the action of extract was not related to any anti-estrogenic action.
It is not known which specific flavonoids are responsible for the inhibition of proliferation. Other studies have shown that the flavonoids epigallocatechin gallate, catechin and epicatechin. The flavonols quercetin, myricetin and resveratrol may also contribute to the anti-proliferation action of the cranberry extract.
The study concluded that the flavonoid rich cranberry extract block cell cycle progression and induced cell apoptosis in specific tumor lines. More studies to identify the phytochemicals responsible for the cytotoxic activity of cranberry extracts could yield a new anticancer drug.
Source: Ferguson PJ, Kurowska E, Freeman DJ, Chambers AF and Koropatnick DJ. A flavonoid fraction from cranberry extract inhibits proliferation of human tumor cell lines. Journal of Nutrition, 2004 Jun;134(6):1529-35