The present study was not designed to examine the specific
cellular mechanisms whereby the phytonutrients in tart cherry
juice exert their protective effects. However, at least 3 proposed
mechanisms for the actions of anthocyanins may be relevant. For
instance, anthocyanins can work as direct free radical scavengers
through electron transferring and are effective electron donators
(22). However, anthocyanins are poorly absorbed and rapidly
cleared. Therefore, whether the anthocyanin concentration was
sufficient to act by this mechanism seems unlikely. Of more relevance may be the ability of anthocyanins to form cyanidin-
DNA complexes that resist oxidative damage (23,24). The
reduction of oxidative damage to DNA in vivo after intervention
with the tart cherry juice may be attributable to this mechanism.
Perhaps the most relevant potential mechanism whereby tart
cherry juice might convey increased resistance is the capacity of
anthocyanins to activate xenobiotic responses. Activation of nrf-
2 by a number of polyphenols increases expression of phase II
detoxifying enzymes and antioxidant enzymes (25–27), which
can directly act to eliminate free radicals and oxidatively
damaged molecules.