Antioxidant levels of common fruits, vegetables, and juices versus protective activity against in vitro ischemia/reperfusion.

It is well known that antioxidants present in various fruits, vegetables, and juices have the potential to protect the urinary bladder from free radical damage. What is not well understood, however, is how well antioxidant activities detected by chemical methods such as the CUPRAC assay for total antioxidant activity (TAA) predict the level of physiological protection available. It is hypothesized that the level of antioxidant reactivity found by the CUPRAC assay will positively correlate with increased protection in a model of in vitro ischemia/reperfusion. To test this hypothesis, the CUPRAC assay was utilized to determine the antioxidant reactivity of a series of fruits, vegetables, and juices, and the results were compared to the protective ability of selected juices in an established in vitro rabbit bladder model of ischemia/reperfusion. The results of the CUPRAC test showed that cranberry juice had the highest level of antioxidant reactivity, blueberry juice had an intermediate activity, and orange juice had the lowest. It was determined, however, that contrary to the hypothesis, the orange juice was significantly more potent in protecting the bladder against ischemia/reperfusion damage than either blueberry or cranberry juice. Thus, it is concluded that chemical tests for TAA do not necessarily correlate with their physiological activity.