An in vivo test of the biologically relevant roles of carotenoids as antioxidants in animals

Abstract

Carotenoids are well known for their contribution to the vibrant coloration of many animals and have been hypothesized to be important antioxidants. Surprisingly few examples of carotenoids acting as biologically relevant antioxidants in vivo exist, in part because experimental designs often employ carotenoid doses at levels that are rarely observed in nature. Here, we used an approach that reduces carotenoid content from wild-type levels to test for the effect of carotenoids as protectants against an oxidative challenge. We used the marine copepod Tigriopus californicus reared on a carotenoid-free or a carotenoid-restored diet of nutritional yeast and then exposed them to a pro-oxidant. We found that carotenoiddeficient copepods not only accumulated more damage but alsowere more likely to die during an oxidative challenge than carotenoidrestored copepods. We suggest that carotenoid reduction, and not supplementation, better tests the proposed roles of carotenoids in other physiological functions in animals.