Endogenous Circadian Rhythms in Polyphenolic Composition Induce Changes in Antioxidant Properties in Brassica Cultivars.

There is increasing evidence that the circadian clock is a significant driver of plant phytochemicals. However, little is known about the clock effect on antioxidant metabolites in edible crops. Thus, the aim of the present investigation was to study whether the antioxidant potential of Brassica cultivars is under circadian regulation and its relationship with polyphenol content. To accomplish that we entrain plants of four Brassica cultivars to light-dark cycles prior to release into continuous light. The antioxidant activity and phenolic content was monitored at four time points of the day during four consecutive days: 2 days under light-dark conditions followed by 2 days under continuous light. Results showed daily oscillation of antioxidant activity. In addition, those variations were related with endogenous circadian rhythms in polyphenolics and exhibit a species-specific pattern. Considered together, we determined that Brassica cultivars have an optimal time during a single day with increased levels of health phytochemicals.