Melatonin levels, determined by LC-ESI-MS/MS, fluctuate during the day/night cycle in Vitis vinifera cv Malbec: Evidence of its antioxidant role in fruits.

BOCCALANDRO, HERNÁN ESTEBAN; GONZALEZ, CARINA VERONICA; WUNDERLIN, DANIEL A; SILVA, MARÍA FERNANDA

JOURNAL OF PINEAL RESEARCH

WILEY-BLACKWELL PUBLISHING, INC

Año: 2011 vol. 51 p. 226 - 232

0742-3098

The identification of melatonin in plants has inspired newinvestigations to understand its biological function and which endogenousand external factors control its levels in these organisms. Owing to thetherapeutical and nutraceutical properties of melatonin, it should beimportant to develop reliable analytical methods for its quantification invegetal matrices containing this indoleamine, such as grape and wine. Themain objectives of the present study were to test whether melatonin levelsfluctuate during the day in berry skins of Vitis vinifera L. cv Malbec, therebypossibly relating its abundance to its putative antioxidant function, todetermine whether daylight reaching clusters negatively controls melatoninlevels, and to evaluate whether total polyphenols and anthocyanins alsochange through a 24-hr period. Grapes were harvested throughout the day/night to determine the moment when high levels of these components arepresent in grapes. The presence of melatonin in grapes was evaluated byhigh-performance liquid chromatography/electrospray ionization tandemmass spectrometry. It is shown for the first time that melatonin levelsfluctuate during the day/night cycle in plants grown under field conditions ina fruit organ of the species Vitis vinifera. We also determined that the diurnaldecay of melatonin in berry skins is induced by sunlight, because coveredbunches retained higher melatonin levels than exposed ones, thus explainingat least part of the basis of its daily fluctuation. Evidence of melatonin and itsantioxidant role in grapes is also suggested by monitoring malondialdehydelevels during the day.