LETTER TO THE EDITOR

Melatonin in grape, not just a myth, maybe a panacea

To the EditorIn 2006, the detection of melatonin in different grape

cultivars was published with the questioning title �Melato-nin content in grape: myth or panacea?� [1]. This discoverywas the result of an ongoing series of studies on the ability

of agrochemicals to elicit the synthesis of phytoalexins inplants. Phytoalexins (from Greek alexein, to ward off) areplant secondary metabolites with a broad spectrum biolog-ical activity, whose biosynthesis represents an active plant

defence response against both biotic and abiotic stresses.However, the physiological and pathophysiological func-tion of melatonin in plants is still unclear, though a

hormone-like role has been putatively attributed to mela-tonin in some plant species [2–4]. Anyway, many phyto-alexins, such as resveratrol, are powerful bioactive

phytochemical constituents of plant-derived functionalfoods and beverages, also named dietary therapeutics ornutraceuticals. In turn, a functional food or beverage is aproduct consumed as part of a normal diet that may

provide health benefits beyond basic nutritional functions,by virtue of its nutraceutical content [5].

Since the publication, an intense media coverage ensued,

as documented by the number of newspapers, magazinesand websites reporting the finding. However, after theinitial excitement, from an academic point of view, the main

goal of the scientific community was that of ascertaining ifmelatonin in grape can be extracted during fermentationand retained in wine, as attested by two excellent papers

very recently published on this topic. Marcolini et al. [6]reported an original analytical method for the determina-tion of resveratrol and melatonin in wine based on HPLCcoupled to fluorescence detection [6]. Almost contempora-

neously, Guerrero et al. [7] investigated the presence ofmelatonin in wine; they showed that, in humans, serummelatonin concentration was significantly increased after

wine intake (1 hr after a single 100-mL wine administra-tion). In this work, the melatonin concentration detected inSpanish wines ranged from 50 to 80 pg/mL, whereas, in

Italian wines, it ranged around 0.4–0.5 ng/mL [6, 7].Noticeably, cultivar, agro-meteorological conditions [8],vintage and wine-making procedures presumably contrib-

ute to the above reported differences. Interestingly, inItalian grape cultivars, melatonin content ranged 0.005–0.96 ng/g or 2.5–428 pg/mL, and open field treatments,with a functional analogue of the plant hormone salicylic

acid, greatly enhanced melatonin biosynthesis in Merlotcultivar, with a twofold rise of melatonin level detected inberry skin tissues [1].

In conclusion, despite the preliminary and incompletereports regarding melatonin in grape/wine, the presence of

this indoleamine in these products adds a new element tothe hypothesis of health benefits associated to a moderatewine consumption and, more in general, to a Mediterra-

nean dietary style, given the recent discovery of melatoninin virgin olive oil [9]. Last, but not the least, the possibilityof enhancing the pharmaconutritional potential of grape/wine with phytosanitary treatments should be further taken

into account [10].

Marcello IritiE-mail: marcello.iriti@unimi.it

References

1. Iriti M, Rossoni M, Faoro F. Melatonin content in grape:

myth or panacea? J Sci Food Agric 2006; 86:1432–1438.

2. Hernandez-Ruiz J, Cano A, Arnao MB. Melatonin acts as

a growth-stimulating compound in some monocot species.

J Pineal Res 2005; 39:137–142.

3. Kolar J, Machackova I. Melatonin in higher plants:

occurrence and possible functions. J Pineal Res 2005; 39:333–

341.

4. Arnao MB, Hernandez-Ruiz J. Melatonin promotes

adventitious – and lateral root regeneration in etiolated

hypocotyls of Lupinus albus L. J Pineal Res 2007; 42:147–

152.

5. Iriti M, Faoro F. Grape phytochemicals: a bouquet of old

and new nutraceuticals for human health. Med Hypotheses

2006; 67:833–838.

6. Marcolini L, Saracino MA, Bugamelli F et al. HPLC-F

analysis of melatonin and resveratrol isomers in wine using a

SPE procedure. J Sep Sci 2008; 31:1007–1014.

7. Guerrero JM, Martınez-Cruz F, Elorza FL. Significant

amount of melatonin in red wine: its consumption increases

blood melatonin levels in humans. Food Chem 2008; doi:

10.1016/j.foodchem.2008.02.007.

8. Burkhardt S, Tan DX, Manchester LC et al. Detection

and quantification of the antioxidant melatonin in Montmo-

rency and Balaton tart cherries (Prunus cerasus). J Agric Food

Chem 2001; 49:4898–4902.

9. De la Puerta C, Carrascosa-Salmoral MP, Garcıa-Luna

PP et al. Melatonin is a phytochemical in olive oil. Food Chem

2007; 104:609–612.

10. Fumagalli F, Rossoni M, Iriti M et al. From the field to

health: a simple, effective way to increase the nutraceutical

content of grapevine as shown by NO-dependent vascular

relaxation. J Agric Food Chem 2006; 54:5344–5349.

J. Pineal Res. 2009; 46:353Doi:10.1111/j.1600-079X.2008.00616.x

� 2008 The AuthorJournal compilation � 2008 Blackwell Munksgaard

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