Melatonin in edible plants identified by radioimmunoassay and by high performance liquid chromatography‐mass spectrometry

TLDR

Melatonin, a hormone produced by the pineal gland, is widely distributed across the animal kingdom and functions in circadian regulation, immune modulation, lifespan extension, cancer inhibition, and as a potent hydroxyl‑radical scavenger. The presence of melatonin in plants was confirmed by gas chromatography/mass spectrometry. We detected melatonin in nine plant species, with concentrations ranging from 0 to 862 pg mg⁻¹ protein, indicating that dietary intake of high‑melatonin plants could raise circulating melatonin levels and protect macromolecules from oxidative damage.

Abstract

Abstract: Melatonin, the chief hormone of the pineal gland in vertebrates, is widely distributed in the animal kingdom. Among many functions, melatonin synchronizes circadian and circannual rhythms, stimulates immune function, may increase life span, inhibits growth of cancer cells in vitro and cancer progression and promotion in vivo, and was recently shown to be a potent hydroxyl radical scavenger and antioxidant. Hydroxyl radicals are highly toxic by‐products of oxygen metabolism that damage cellular DNA and other macromolecules. Herein we report that melatonin, in varying concentrations, is also found in a variety of plants. Melatonin concentrations, measured in nine different plants by radioimmunoassay, ranged from 0 to 862 pg melatonin/mg protein. The presence of melatonin was verified by gas chromatography/mass spectrometry. Our findings suggest that the consumption of plant materials that contain high levels of melatonin could alter blood melatonin levels of the indole as well as provide protection of macromolecules against oxidative damage.