Melatonin and Polyphenol Contents in Some Edible Sprouts (Alfalfa, Chicory, Rape, Red Kale and Sunflower)

Abstract

The melatonin, total polyphenol contents, and DPPH radical scavenging activity were determined in alfalfa, chicory, rape, red kale and sunflower after germination for four days at 24±0.1℃. Compared with seeds, melatonin content was increased in all sprouts, at the highest level in red kale (2,502.9 pg/g, 5.6 times higher than seed) followed by rape (2,430.1 pg/g), chicory (2,037.7 pg/g), alfalfa (1,160.8 pg/g) and sunflower (768.2 pg/g) sprout, however, the addition of tryptophan (0.5 mM), the precursor of melatonin synthesis, did not show any desirable effect. Both polyphenol content and DPPH radical scavenging activity were substantially increased in chicory (8.7 ㎎/g, 66%), rape (10.7 ㎎/g, 51%) and red kale (11.0 ㎎/g, 53%) sprouts, but not in alfalfa and sunflower sprouts. Melatonin content per gram polyphenol (ng/g) was also increased in all sprouts through germination. Germination was effective in increasing melatonin in all seeds tested, while its effect on polyphenol content and DPPH radical scavenging activity was species dependent.