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Melatonin Suppresses Reactive Oxygen Species in UV-Irradiated Leukocytes More than Vitamin C and Trolox

2002; Karger Publishers; Volume: 15; Issue: 5 Linguagem: Inglês

10.1159/000064543

1660-5535

Tobias W. Fischer, Georg Scholz, Brunhilde Knöll, Uta‐Christina Hipler, Peter Elsner,

Light effects on plants

To prove the relative potency of melatonin as a radical scavenger in UV-irradiated leukocytes, it was compared to other antioxidative substances such as trolox and vitamin C. Human leukocytes were isolated from EDTA whole blood and incubated with melatonin, trolox and vitamin C. The experiments were performed in a wide concentration range from 0.1 n<i>M</i> to 1 m<i>M</i> and in a small concentration range from 0.5 to 2 m<i>M</i> (mel), 5 m<i>M</i> (trolox) and 10 m<i>M</i> (vit. C). Irradiation was performed with UV-light (280-360 nm) at a dose of 750 mJ/cm². Radical formation was measured by the chemiluminescence technique. The maximum effect of radical suppression was seen at a concentration of 10 n<i>M</i> (p = 0.003) and 1 m<i>M</i> melatonin (p < 0.001) and vitamin C (p = 0.002; p < 0.001), respectively. ROS suppression by trolox was only significant at 1 m<i>M</i> (p < 0.001). In the small concentration range, a linear dose-response relationship was found and melatonin showed the strongest radical suppression (IC₅₀ = 0.21 m<i>M</i>) followed by vitamin C (IC₅₀ = 0.26 m<i>M</i>) and trolox (IC₅₀ = 1.03 m<i>M</i>).