Weakness melatonin

Despite some literature data, melatonin is not a free radical scavenger because it does not contain the substituents with a weak C—H or O—H bonds. Suggestions that melatonin may reduce free radicals through a one-electron transfer mechanism are very interesting but they still were not confirmed by any kinetic measurements. 

Ramelteon is a hypnotic with melatonin receptor agonist activity targeting melatonin MTj and MT2 receptors. It has not been proven to induce dependence. As with zolpidem and zaleplon, no known anxiolytic properties have been elicited. No appreciable activity on serotonin, dopamine, GABA, or acetylcholine is present with the parent compound, but in vitro studies report that its primary metabolite M-II has weak 5-HT2g receptor agonist activity. 

In vitro, melatonin did not scavenge superoxide radical and weakly protected DNA against damage... 

Circadin is a prolonged-release tablet containing melatonin 2 mg. It has received European Medicine Agency approval for treatment of primary insomnia. Adverse reactions are uncommon, but include headache, pharyngitis, back pain, and weakness. There do not appear to be withdrawal effects. 

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