Not much is ever mentioned about melatonins antioxidant ability, it helps very little for my sleep ie doesnt put me to sleep but helps more body clock issues i guess, but i mainly use it for its antioxidant ability especially in the brain.
Antioxidant
Besides its function as synchronizer of the biological clock, melatonin also exerts a powerful antioxidant activity. In many less complex life forms, this is its only known function.
[34] Melatonin is an
antioxidant that can easily cross
cell membranes and the blood–brain barrier.
[6][35] Melatonin is a direct scavenger of OH, O
2−, and NO.
[36] Unlike other antioxidants, melatonin does not undergo
redox cycling, the ability of a
molecule to undergo
reduction and
oxidation repeatedly. Redox cycling may allow other antioxidants (such as vitamin C) to act as pro-oxidants, counterintuitively promoting free radical formation. Melatonin, on the other hand, once oxidized, cannot be reduced to its former state because it forms several stable end-products upon reacting with free radicals. Therefore, it has been referred to as a terminal (or suicidal) antioxidant.
[37]
Recent research indicates that the first metabolite of melatonin in the melatonin antioxidant pathway may be N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (or AFMK) rather than the common, excreted 6-hydroxymelatonin sulfate. AFMK alone is detectable in unicellular organisms and
metazoans. A single AFMK molecule can neutralize up to 10
ROS/RNS (reactive oxygen species/reactive nitrogen species) since many of the products of the reaction/derivatives (including melatonin) are themselves antioxidants. This capacity to absorb free radicals extends at least to the quaternary metabolites of melatonin, a process referred to as "the free radical scavenging cascade." This is not true of other, conventional antioxidants.
[34]
In animal models, melatonin has been demonstrated to prevent the damage to DNA by some
carcinogens, stopping the mechanism by which they cause cancer.
[38]
It also has been found to be effective in protecting against brain injury caused by
ROS release in experimental hypoxic brain damage in newborn rats.
[39] Melatonin's antioxidant activity may reduce damage caused by some types of
Parkinson's disease, play a role in preventing cardiac
arrhythmia and possibly increase
longevity; it has been shown to increase the
average life span of
mice by 20% in some studies.
[40][41][42]
[edit] Immune system
While it is known that melatonin interacts with the
immune system,
[43][44] the details of those interactions are unclear. There have been few trials designed to judge the effectiveness of melatonin in disease treatment. Most existing data are based on small, incomplete clinical trials. Any positive immunological effect is thought to result from melatonin acting on high affinity receptors (MT1 and MT2) expressed in immunocompetent cells. In preclinical studies, melatonin may enhance
cytokine production,
[45] and by doing this counteract
acquired immunodeficiences. Some studies also suggest that melatonin might be useful fighting infectious disease
[19] including viral, such as
HIV, and bacterial infections, and potentially in the treatment of
cancer.
[46]
Endogenous melatonin in human
lymphocytes has been related to
interleukin-2 (IL-2) production and to the expression of IL-2 receptor.
[47] This suggests that melatonin is involved in the clonal expansion of antigen-stimulated human
T lymphocytes. In
rheumatoid arthritis patients, melatonin production has been found increased when compared to age-matched healthy controls.
[48]
Although it has not yet been clearly demonstrated whether melatonin increases non-specific
immunity with resulting
contraindication in
autoimmune diseases, an increase in the production of
IL-2 and
IL-1 was noted in cultured
splenocytes.
[49]