Melatonin
Others suppose that such short exposures do no harm.
Although the primary site of melatonin's action is via the melatonin receptors, melatonin is a powerful
antioxidant that can easily cross
cell membranes and the
blood-brain barrier.
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, 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.
[ (MS Word Format)]As a natural substance with a virtual absence of problematic side effects, with health benefits to users without illnesses, melatonin has been classified as a dietary supplement and made freely available in the USA, but in the EU over the counter sale without prescription is not yet officially permitted.
Many animals use the variation in duration and quantity of melatonin production in each day as a seasonal clock.
and hamsters.
