**11.10 Melatonin**

Melatonin is produced by the pineal gland and have bleaching action on skin pigment i.e. melanin. Melatonin is used as a protective agent against various processes and agents which damage the tissue via free radicals. Melatonin is found in all living organism. As we know that melatonin is a naturally occurring hormone and chemically is N-acetyl-5-methoxytryptamine [78] and found in animals and in algae [79].

Melatonin is highly lipophilic in nature and having an ability to cross various barriers like cell membrane as well as highly selective barriers like BBB [80]. Melatonin also known as 'suicidal anti-oxidant' because it cannot be recycled when it reduced to its former state [81].
