Below are the sections of each abstract that I thought were interesting and helpful.
ABSTRACT #1
Melatonin is selectively taken up by mitochondrial membranes, a function not shared by other anti-oxidants, and thus has emerged as a major potential therapeutic tool for treating neurodegenerative disorders. Multiple in vitro and in vivo experiments have shown the protective role of melatonin for preventing oxidative stress-induced mitochondrial dysfunction seen in experimental models of PD, AD, and HD. https://pubmed.ncbi.nlm.nih.gov/26087000/
For neuro-protection, not just sleep inducement, a lot melatonin is required: 50-100mg.
ABSTRACT #2
Both in vitro and in vivo, melatonin was effective to prevent oxidative stress/nitrosative stress-induced mitochondrial dysfunction seen in experimental models of AD, PD and HD. These effects are seen at doses 2-3 orders of magnitude higher than those required to affect sleep and circadian rhythms, both conspicuous targets of melatonin action. Melatonin is selectively taken up by mitochondria, a function not shared by other antioxidants. A limited number of clinical studies indicate that melatonin can improve sleep and circadian rhythm disruption in PD and AD patients. More recently, attention has been focused on the development of potent melatonin analogs with prolonged effects which were employed in clinical trials in sleep-disturbed or depressed patients in doses considerably higher than those employed for melatonin. In view that the relative potencies of the analogs are higher than that of the natural compound, clinical trials employing melatonin in the range of 50-100mg/day are needed to assess its therapeutic validity in neurodegenerative disorders. https://pubmed.ncbi.nlm.nih.gov/22391273/
ABSTRACT #3
Melatonin is a tryptophan-derived ancestral molecule evolved in bacteria.
Throughout the aging process melatonin levels tend to reduce and as a manifestation of this, many symptoms in organisms' homeostasis, such as deterioration in adjustment of cellular clocks, are commonly seen. In addition, due to deterioration in mitochondrial integrity and functions, immunity decreases, and lower levels of melatonin renders older individuals to be more susceptible to impaired redox modulation and age-related diseases. https://pubmed.ncbi.nlm.nih.gov/35895186/