This is an interesting paper. Usually Melatonin is not described as a potent brain protector. However, the authors of this publication see that Melatonin preserves the integrity of the blood-brain-barrier (BBB), a very selective and protective barrier around the brain. Damage to the BBB results usually in brain pathology and damage.

The title of the paper is:

Melatonin ameliorates hypoglycemic stress-induced brain endothelial tight junction injury by inhibiting protein nitration of TP53-induced glycolysis and apoptosis regulator.

It is a free download, enjoy. Link to article