Monoamine Oxidase Inhibitors Extracted from Tobacco Smoke as Neuroprotective Factors for Potential Treatment of Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disease characterized by the loss of mainly the nigrostriatal dopaminergic neurons, which leads to motor dysfunction. Although, most of the drugs are currently used for symptomatic treatment, there are at least three FDA-approved drugs for the treatment of PD that have been suggested preclinically to have neuroprotective effects. Among these drugs are monoamine oxidase (MAO) type B inhibitors such as selegiline and rasagiline, and non-ergot derivative dopamine agonist, pramipexole. In this review article, we focused on the potential uses of non-selective reversible MAO inhibitor, 2,3,6-trimethyl-1,4-naphthoquinone, from flue-cured tobacco leaves extract and two beta-carboline alkaloids (harman and norharman) as potent, reversible and non-selective MAO inhibitors for the treatment of PD. In addition, we discussed the potential uses of farnesol as a potent inhibitor of MAO-B and farnesylacetone as a less potent selective MAO-B inhibitor. Furthermore, adducts of 1,2,3,4-tetrahydroisoquinoline have shown to have competitive inhibitory effects for both MAO-A and MAO-B. These inhibitors have potential neuroprotective effects, which might be mediated at least through nerve growth factor, neurotrophin 3, brain derived neurotrophic factor, and glial-cell-line-derived neurotrophic factor. We suggest here the neuroprotective implication of extracted MAO inhibitors from smoke tobacco; however, it is important to note that there are several existing compounds in tobacco smoke that have toxic effects in the brain, these include and not limited to the induction of neuropathological features observed in individuals suffering from Alzheimer's disease and dementia.