Selegiline, also known as l-deprenyl, is an irreversible and (relatively) selective MAO-B inhibitor. Meta-analysis of published clinical trials confirms it offers a cheap, safe and effective symptomatic treatment of early Parkinson's disease. Selegiline may also be neuroprotective and act as an antidepressant.

Selegiline has immune-system-boosting and anti-neurodegenerative effects. Its use increases the level of tyrosine hydroxylase, growth hormone, cerebral nitric oxide and the production of key interleukins. Selegiline offers protection against DNA damage and oxidative stress by hydroxyl and peroxyl radical trapping; and against excitotoxic damage from glutamate. In addition, selegiline stimulates the release of superoxide dismutase (SOD). SOD is a key enzyme which helps to quench the production of damaging free-radicals. Potentially, selegiline may prevent or reverse iron-induced memory impairment. The deposition of excess iron in the brain is implicated several neurodegenerative diseases.

Selegiline protects the mitochondria via its effects on mitochondrial membrane permeability: it directly interacts with the pore-forming structures. Mitochondria are the energy powerhouses of the eukaryotic cell where oxygen respiration occurs. If the mitochondrial theory of aging is correct, then the root cause of aging is damage to mitochondrial DNA by free radical leakage from adjacent respiratory proteins. Alas selegiline itself is not an elixir of eternal youth. But its current "off-label" use by life-extensionists prefigures the longevity-enhancing mitochondrial medicine of decades to come.

Taken consistently in low doses, selegiline tends to extend the life-expectancy of rats by some 20%; enhances drive, libido and endurance; and independently improves cognitive performance in Alzheimer's patients and in some healthy normals. Its protective role against age-related memory decline derives at least in part from its protection of hippocampal neurons in the aging brain. Aging drug-free rats have poorer spatial memories and fewer hippocampal neurons than their counterparts on selegiline. Selegiline is already used successfully to treat canine cognitive dysfunction syndrome (CDS) in dogs.Selegiline retards the metabolism not just of dopamine but also of phenylethylamine, a trace amine also found in chocolate and released when we're in love. Selegiline protects the brain's dopamine cells from oxidative stress. The brain has only about 30-40 thousand dopaminergic neurons in all. We tend to lose perhaps 13% a decade in adult life. An eventual 70%-80% loss leads to the dopamine-deficiency disorder Parkinson's disease, frequently foreshadowed by depression.

Deprenyl?s low level of toxicity, few side-effects, and unique spectrum of pharmacological activities make it ideal for prophylaxis against nigrostriatal aging and the secondary aging symptoms accompanying the decline of the dopaminergic nervous system. Deprenyl is a drug of choice for Parkinson?s disease and is currently being established as a treatment for Alzheimer?s disease. Eventually, deprenyl may become recognized as a general treatment for aging in the above-45-year-old population.

Before taking any prescription medicine, it is important that you consult your doctor!