Preclinical and Potential Applications of Common Western Herbal Supplements as Complementary Treatment in Parkinson's Disease.

Parkinson's disease (PD) is a neurological disorder with a complex pathological etiology, which is not fully understood. Progression of PD may be the result of a buildup of iron in the substantia nigra, microglia-mediated neuroinflammation, dysfunctional mitochondria, or abnormal protein handling. Dopamine is the main neurotransmitter affected, but as the disease progresses, a decrease in all the brain's biogenic amines occurs. Current medication used in the treatment of PD aims to prevent the breakdown of dopamine or increase dopaminergic neurotransmission in the central nervous system. The complementary use of green tea (Camellia sinensis), red wine (Vitis vinifera), arctic root (Rhodiola rosea), and dwarf periwinkle (Vinca minor) may have a greater therapeutic effect than current pharmaceutical drugs, such as monoamine oxidase inhibitors or dopamine agonists alone. The bioactive components of these plants have been shown to have neuroprotective, antioxidant, anti-proteinopathies, neural-vasodilation, anti-inflammatory, and iron chelating potential. They may treat the disease at the cellular level by decreasing microglia activation, attenuating damage from radical oxygen species, supporting correct protein folding, chelating iron, increasing the substantia nigra blood flow, and promoting dopaminergic cell growth. Although these alternative medicines appear to have potential, further human clinical trials need to be conducted to determine whether they could have a greater therapeutic effect than conventional medicines alone.