Chapter 9 - Possible Anti-Parkinson’s Disease Therapeutics From Nature: A Review

Abstract

Abstract Parkinson's disease (PD) is an idiopathic degenerative disorder of the central nervous system commonly affecting the elderly. In PD, dopaminergic neurons in the substantia nigra of the ventral midbrain selectively degenerate causing a number of movement disorders such as shaking, rigidity, slowness of movement, bradykinesia, and others, as early symptoms and cognitive and behavioural problems associated with dementia occurring at the later stages. Currently, the dopamine (DA) precursor, levodopa (L-DOPA), and DA agonists are used to manage the early motor symptoms associated with PD, but during the later stages, these drugs become ineffective and the treatment in the long run might cause motor complications, dyskinesia, and decreased drug response and drug-induced toxicity. Monoamine oxidase inhibitors and catechol-O-methyltransferase inhibitors have also been tried but, overall, the anti-PD treatments seem to be very limited. For this reason, as an alternative independent therapeutic approach or an aid to the existing therapy, a wide range of natural substances with neuroprotective properties have been tested for their potent anti-PD activity. Amelioration of neurotoxic effects of certain anti-PD drugs by herbal treatments has also been reported. Traditional and complementary therapies also include herbal preparations subjected to be evaluated for active constituents with anti-PD activities. Plants such as Olea europaea, Hypericum perforatum, Ginkgo biloba, Mucuna pruriens, Banisteria caapi, Polygonum cuspidatum, Withania somnifera, Gynostemma pentaphyllum, Glycine max, Trifolium pretense, and Scutellaria baicalensis have been reported to possess anti-PD activities. Recently, natural compounds such as oleuropein, hyperforin, silymarin, melatonin, resveratrol, baicalin, cistanche total and phenylethanoid glycosides, ginsenoside, salvianolic acid B, salvianic acid A, astaxanthin, triptolide, genistein, biochanin A, luteolin, and others, have been evaluated in vivo for anti-PD and neuroprotective activities. Natural compounds exert their anti-PD effects by inhibiting microglial activation to protect inflammation-mediated degeneration of dopaminergic neurons and by inhibiting proinflammatory factors or superoxide generation. The present review also focuses on certain traditional herbal anti-PD treatments with traditional Chinese medicine, for example, Zhen-Wu-Tang, Bushen Huoxue Granule, Yokukansan, and others. In a nutshell, the review deals with the literature covering use of botanical-derived natural products, either as crude extracts or isolated compounds in monoherbal or polyherbal formulations, having anti-PD activity with notes on source plant, active component, experimental methodology, and ethnopharmacological relevance of anti-PD efficacy of the natural compounds.