Epigallocatechin-3-Gallate, Quercetin, and Kaempferol for Treatment of Parkinson's Disease Through Prevention of Gut Dysbiosis and Attenuation of Multiple Molecular Mechanisms of Pathogenesis.

Parkinson's disease (PD) is a neurodegenerative condition in which degeneration mostly occurs in the dopamine (DA)-producing neurons within the substantia nigra in the midbrain. As a result, individuals with this condition suffer from progressively worsening motor impairment because of the resulting DA deficiency, along with an array of other symptoms that, over time, force them into a completely debilitating state. As an age-related disease, PD has only risen in prevalence over the years; thus, an emphasis has recently been placed on discovering a new treatment for this condition that is capable of attenuating its progression. The gut microbiota has become an area of intrigue among PD studies, as research into this topic has shown that imbalances in the gut microbiota (colloquially known as gut dysbiosis) seemingly promote the primary etiologic factors that have been found to be associated with PD and its pathologic progression. With this knowledge, research into PD treatment has begun to expand beyond synthetic pharmaceutical compounds, as a growing emphasis has been placed on studying plant-derived polyphenolic compounds, namely flavonoids, as a new potential therapeutic approach. Due to their capacity to promote a state of homeostasis in the gut microbiota and their long-standing history as powerful medicinal agents, flavonoids have begun to be looked at as promising therapeutic agents capable of attenuating several of the pathologic states seen amidst PD through indirect and direct means. This review article focuses on three flavonoids, specifically epigallocatechin-3-gallate, quercetin, and kaempferol, discussing the mechanisms through which these powerful flavonoids can potentially prevent gut dysbiosis, neuroinflammation, and other molecular mechanisms involved in the pathogenesis and progression of PD, while also exploring their real-world application and how issues of bioavailability and potential drug interactions can be circumvented or exploited.