A Critical Analysis of Quercetin as the Attractive Target for the Treatment of Parkinson's Disease

Abstract

: Parkinson's disease (PD) is a multifaceted disorder with various factors that have been suggested to play a synergistic pathophysiological role, such as oxidative stress, autophagy, pro-inflammatory events, and neurotransmitter abnormalities. While it is crucial to discover new treatments in addition to preventing PD, recent studies have focused on determining whether nutraceuticals will exert neuroprotective actions and pharmacological functions in PD. Quercetin, a flavonol- type flavonoid, is found in many fruits and vegetables and has been recognized as a complementary therapy for PD. The neuroprotective effect of quercetin is directly associated with its antioxidant activity, in addition to stimulating cellular defense against oxidative stress. Other related mechanisms are activating sirtuins (SIRT1) and inducing autophagy, in addition to induction of Nrf2-ARE and paraoxonase 2 (PON2). Quercetin, whose neuroprotective activity has been demonstrated in many studies, unfortunately, has a disadvantage because of its poor water solubility, chemical instability, and low oral bioavailability. It has been reported that the disadvantages of quercetin have been eliminated in studies with nanocarriers loaded with quercetin. The role of nanotechnology and nanodelivery systems in reducing oxidative stress during PD provides an indisputable advantage. Accordingly, the aim of the present review is to shed light on the beneficial effects and underlying mechanisms of quercetin in neuroprotection. In addition, the contribution of nanodelivery systems to the neuroprotective effect of quercetin will be discussed.