[Retracted] Natural Products for Neurodegeneration: Regulating Neurotrophic Signals

Abstract

Neurodegenerative disorders (NDs) are heterogeneous groups of ailments typically characterized by progressive damage of the nervous system. Several drugs are used to treat NDs but they have only symptomatic benefits with various side effects. Numerous researches have been performed to prove the advantages of phytochemicals for the treatment of NDs. Furthermore, phytochemicals such as polyphenols might play a pivotal role in rescue from neurodegeneration due to their various effects as anti-inflammatory, antioxidative, and antiamyloidogenic agents by controlling apoptotic factors, neurotrophic factors (NTFs), free radical scavenging system, and mitochondrial stress. On the other hand, neurotrophins (NTs) including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), NT4/5, and NT3 might have a crucial neuroprotective role, and their diminution triggers the development of the NDs. Polyphenols can interfere directly with intracellular signaling molecules to alter brain activity. Several natural products also improve the biosynthesis of endogenous genes encoding antiapoptotic Bcl-2 as well as NTFs such as glial cell and brain-derived NTFs. Various epidemiological studies have demonstrated that the initiation of these genes could play an essential role in the neuroprotective function of dietary compounds. Hence, targeting NTs might represent a promising approach for the management of NDs. In this review, we focus on the natural product-mediated neurotrophic signal-modulating cascades, which are involved in the neuroprotective effects.

Cytotoxic and Antioxidant Activities of Imine Analogs of Trans-Resveratrol towards Murine Neuronal N2a Cells

“…As aza-stilbenes have antioxidant activities, it will be further of interest to evaluate their differentiating activities on N2a cells to determine their neurotrophic effect (antioxidant activity + differentiating activity on nerve cells) [ 35 , 38 ]. This can have important applications in the context of regenerative medicine.…”

The Role of the NRF2 Pathway in Maintaining and Improving Cognitive Function

“…Another good correlate of cognitive function in vitro is synaptic density [ 52 ]. Different natural substances have been shown to induce overgrowth and neuroplasticity in vitro [ 53 ] and some of these are also known to activate the NRF2 pathway [ 54 ]. Carnosic acid, found in rosemary, which has been shown to have memory enhancing effects, has also been shown to induce neurite extension and neural differentiation through NRF2 activation in PC12h cells and the knockdown of NRF2 reduced this effect [ 55 , 56 ].…”

Tea Polyphenols as Prospective Natural Attenuators of Brain Aging

“…EC and EGC alone cannot enhance the neurite growth induced by NGF but can be used in combination with EGCG to promote the axonal growth activity of PC12 cells [ 92 ]. The combination of GTP and NGF not only increases the number of neurites, but also increases the length and branching degree of neurites [ 82 , 93 ]. This shows that there is a synergistic effect among the mixed extracts of TP—the mixture may provide a stronger effect than the individual components [ 92 , 94 ].…”