Novel Insight to Neuroprotective Potential of Curcumin: A Mechanistic Review of Possible Involvement of Mitochondrial Biogenesis and PI3/Akt/ GSK3 or PI3/Akt/CREB/BDNF Signaling Pathways

Neurodegeneration is a gradual mechanism of neuronal loss arising from numerous cellular and molecular events such as mitochondrial dysfunction, oxidative stress, inflammation, and apoptosis, and the consequence of these processes is neuroplasticity impairment, cognitive diseases, mood-related diseases, and normal cellular activity. Over the last year, major advances have been made in the field of the introduction of herbal compounds with neuroprotective efficacy, one of which is curcumin. Curcumin (diferuloylmethane) is the most abundant turmeric component extracted from the Curcuma longa plant rhizomes. Accumulating evidence indicates that curcumin may induce mitochondrial biogenesis and can function as an antioxidant, anti-inflammatory, and anti-apoptotic agent, which may be used effectively to treat chronic neurodegenerative diseases and any situation in which the neurodegeneration process takes place. Curcumin has been shown to play a critical role in activating two essential signaling pathways phosphatidylinositol-3(PI3)/ protein kinase B(Akt)/ glycogen synthase kinase-3 (GSK3) and PI3/Akt/cAMP response element-binding protein (CREB)/brain-derived neurotrophic factor (BDNF) and preventing the incidence of neurodegeneration via these two pathways. Curcumin's protective functions against neural cell degeneration due to mitochondrial dysfunction and consequent events such as oxidative stress, inflammation, and apoptosis in neural cells have been documented and clinical data have increased to suggest that curcumin may be a standard candidate as a neuroprotective agent. Therefore, in this review, we summarized the clinical and experimental studies and interpreted the key contributory mechanisms of neuroprotective properties of curcumin in neurodegenerative diseases and disorders. We also tried to understand the function of PI3/Akt/GSK3 and PI3/Akt/CREB/BDNF signaling pathways in the neuroprotective properties of curcumin and tried to evaluate their association with antioxidant, anti-inflammatory, anti-apoptosis and biogenesis effects of mitochondria.