Allosteric Activation of SIRT1 by 2,4-Dihydroxy-azaflavanone Averts MPP + -Mediated Dysfunction in Mitochondrial Biogenesis and Bioenergetics: Implications for Parkinson's Disease.

Parkinson's disease (PD) is a complex neurodegenerative disorder that affects dopamine neurons of the substantia nigra pars compacta (SNpc), resulting in motor dysfunction. Among the pathways examined, mitochondria and α-synuclein were found to play a major role in the disease progression. Hence, several attempts are being made to restore mitochondrial bioenergetics or protein aggregation pathways as disease-modifying strategies. Our earlier studies reported the protective effect of 2,4-dihydroxy-azaflavanone (azaflavanone) in a transgenic Drosophila fly model of PD. In the present study, we found that azaflavanone acts as an allosteric activator of SIRT1 in both cell-free and cell-based systems and the effects were more pronounced as compared to resveratrol. Also, azaflavanone appears to interact selectively with SIRT1 as other SIRTs such as SIRT3 and SIRT6 did not exhibit any gross changes in cellular thermal shift assay (CETSA). Molecular docking studies depicted a higher docking score with azaflavanone than with resveratrol. Further, N27 cells treated with azaflavanone exhibited a dose-dependent increase in the mitotracker staining, mtDNA/nuclear DNA ratio, and also mitochondrial bioenergetics. The observed effects appear to be due to the activation of SIRT1, as evidenced by an increase in the expression of PGC-1α and TFAM, which are the downstream targets of SIRT1. Lastly, the Parkinsonian mimic MPP ⁺ -induced disturbance in the mitochondrial membrane potential, mitochondrial bioenergetics, and biogenesis were ameliorated by azaflavanone. Overall, our findings indicate that azaflavanone, being an antioxidant and an allosteric activator of SIRT1, is a promising compound for ameliorating the pathophysiology of PD.