Comparative Study of a Potent CNS-Permeable RARβ-Modulator, Ellorarxine, in Neuronal Cells In Vitro

.Vitamin A (retinol) and its derivatives (retinoids) assume critical roles in neural development, cellular differentiation, axon elongation, programmed cell apoptosis and various fundamental cellular processes. Retinoids function by binding to specific nuclear receptors, such as retinoic acid receptors (RARs) and retinoid X receptors (RXRs), activating specific signaling pathways in the cells. Disruption of the retinoic acid signaling pathway can result in neuroinflammation, ox-idative stress, mitochondrial dysfunction and neurodegenerative processes, and has been asso-ciated with a range of neurodegenerative diseases. The present study explores the potential therapeutic application of our innovative synthetic retinoid, Ellorarxine, also known as DC645 and NVG0645, for the treatment of neurodegenerative disorders in vitro. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium assay, lactate dehy-drogenase (LDH) assay, enzyme-linked immunosorbent assay (ELISA), senescence-associated (SA) β-galactosidase (β-gal) staining and immunofluorescence staining were performed. The re-sults showed that no cytotoxicity was detected at the experimental concentrations of Ellorarxine. Ellorarxine significantly reduced cell death, increased mitochondrial viability, reduced the num-ber of senescent cells, modulated cytokine release and regulated cellular autophagy. Furthermore, Ellorarxine also increased Cyp26 and selectively RARβ expression. These results make Ellorarxine a promising drug candidate that should be further investigated in the treatment of neurodegenerative diseases. .