Identification through high-throughput screening of 4′-methoxyflavone and 3′,4′-dimethoxyflavone as novel neuroprotective inhibitors of parthanatos

Background and Purpose The current lack of disease-modifying therapeutics to manage neurological and neurodegenerative conditions justifies the development of more efficacious agents. One distinct pathway leading to neuronal death in these conditions and which represents a very promising and attractive therapeutic target is parthanatos, involving overactivation of PARP-1. We therefore sought to identify small molecules that could be neuroprotective by targeting the pathway. Experimental Approach Using HeLa cells, we developed and optimized an assay for high-throughput screening of about 5120 small molecules. Structure-activity relationship (SAR) study was carried out in HeLa and SH-SY5Y cells for molecules related to the initial active compound. The neuroprotective ability of each active compound was tested in cortical neuronal cultures. Key Results 4'-Methoxyflavone (4MF) showed activity by preventing the decrease in cell viability of HeLa and SH-SY5Y cells caused by the DNA-alkylating agent, N-methyl-N-nitro-N-nitrosoguanidine (MNNG), which induces parthanatos. A similar compound from the SAR study, 3',4'-dimethoxyflavone (DMF), also showed significant activity. Both compounds reduced the synthesis and accumulation of poly (ADP-ribose) polymer and protected cortical neurones against cell death induced by NMDA. Conclusions and Implications Our data reveal additional neuroprotective members of the flavone class of flavonoids and show that methoxylation of the parent flavone structure at position 4 confers parthanatos-inhibiting activity while additional methoxylation at position 3, reported by others to improve metabolic stability, does not destroy the activity. These molecules may therefore serve as leads for the development of novel neurotherapeutics for the management of neurological and neurodegenerative conditions.