Preclinical study of red dragon fruit (Hylocereus polyrhizus) betacyanins in the G93A mutant hSOD1 mouse model of amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by loss of cortical and spinal motor neurons, oxidative stress, neuroinflammation, and mitochondrial dysfunction. Betacyanins, betalain pigments found in red dragon fruit and beetroot, display powerful anti-inflammatory and free-radical scavenging properties which may help ameliorate ALS pathology and slow disease progression. The present study characterized the therapeutic effects of a betacyanin-rich red dragon fruit extract (DFE) in the G93A mutant hSOD1 transgenic mouse model of ALS. Mice were treated orally with 5% (v/v) DFE in drinking water ad libitum, from disease onset until end-stage. DFE treatment had a statistically significant effect on survival, with an approximate 13-day extension of median lifespan in the treated G93A mutant hSOD1 group. Treatment with DFE also significantly preserved muscle strength and endurance, as assessed by grip strength and rotarod behavioral testing. This was associated with a modest but statistically significant preservation of gastrocnemius muscle weight in the DFE-treated group. Histopathological analyses demonstrated improvements in NMJ size and complexity, an increase in surviving spinal cord motor neurons, and a reduction in spinal cord astrogliosis in G93A mutant hSOD1 mice treated with DFE, when compared to their untreated mutant littermates. Overall, these findings indicate that DFE, or purified betacyanin compounds, should be investigated further as potential therapeutic agents for patients with SOD1-related ALS. Additional preclinical studies in non-SOD1 models of ALS will need to be completed to determine the potential benefit of betacyanin compounds in sporadic ALS.