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Therapeutic Potential of a Red Dragon Fruit, Hylocereus polyrhizus, Ethanol Extract in an hSOD1G93A Mouse Model of Amyotrophic Lateral Sclerosis: Isolation and Characterization of Other Novel Red Dragon Fruit Extracts Enriched in Betacyanin Compounds

Amyotrophic lateral sclerosis (ALS) is a progressive, fatal neurodegenerative disease that leads to death of upper and lower motor neurons via increases in factors like oxidative stress, neuroinflammation and dysfunctional antioxidant enzymes, amongst others. Progressive cell death results in a reduction of voluntary muscular function and eventual respiratory failure. Supplementation with natural compounds like flavonoids and other polyphenols has exhibited therapeutic effects in addressing some of the underlying mechanisms in ALS pathology. Betacyanins, a class of polyphenol, are found in high concentration in red dragon fruit (RDF) and have shown notable anti-inflammatory and antioxidant effects in vitro, but in vivo studies are lacking. The effects of RDF ethanol extract supplementation on survival, bodyweight, and motor function were assessed in an hSOD1G93A mouse model of ALS. RDF flesh contains flavonoids and betacyanins, so a novel acid-base extraction of RDF was conducted and spectrophotometrically analyzed to aid in future procedures to investigate synergistic effects of these compounds. Additionally, a formic acid-ether extraction of RDF was completed with a crude purification via FPLC to determine concentration of betanin in fruit samples. LC-MS analysis was conducted in order to characterize the predominant compound(s) in all three extraction methods. Oral administration of RDF ethanol extract resulted in significant elongation of lifespan, preservation of bodyweight and increases in grip strength and motor function in treated hSOD1G93A ALS mice. HPLC analysis determined relative betanin and isobetanin quantities in various extracts. Formic acid-ether extraction and purification exhibited high betanin and isobetanin yield confirmed by LC-MS analysis. Abundant deglycosylation of betanin in ethanol and acid-base extracts was confirmed via LC-MS analysis. Implications include a lack of knowledge of the actual molecular mechanisms of these polyphenolic compounds in mice, as well as the apparent degradation of betanin in the ethanol and acid-base extracts. Future experiments will address these issues.