In Vitro Antioxidant Activity and In Vivo Neuroprotective Effect of Parastrephia quadrangularis in a Drosophila...

Oxidative stress (OxS) is a central factor in neurodegenerative diseases (NDs), including Parkinson's disease (PD). Phenolic compounds, including flavonoids and coumarins, counteract reactive species and modulate key intracellular survival pathways, highlighting their therapeutic potential. Parastrephia quadrangularis (Pq), a plant from the Atacama Desert traditionally used by Andean communities, contains phenolic compounds with antioxidant, antifungal, and anti-inflammatory activities. However, its neuroprotective potential remains unexplored. Here, a hydroalcoholic extract (HAE) of Pq and four subfractions (MeOH, EtOAc, DCM, and n-hex) were obtained and assessed for in vitro antioxidant activity, with HAE selected for its consistent activity. In SH-SY5Y cells, HAE-Pq lowered basal reactive oxygen species and attenuated hydrogen peroxide-induced OxS. The UHPLC-MS analysis of HAE-Pq unveiled a high abundance of flavonoids, followed by coumarins and phenolic acids, and identified 16 additional metabolites, including jaceidin as the most abundant. In vivo assays using a Drosophila genetic PD model induced by overexpression of human α-synuclein, showed that HAE-Pq was non-toxic and non-aversive and that it delayed the onset of motor defects by one week in female flies. This study provides the first evidence of the neuroprotective potential of Pq, supporting its value as a source of bioactive metabolites relevant to NDs and reinforcing its ethnopharmacological validation.