Propensity of Selaginella delicatula aqueous extract to offset rotenone-induced oxidative dysfunctions and neurotoxicity in Drosophila melanogaster: Implications for Parkinson's disease.

The primary objective of this investigation was to examine the neuroprotective efficacy of an aqueous extract of Selaginella delicatula (a pteridophyte) employing a rotenone (ROT) Drosophila model in vivo. Aqueous extract of S. delicatula (SDAE) exhibited multiple antioxidant activity in selected chemical systems. Initially, we examined the ability of SDAE-enriched diet to modulate the levels of endogenous oxidative markers and antioxidant defenses in Drosophila melanogaster. Further, employing a co-exposure paradigm, we investigated the propensity of SDAE to protect flies against ROT-induced lethality, locomotor dysfunction, oxidative stress, mitochondrial dysfunctions and neurotoxicity. Adult flies were fed SDAE-enriched diet (0.05, 0.1 and 0.2%) with or without ROT (500 μM) for seven consecutive days. SDAE offered concentration-dependent protection against ROT-induced lethality (30-95% protection), while the survivor flies performed better in the negative geotaxis assay suggesting attenuation of ROT-induced locomotor deficits. Biochemical analysis revealed that SDAE completely restored ROT-induced elevation in the levels of ROS, protein carbonyls and hydroperoxides in both head and body regions of flies. Elevations in the activities of antioxidant enzymes (superoxide dismutase, glutathione reductase) and glutathione-S-transferase caused by ROT were also restored to normal levels by SDAE. Further, SDAE improved the activity levels of membrane bound enzymes viz., NADH-cytochrome c reductase and succinate dehydrogenase suggesting its propensity to protect mitochondrial integrity. Interestingly, SDAE normalized the activity levels of acetylcholinesterase and ROT-induced dopamine depletion. Collectively, these findings suggest the neuromodulatory potential of SDAE and our further studies are directed toward characterization of the nature of biomolecule/s and their mechanism of action employing relevant cell models.