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 coexposure
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 mM) 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.