Environmental exposure to the
oxidant-producing
herbicide,
paraquat (PQ) (1, 1’-dimethyl-4, 4’-bipyridinium dichloride) has long been implicated as a
risk factor in Parkinson’s
disease (PD). PQ-induced
oxidative stress has been exploited as a model to screen putative neuroprotective compounds employing
Drosophila. In the present study, we investigated the prophylactic
efficacy of
Bacopa monnieri (BM) against PQ-induced
oxidative stress,
mitochondrial dysfunctions and lethality. Exposure of
adult male flies (
Oregon K) to PQ alone (40 mM in 5%
sucrose) resulted in 50%
mortality at 48 h. Prophylaxis (7 days) with BM extract (0.1%) offered significant
protection (40%) against PQ-induced
mortality. Further, oxidative impairments and
mitochondrial dysfunctions were monitored among
Drosophila exposed to PQ (20, 40 mM) for 24 h. Significant induction of
oxidative stress was observed in terms of enhanced
malondialdehyde and
hydroperoxide levels, and elevated activities of
antioxidant enzymes (
catalase and SOD).
Mitochondrial dysfunctions included of significant reduction in the activities of
succinate dehydrogenase (23%), complex I-III (26%), and complex II-III (30%)
enzymes. Interestingly, prophylaxis with BM extract prevented the
oxidative stress induction by PQ and restored the activity of ETC complexes, suggesting clearly its specific effect on the
mitochondria. While the precise mechanism of action of BM
needs further investigations, it may be related to its
ability to enhance
antioxidant defences and thus mitigate PQ-induced
oxidative stress in
Drosophila.