Cytoprotective and antioxidant effects of an edible herb, Enhydra fluctuans lour. (Asteraceae), against experimentally induced lead acetate intoxication

Background: Enhydra fluctuans Lour. (Asteraceae), an edible aquatic herb, is traditionally employed against toxic effects of heavy metals in India. The present study was planned to discover the protective effect of edible extract of E. fluctuans (AEEF) against Pb toxicity. Methods: The cytoprotective role of AEEF was determined on murine hepatocytes employing MTT assay and Hoechst staining. The effects on lipid peroxidation, protein carbonylation, endogenous redox systems and the transcription levels of apoptotic proteins were studied after incubating the hepatocytes with AEEF (400 μg/ml) + Pb-acetate (6.8 μM). The defensive role of AEEF (100 mg/kg) against Pb-acetate (5 mg/kg) intoxication was measured in mice by in vivo assays. Biochemical, haematological and histological parameters, intracellular Pb burden and redox status were measured. Results: AEEF exhibited a concentration dependent cytoprotective effect against Pb-induced cytotoxicity in vitro. Pb-acetate incubation significantly (p < 0.01) altered the extents of ROS production ↑, protein carbonylation ↑, lipid peroxidation ↑, endogenous antioxidant enzymes ↓ and GSH ↓ in vitro. Besides, Pb-acetate significantly (p < 0.01) induced apoptosis in the hepatocytes apparent from the altered expressions of apoptotic proteins viz. Apaf-1 ↑, Bad ↑, Bcl-2 ↓, Cyt C ↑, cleaved caspases↑, Bid ↑ and Fas ↑. However, AEEF (400 μg/ml) could significantly (p < 0.05-0.01) attenuate the Pb-acetate mediated toxic manifestation in vitro. In in vivo assay, Pbacetate (5 mg/kg) treated mice exhibited significantly (p < 0.01) high intracellular Pb content. A high Pb-burden within the tissues caused significant (p < 0.05-0.01) patho-physiological alterations viz. ROS production ↑, protein carbonylation↑, lipid peroxidation ↑, DNA fragmentation ↑, ATPformation ↑, mitochondrial co-enzymes Q ↓, endogenous antioxidant enzymes ↓ and GSH ↓ within the selected tissues. The haematological and serum biochemical parameters were significantly (p < 0.05-0.01) different in the Pb-acetate treated mice. Finally, histological assessment imposed significant toxic occurrence within the organs of Pb-intoxicated animals. However, concurrent administration of AEEF (100mg/kg) could significantly (p < 0.05-0.01) reinstate the Pb-acetate mediated toxicity. Conclusion: Presence of metal chelators and phyto-antioxidants within AEEF would offer overall protection through promoting Pb clearance coupled with restoring redox balance.