In the present study, effect of doxorubicin at 2 mg/kg b.wt. (i/p), alone, once in a wk for 4 wks and in combination with vitamin E at 250 and 500 mg/kg b.wt., orally, daily for 4 wks was evaluated on histological alterations, if any, on heart, liver, kidney, and testes of rats. Doxorubicin alone treated group showed marked congestion and degenerative changes in heart, kidney, liver, and testis. Treatment with vitamin E showed marked improvement in all the degenerative changes, though more protection was observed with the dose of 500 mg/kg.

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The antioxidant properties of plants could be correlated with oxidative stress defence in different human diseases. The present study was undertaken to evaluate and compare the antioxidant potential and the phytochemical composition in the aqueous extracts of mint leaves, black tea and black tea enriched with mint extract. All the three preparations exhibited free radical-scavenging potential for nitric oxide (NO) radical, superoxide anion radical and hydroxyl radical, and the values were lesser than those of the antioxidants which acted as standards. In comparison, the mint extract exhibited higher free radical and NO scavenging effect. Hydroxyl radical and superoxide scavenging effects were more pronounced in tea with the mint extract, while the reducing power was exhibited more significantly by the black tea extract. The phytochemical compounds were identified and the total phenols and flavonoids were quantified and compared between these extracts.

Oxidative stress causes damage at the cellular level and activates a number of signaling pathways. Earlier, we have demonstrated that pollutant-related oxidative stress upregulates heat-shock protein 90 alpha (HSP90α) against stress insult in hepatocytes of Mugil cephalus living in a polluted estuary. However, the impact of pollution-induced HSP90α upregulation on stress tolerance is not clear. Here we propose that the effect of stress resistance depends on the ability of HSP90α to modulate the signaling pathways involving proteins such as apoptosis signal-regulating kinase 1, c-Jun NH 2 -terminal protein kinase 1/2, signal transducers and activators of transcription, extracellular signal-regulated kinase 1/2, protein kinase B, nuclear factor-kappa binding, Ets-like protein 1, and B cell lymphoma-2. In order to investigate this, the activation of HSP90α-associated signaling molecules was examined by Western blotting and immunohistochemistry. The relationship between the protein expression patterns was identified by Spearman's rank correlation analysis. The signaling proteins exhibited differential modulation as revealed from their expression patterns in pollutant-exposed fish hepatocytes, in comparison with the control fish hepatocytes. The results suggested that in spite of the prevalence of oxidative stress in pollutantexposed fish hepatocytes, the stress-mediated induction of HSP90α enabled the hepatocytes to become stress tolerant and to survive by modulating the actions of key proteins and kinases in the signal transduction pathways.