Studies also showed that extracts of ASH promote dendrite formation in human neuroblastoma cells in vitro in a dose-dependent manner. In our earlier studies, ASH extract showed growth stimulatory effects at relatively lower concentrations on SK-NMC, a Bortezomib Proteasome inhibitor neuronal cell line. Accordingly, this extract was utilized for identification of the components present as well as for other studies. HPLC and mass spectra analysis showed the presence of withanolide A as the main withanolide in the extract. Withanolides, more particularly WA are known to be responsible for the multiple medicinal properties of ASH. Many studies have utilized in vitro models to evaluate the toxicity and neurodegeneration in cells treated with Ab, still, there is lack of information regarding the mechanisms involved during the neurodegenerative processes. In the present study, the Ab treated cells, when stained with trypan blue showed several positive cells indicating cell death and cytotoxic effects compared to plain controls. However, when ASH was added to Ab treated cultures, the cytotoxic effects of Ab were neutralized and the cells were comparable to plain and ASH treated controls, suggesting the chemopreventive or protective effects of ASH against Ab induced toxicity. Toxicity mediated by excitatory amino acids is a well-documented mechanism of neurodegeneration that has also been postulated to function in Abinduced toxicity. It is possible that similar mechanisms may be responsible for the cell degeneration observed in the present study during the exposure of Ab. Accumulating evidence from different clinical studies, transgenic models as well as in vitro studies suggests that intra-neuronal accumulation of Ab as an early event that plays an important role in the pathogenesis of AD. Further, extracellular addition of Ab to neuronal cells in culture is known to induce the uptake of Ab and its localization to the nucleus. In our study, cultures treated with Ab alone showed much more marked internalization of the toxic peptide compared to cultures treated with Ab plus ASH. The plain and ASH controls showed background stain. It is likely that enhanced accumulation of Ab in neuronal cells might potentiate the peptide’s toxic effects and were counteracted by ASH as observed earlier, confirming the neuro-protective effects of ASH. In cell culture models, 3–2, 5-diphenyltetrazolium bromide, is widely used to elucidate the cellular toxicity of the Ab peptide. It is generally believed that inhibition of MTT reduction by Ab is an early indication of the Ab-induced impairment of the cellular reducing activity. Further, it has recently been reported that Ab inhibits cellular MTT reduction by enhancing MTT formazan exocytosis rather than by inhibiting MTT reduction directly. In this study, on microscopic examination, SK-N-MC cells treated with Ab and incubated with MTT showed marked appearance of needlelike exocytosed formazan crystals on the cell surface compared with the intracellular even formazan granules seen in the untreated control cells. Also both the Ab plus ASH as well as plain ASH treated cells showed intracellular even formazan granules indicating the protective and reversal effect of ASH on MTT exocytosis.