Environmental exposure to lead (Pb) is reported to associate with the development of Alzheimer's disease, where the formation of β-amyloid peptides (APs) of (1-40),(1-42), and (25-35) is considered as the major risk factor. In this context, we aimed at investigating the effect of epigallocatechin gallate (EGCG), a major flavonoid polyphenol available in green tea, in mitigating the individual and combined toxicity generated by Pb and β-APs in terms of oxidative stress and apoptosis in human neuronal cells. SH-SY5Y cells were exposed to Pb and β-APs of (1-40) and (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) individually and in different combinations in the presence and absence of EGCG. The results indicated that EGCG mitigated both Pb-and β-AP-induced oxidative stress in scavenging reactive oxygen species and apoptosis by improving the expression levels of Bax and bcl2 and inhibiting annexin V and caspase-3. Thus, our study shows that EGCG protects SH-SY5Y cells against the cytotoxicity induced by Pb and β-APs by decreasing oxidative stress and inhibiting apoptosis.
K E Y W O R D Sapoptosis, human brain cells, in vitro, lead, β-amyloid peptides
The formation of β amyloid plaques is one of the pathological hallmarks of Alzheimer's disease (AD). The process of accumulation of extracellular deposits of amyloid plaques occurs by the abnormal proteolysis of amyloid precursor protein, resulting in the formation of β amyloid peptides which further aggregates and results in the formation of oligomers, protofibrils, fibrils, and plaques. The complexity in understanding the aggregation process has provided avenues for identifying potential targets against amyloid toxicity in the treatment of AD. The therapeutic approach mainly focuses on reducing the toxicity by halting the β amyloid fibril formation. Besides conventional medicine, several naturally available compounds were shown to reduce the toxicity of amyloid plaques in the current scenario. This review provides a comprehensive account on recent updates of FDA-approved and naturally available compounds against toxicity of amyloid peptides and plaques both in vitro and in vivo.
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