Neuroprotective effect of Amaranthus lividus and Amaranthus tricolor and their effects on gene expression of RAGE during oxidative stress in SH-SY5Y cells.

Amaranthus plants, or spinach, are used as food sources worldwide. Amaranthus leaves are rich in antioxidant compounds, which act as free radical scavengers. Oxidative stress caused by the aberrant production of reactive oxygen species (ROS) represents an important mechanism for neuronal dysfunction and cell loss in different neurodegenerative disorders. The neuroprotective effects of antioxidant-containing plants have been extensively demonstrated in different models of neurotoxicity. However, few studies have investigated the antioxidant properties of Amaranthus extracts and their effect on the nervous system. In the present study, the leaves of Amaranthus lividus and Amaranthus tricolor were extracted using petroleum ether, dichloromethane, and methanol. Results indicated that antioxidant activities were the highest in methanol extracts from both kinds of Amaranthus leaves. In addition, oxidative stress was induced in human neuroblastoma cell lines (SH-SY5Y) by using H2O2. Intracellular oxidative stress, cytotoxicity, and gene expression of RAGE were then determined. In vitro results demonstrated that pretreatment with A. lividus and A. tricolor extracts can significantly decrease cell toxicity and intracellular ROS production in SH-SY5Y cells. Interestingly, the extracts also significantly downregulated the expression of oxidative stress genes such as HMOX-1, RAGE, and RelA/ NF-κB. Our results suggested that Amaranthus leaves may be useful for reducing oxidative stress and may be beneficial for age-related diseases and neurodegenerative disorders.