Comparative antioxidant activity and potential neuroprotective of Zingiber officinale Roscoe extracts collected from Thailand and Malaysia against glutamate-induced oxidative neurotoxicity

Ginger (Zingiber officinale Roscoe, Zingiberaceae) is considered a chemopreventive agent possessing antioxidant, anti-cancer, and neuroprotective activities. Alzheimer’s disease is aggravated overtime due to oxidative stress causing neurotoxicity. In this study, we investigated whether environmental factors and polarity of solvents should be considered as effectors of the neuroprotective potential of eight prepared extracts, from Thai and Malaysian ginger. The total phenolic and flavonoid contents varied from 23.48 to 123.61 mg/g and from 2.11 to 5.62 mg/g of dry extract, respectively. DPPH and ABTS assays revealed the values ranged from 2.44 to 83.66% and from 10.45 to 94.20%, respectively. As co-treatment HT-22 cells with varied concentrations of ginger and glutamate (5mM) was carried out, ginger restored cell viability by 0.25 to 17.67% comparing to glutamate alone. H2DCFDA assay showed ROS reduced from 10 to 46% comparing to glutamate-treated cells. The aqueous extract showed the higher activity in Thai ginger, whereas the ethanol extract had higher function in Malaysian ginger. The geographical factor and polarity of solvents made a significant difference in the protection provided to the HT22 cells. The ginger considered as a neuroprotective agent against glutamate-induced neurotoxicity in HT-22 cells, via an attenuated intercellular ROS accumulation mechanism.