GSK-3beta inhibitory effects of 6-gingerol and 6-shogaol help to the recovery of SHSY-5Y cells after amyloid beta1–42 oligomer or aggregate toxicity

BACKGROUND: GSK-3 , has been shown to regulate APP cleavage resulting in the increased production of A and the inhibition of the GSK-3 reduced the amyloid beta induced neurotoxicity in several studies. OBJECTIVE: This study was designed to investigate the GSK-3 inhibitory effects of 6-gingerol and 6-shogaol the major components ofZingiber officinale could be able to recover the SHSY-5Y cells from Amyloid beta 1–42 oligomer and aggregate toxicity. METHODS: SHSY-5Y (ATCC; CRL-2266) cells were maintained in Dulbecco’s modified eagle medium (DMEM, Gibco) containing 10% fetal calf serum, 100 U/mL penicillin, 50 g/mL streptomycin, at 37◦C and 5% CO2 in a humidified incubator. Cells were transferred to sterile 96-well e-plates at 5× 104 cells per well and followed real time for 78 hours via Xcelligence system. Ferulic acid was used as a positive control as a GSK-3 inhibitor at 4 M dose and 6-gingerol and 6-shogaol were applied to the cells at 0.01 M, 0.1 M, 1 M, 10 M, 100 M doses/50 L with or without -Amyloid 1–42 oligomers or aggregates. GSK-3 activity was determined by Kinase-Glo assay. RESULTS: Both the amyloid beta aggregates and the oligomers had cytotoxic effect on SHSY-5Y cells followed by the real time cell analyzer system. 6-gingerol and 6 shogaol inhibited the GSK-3 enzyme up to % 20 levels in a dose dependent manner until 1 M. However, parallel with the reduction of the inhibition for 6-shogaol over 1 M, showed a toxicity itself on SHSY-5Y cells, whereas 6-gingerol did not show any cytotoxic effect at any doses applied. CONCLUSIONS: 6-gingerol and 6-shogaol increased the cell viability followed in a real time manner after around 24 hours than the amyloid beta aggregate or oligomer toxicity as much as the ferulic acid could. Furthermore these effects supported the GSK-3 inhibitory effects of both compounds at low doses up to 1 M. These results reveal that 6-gingerol and 6-shogaol the major components of Zingiber officinale help to recovery from amyloid beta toxicity which might further be investigated by clinical trials.