Ameliorating effects of ethyl acetate fraction from onion (Allium cepa L.) flesh and peel in mice following trimethyltin-induced learning and memory impairment

- Both EOF and EOP effectively improved TMT-induced cognitive deficits in ICR mice.
- All EOF and EOP significantly increased SOD activity in the brain of TMT mice.
- Both EOF and EOP also efficiently reduced AChE activity, GSSG, and MDA levels.
- Quercetin-4′-glucoside and quercetin were analyzed as main phenolics of EOP.
- Isorhamnetin-4′-glucoside and quercetin-4′-glucoside were identified in EOF.

The anti-amnesic effects of onion (Allium cepa L.) flesh (OF)1 and peel (OP)2 on trimethyltin (TMT)3-induced learning and memory dysfunction were investigated to confirm learning and memory function. The inhibitory effect against cellular acetylcholinesterase (AChE)4 showed that the EtOAc fraction of OP (EOP5, IC50 value = 37.11 μg/mL) was higher than the EtOAc fraction of OF (EOF6, IC50 value = 433.34 μg/mL). The cognitive effects in ICR mice were also evaluated using Y-maze, passive avoidance, and Morris water maze tests. After the behavioral tests, AChE activity (control = 100%, TMT = 128%, EOF 20 = 108%, EOP 10 = 104%, and EOP 20 = 98%), superoxide dismutase (SOD)7 activity, oxidized glutathione (GSSG)8/total glutathione (GSH)9 and malondialdehyde (MDA)10 production were examined. These results indicate that both EOF and EOP improved learning and memory function. The main compounds of the EOF and EOP were analyzed by Q-TOF UPLC/MS, and the results were as follows: The EOF (quercetin and quercetin-4′-glucoside) and the EOP (quercetin-4′-glucoside and isorhamnetin-4′-glucoside). Consequently, our results suggest that both EOF and EOP could be efficacious in improving cognitive function through AChE inhibition and antioxidant activity in mice brains.