Protective Effect of Acmella Ciliata Extract and Spilanthol in Streptozotocin-induced Sporadic Alzheimer's Disease Mouse Model: Possible Involvement of the of Decreased Oxidative Stress by Activating TRPV1 Receptors

Abstract

This study investigated the effect of Acmella ciliata extract on memory impairment and oxidative stress dysfunction in the brain after intracerebral (i.c.v.) administration of 0.5 mg/kg streptozotocin (STZ) twice within 48 h in mice. Animals received orally treatment with ethanolic extract (50–150 mg/kg), hexane fraction (100 mg/kg) galantamine (40 mg/kg) and spilanthol (10 mg/kg), an alkamide isolated from the hexane fraction for 15 days. They were subjected to memory tests, inhibitory prevention (IAT) and the new object recognition tests (NOR). Experiments were performed with the animals' brains to evaluate the activity of catalase (CAT), superoxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (GPX), glutathione reductase (GR) and glutathione-S-transferase (GST) enzymes and to estimate malondialdehyde (MDA) concentration. We found that the treatments prevented STZ-induced memory loss, assessed by the IAT and NOR. Biochemical analysis revealed that STZ significantly increased levels of MDA and depleted (GSH) in mice’s brain. The extract decreased oxidation, as evidenced by a significant decrease in MDA and an increase in the antioxidant markers levels in mice treated with STZ. The positive effects of plant extract and fraction on STZ-induced memory deficits appear to be related to spilanthol and its activity on TRPV1 receptors, since pretreatment with capsazapine promotes the reversal of these effects. The results together demonstrate the beneficial effects of A. ciliata and spilanthol in preventing memory impairment, oxidative stress and dysfunction caused by STZ in mice. Therefore, there is a potential of this plant and its main compound spilanthol in the treatment of neurodegenerative disorders.