Protective Effects Induced by Microwave-Assisted Aqueous Harpagophytum Extract on Rat Cortex Synaptosomes Challenged with Amyloid β-Peptide

Harpagophytum procumbens is a plant species that displays anti-inflammatory properties in multiple tissues. The iridoid glycosides arpagoside, harpagide, and procumbide appear to be the most therapeutically important constituents. In addition, harpagoside treatment exerted neuroprotective effects both in vitro and in vivo. Considering these findings, the aim of the present work is to explore the possible protective role of the previously described microwave-assisted aqueous extract of Harpagophytum on rat hypothalamic (Hypo-E22) cells, and in rat cortex challenged with amyloid β-peptide (1-40). In this context, we assayed the protective effects induced by Harpagophytum by measuring the levels of malondialdehyde (MDA), 3-hydroxykynurenine (3-HK), brain derived neurotrophic factor (BDNF), and tumor necrosis factor (TNF)-α, 3-hydroxy-kinurenine (3-HK). Finally, we evaluated the effects of Harpagophytum treatment on cortex levels of dopamine (DA), norepinephrine (NE) and serotonin (5-HT). Harpagophytum extract was well tolerated by Hypo-E22 cells and upregulated BDNF gene expression, but down-regulated TNF-α gene expression. In addition, the extract reduced amyloid β-peptide stimulation of MDA and 3-HK and blunted the decrease of DA, NE and 5-HT, in the cortex. In this context, our work supports further studies for the evaluation and confirmation of Harpagophytum in the management of the clinical symptoms related to Alzheimer’s disease.