Neuroprotective effects of alkaloids from Piper longum in a MPTP-induced mouse model of Parkinson’s disease

Abstract

Context: Alkaloids of Piper longum L. (Piperaceae) (PLA) include piperine and piperlonguminine. Piper longum and piperine have multiple biological properties including antioxidant activity.

Objective: The present study investigated the neuroprotective effects of PLA in a MPTP-induced mouse model of Parkinson’s disease.

Materials and methods: PLA was prepared by extracting the dry seed of P. longum using 85% ethanol. Adult male C57BL/6 mice were divided into eight groups of 12 rats each. Experimental and control groups received an equivalent volume of saline, 0.5% CMC-Na, and 0.1% Tween 80, treated groups received oral PLA (30, 60, and 120 mg/kg), other groups treated with piperine (60 mg/kg) or Madopar (50 mg/kg). The PLA prevention group (PLA-Pr) administrated PLA (120 mg/kg) for 1 week before MPTP challenged. Except for the PLA-Pr group, others were treated for seven consecutive weeks. Parkinson’s disease was induced by injecting MPTP intraperitoneally (25 mg/kg) twice weekly for five consecutive weeks. Dopaminerigic (DA) neurons and their metabolism were detected by UFLC-MS/MS. Tyrosine hydroxylase (TH)-immunohistochemistry assay and Western blotting were performed. The antioxidant enzymatic levels were determined by kit-based assays.

Results: The LD₅₀ value of PLA was determined at 1509 mg/kg of body weight. PLA (60 mg/kg) can significantly increase total movement time and distance (p < 0.05), increase levels of DA (p < 0.05) and DOPAC (p < 0.05), increase glutathione (GSH) level and superoxide dismutase (SOD) activity (p < 0.05), and decrease the lipid peroxidation of malondiadehycle (MDA) (p < 0.05) in PLA-treated groups as compared with the control group.

Discussion and conclusion: Our results indicate that PLA possesses neuroprotective effects and has ameliorative properties in dopaminergic neurons.

• Antioxidants
• lipid peroxidation
• oxidative stress
• Piperaceae

Declaration of interest

The authors report that they have no conflicts of interest. The authors alone are responsible for the content and writing of this article. This work was supported by National Natural Science Foundation of China (Nos. 81073016 and 81473333), Funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality (KM 201010025013, PHR201008402, and PHR 200907113) and Key Laboratory of brain diseases in Beijing (2014SJZS04).