Neuroprotective and Memory-Enhancing Effects of Antioxidant Peptide From Walnut (Juglans regia L.) Protein Hydrolysates

Abstract

Peptides have been reported to possess interesting biological properties. The present study was designed to evaluate neuroprotective and memory-enhancing effects of antioxidant peptide from walnut (Juglans regia L.) protein hydrolysates. The neuroprotective effect of walnut peptide (WP) against oxidative stress on PC12 cells was evaluated. And zebrafish was used as the model to corroborate the effect. Its effect on learning and memory of mice using the Morris water maze and the step-down passive avoidance tests were performed. Moreover, the acute toxicity of WP was carried out to assess its safety profile. It was found that WP was able to suppress H 2 O 2 -induced cell death in PC12 cells. In the zebrafish model, WP had an obvious neuroprotective effect, and the ratio reached 42% at 222 µg/mL. The mechanism study revealed that WP could inhibit the activity of caspases 3/7 and 8, reduce the mRNA expression levels of Bax and glial cell line-derived neurotrophic factor, and improve the mRNA expression level of brain-derived neurotrophic factor significantly. Besides, the treatment of mice with WP shortened the escape latency and exhibited much longer target time and more crossing times significantly, compared with untreated control groups in the Morris water maze test. Similarly, the step-down passive avoidance test showed that WP could ameliorate memory impairments. The administrated dose (20.1 g/kg body weight [BW]) did not produce mortality or treatment-related adverse effects with regard to BW, general behavior, or relative organ weights of the tested male and female mice. The current results indicated that WP could exert neuroprotective effect, and attenuated learning and memory impairments. These ameliorating effects of WP may be useful for treatment of memory impairment in Alzheimer's and its related diseases.

Walnut (Juglans regia L.) Oligopeptide Effects on Enhancing Memory, Cognition and Improving Sleep Quality in Teenagers and Elderly People in a Randomized Double-Blind Controlled Trial

“…21 Our previous study also demonstrated that WO has enhancing memory effects by antioxidative stress and increases the brain-derived neurotrophic factor level. 16 In this study, we observed that people taking WO for 90 days can increase scores of intelligence quotient (IQ) in teenagers and elderly people. In addition, the students’ academic performance was improved.…”

“…16 Besides, the Morris water maze and Step-Down tests both showed that WO ameliorated memory impairments in scopolamine-, sodium nitrite- or ethanol-induced mice model. 16 With the modern acceleration in the pace of life, increasingly more people are afflicted by insomnia. Insufficient sleep or poor sleep quality can affect physical functions.…”

“…16 In the zebrafish model, WO showed a neuroprotective effect. 16 Besides, the Morris water maze and Step-Down tests both showed that WO ameliorated memory impairments in scopolamine-, sodium nitrite- or ethanol-induced mice model. 16 With the modern acceleration in the pace of life, increasingly more people are afflicted by insomnia.…”

“…15 Furthermore, our previous study indicated that WO protected PC12 cells (rat adrenal medulla pheochromocytoma) against H 2 O 2 -induced oxidative stress. 16 In the zebrafish model, WO showed a neuroprotective effect. 16 Besides, the Morris water maze and Step-Down tests both showed that WO ameliorated memory impairments in scopolamine-, sodium nitrite- or ethanol-induced mice model.…”

Cellular antioxidant effect of bioactive peptides and molecular mechanisms underlying: beyond chemical properties

“…In the majority of cases, the common cell lines used include: human epithelial colorectal adenocarcinoma (Caco-2) (Zhang, Tong, et al, 2019;Tonolo et al, 2020), human liver carcinoma (HepG2) (Chen et al, 2019;Sun et al, 2019), human normal hepatoma (Chang) (Je et al, 2015;Ding et al, 2019), cervical adenocarcinoma (HeLa) (Ma et al, 2016;Mart ınez-Leo et al, 2019), human umbilical vein endothelial (HUVEC) (Liang et al, 2018;Xu et al, 2018), human neuroblastoma (SH-SY5Y) (Lee & Hur, 2019;Sheng et al, 2019), rat adrenal pheochromocytoma (PC12) (Lee & Hur, 2019;Liu et al, 2019) and mouse macrophage (RAW 264.7) (Saisavoey et al, 2016;Indiano-Romacho et al, 2019) cells. Also, the most common inductor of oxidative stress used in the above-mentioned studies was hydrogen peroxide (H 2 O 2 ), a reactive oxygen species (ROS), because it can rapidly diffuse across cell membranes and can trigger programmed cell death (Di Marzo et al, 2018).…”