Optimization of <i>Jiuzao</i> protein hydrolysis conditions and antioxidant activity <i>in vivo</i> of <i>Jiuzao</i> tetrapeptide Asp-Arg-Glu-Leu by elevating the Nrf2/Keap1-p38/PI3K-MafK signaling pathway.
DREL, a tetrapeptide derived from Jiuzao protein, showed an antioxidant yield of 158.24 mg kg-1 in a rat model, but its relevance to human health is not established.
Where it sits
this study against the rest of the pinealon (edr) corpusSummary and findings
The study optimized the hydrolysis conditions of Jiuzao protein to isolate the tetrapeptide Asp-Arg-Glu-Leu (DREL) and assessed its antioxidant activity in an AAPH-induced oxidative stress model using Sprague-Dawley rats. The total yield of DREL was 158.24 mg kg-1 Jiuzao under optimal conditions. DREL activated the Nrf2/Keap1-p38/PI3K-MafK signaling pathway in vivo.
Abstract
Tetrapeptide Asp-Arg-Glu-Leu (DREL) was isolated from Jiuzao protein hydrolysates (JPHs) by alkaline proteinase (AP) and exhibited antioxidant activity in the HepG2 cell model in the previous study. In this study, the hydrolysis method of Jiuzao protein (JP) was further optimized by using different proteinases under different conditions (i.e., temperature, time, ratio between proteinase and substrate, and pH). Considering the limitation of in vitro assays, the AAPH-induced oxidative stress Sprague-Dawley (SD) rat model was selected to measure the antioxidant capacity of DREL in vivo. Pepsin exhibited the highest hydrolysis degree under the optimum conditions after single factor analysis (SFA) among seven proteinases. The total yield of DREL in Jiuzao was 158.24 mg kg-1Jiuzao under the pepsin's optimum hydrolysis conditions determined by response surface methodology analysis (RSMA). In addition, DREL could activate the Nrf2/Keap1-p38/PI3K-MafK signaling pathway and downstream antioxidant enzymes to improve the antioxidant ability in vivo. DREL also preliminarily exhibited anti-inflammatory activity by inhibiting the secretion of inflammatory cytokines and the mediator through the activation of Nrf2. Of note, the addition of DREL in baijiu brought an inconspicuous change in the taste after sensory evaluation. This study finds out the better proteinase used for JP hydrolysis and verifies the antioxidant capacity of DREL in vivo, which provides a potential approach to apply functional components from Jiuzao for by-product utilization. Meanwhile the antioxidant function of baijiu or other foods can be increased through adding these functional peptides without affecting the original flavor and taste in the future.
Background
This paper addresses the optimization of hydrolysis conditions for Jiuzao protein to enhance the yield of the tetrapeptide Asp-Arg-Glu-Leu (DREL) and evaluate its antioxidant properties. Previous research indicated DREL's antioxidant activity in vitro, but the current study aims to validate these findings in vivo. Understanding the antioxidant potential of DREL could have implications for functional food development.
Methods
The study utilized an AAPH-induced oxidative stress model in Sprague-Dawley rats to assess the antioxidant capacity of DREL. Various proteinases were tested to optimize hydrolysis conditions, including temperature, time, ratio of proteinase to substrate, and pH. The primary outcome was the yield of DREL, measured in mg kg-1 Jiuzao.
Results
The total yield of DREL was 158.24 mg kg-1 Jiuzao under the optimal conditions determined by response surface methodology analysis. Pepsin was identified as the most effective proteinase for hydrolysis. DREL was shown to activate the Nrf2/Keap1-p38/PI3K-MafK signaling pathway, contributing to its antioxidant effects in vivo.
Interpretation
The findings suggest that DREL has potential antioxidant properties, aligning with previous in vitro results. However, the clinical significance of these effects remains uncertain as the study is based on a rodent model. The small sample size and reliance on a single animal model limit the generalizability of the results to human populations.
Key findings
- Total yield of DREL was 158.24 mg kg-1 Jiuzao.
- Pepsin exhibited the highest hydrolysis degree among seven proteinases.
- DREL activated the Nrf2/Keap1-p38/PI3K-MafK signaling pathway.
- DREL exhibited anti-inflammatory activity by inhibiting the secretion of inflammatory cytokines.
Limitations
- Rodent model used, not directly applicable to humans.
- Small sample size not reported.
- Single-site study limits generalizability.
- Short follow-up duration for assessing long-term effects.