Oxidative Stress Amelioration of Novel Peptides Extracted from Enzymatic Hydrolysates of Chinese Pecan Cake

Abstract

Pecan (Carya cathayensis) is an important economic crop, and its hydrolyzed peptides have been evidenced to reduce the effect of oxidative stress due to their antioxidant capacity. Hence, the protocols of ultrafiltration and gel filtration chromatography were established to obtain bioactive peptides from by-products of C. cathayensis (pecan cake). As measured by DPPH/ABTS radical scavenging, the peptides with less molecular weight (MW) possess higher antioxidant capacity. PCPH-III (MW < 3 kDa) presented higher radical scavenging capacity than PCPH-II (3 kDa < MW < 10 kDa) and PCPH-I (MW > 10 kDa) measured by DPPH (IC50: 111.0 μg/ mL) and measured by ABTs (IC50: 402.9 μg/mL). The secondary structure and amino acid composition varied by their MW, in which PCPH-II contained more α-helices (26.71%) and β-sheets (36.96%), PCPH-III contained higher ratios of β-turns (36.87%), while the composition of different secondary of PCPH-I was even 25 ± 5.76%. The variation trend of α-helix and random experienced slightly varied from PCPH-I to PCPH-II, while significantly decreased from PCPH-II to PCPH-III. The increasing antioxidant capacity is followed by the content of proline, and PCPH-III had the highest composition (8.03%). With regard to the six peptides identified by LC-MS/MS, two of them (VYGYADK and VLFSNY) showed stronger antioxidant capacity than others. In silico molecular docking demonstrated their combining abilities with a transcription factor Kelch-like ECH-associated protein 1 (Keap1) and speculated that they inhibit oxidative stress through activating the Keap1-Nrf2-ARE pathway. Meanwhile, increased activity of SOD and CAT—antioxidant markers—were found in H2O2-induced cells. The residue of tyrosine was demonstrated to contribute the most antioxidant capacity of VYGYADK and its position affected less. This study provided a novel peptide screening and by-product utilization process that can be applied in natural product developments.

Preparation process optimization and evaluation of bioactive peptides from Carya cathayensis Sarg meal

“…Different exposure degree of side chain groups among CMPs may lead to distinct abilities although amino acid composition is similar, explaining results we obtained. Moreover, Zhang et al (2022) obtained CM-derived peptides by ultrafiltration and gel filtration chromatography, and found that the substances with MW lower than 3 kDa have the highest antioxidant capacity. Six peptides were next identified including FYSLHTF, VLFSNY, SSGHTLPAGV, VYGYADK, TFQGPPHG, YTPEYQTK.…”

From In Silico to a Cellular Model: Molecular Docking Approach to Evaluate Antioxidant Bioactive Peptides

“…Ile (Ile 559) is the only hydrophobic amino acid that is significantly involved in peptide binding. Taking into consideration the single peptide sequence, it was suggested that Pro, Gly, Ala, Val, and Leu are generally an essential presence in antioxidant peptides [ 67 , 68 , 69 , 91 ]. However, it has been discovered that a vast number of peptides with a heterogenous composition can bind to Keap1.…”

Research Progress on the Preparation and Function of Antioxidant Peptides from Walnuts

“…The Nrf2 transcription factor is a potential neurological therapeutic target [68,69]. In research studies on walnut antioxidant peptides, it is often used along with Keap1 and OH-1 [70][71][72][73].…”

“…The expression of these downstream genes can avoid alterations in cellular functions and enhance cellular resistance to oxidative stress. Studies have shown that walnut-derived peptides can inhibit the Keap1-Nrf2-ARE pathway by activating the binding of these peptides to Keap1 and releasing Nrf2 [70] (Figure 4). Simultaneously, the activity of the antioxidant markers (SOD and CAT) increases in hydrogen peroxide-induced cells.…”