Abstract
Corn silk (CS) is an agro-by-product from corn cultivation. It is used in folk medicines in some countries, besides being commercialized as health-promoting supplements and beverages. Unlike CS-derived natural products, their bioactive peptides, particularly antioxidant peptides, are understudied. This study aimed to purify, identify and characterize antioxidant peptides from trypsin-hydrolyzed CS proteins. Purification was accomplished by membrane ultrafiltration, gel filtration chromatography, and strong-cation-exchange solid-phase extraction, guided by 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical cation (ABTS•+) scavenging, hydrogen peroxide scavenging, and lipid peroxidation inhibition assays. De novo sequencing identified 29 peptides (6–14 residues; 633–1518 Da). The peptides consisted of 33–86% hydrophobic and 10–67% basic residues. Molecular docking found MCFHHHFHK, VHFNKGKKR, and PVVWAAKR having the strongest affinity (−4.7 to −4.8 kcal/mol) to ABTS•+, via hydrogen bonds and hydrophobic interactions. Potential cellular mechanisms of the peptides were supported by their interactions with modulators of intracellular oxidant status: Kelch-like ECH-associated protein 1, myeloperoxidase, and xanthine oxidase. NDGPSR (Asn-Asp-Gly-Pro-Ser-Arg), the most promising peptide, showed stable binding to all three cellular targets, besides exhibiting low toxicity, low allergenicity, and cell-penetrating potential. Overall, CS peptides have potential application as natural antioxidant additives and functional food ingredients.
Highlights
IntroductionCorn silk (Stigma maydis) (CS) is the thread-like style at the top of an ear of corn
The >3 kDa fraction exhibited stronger antioxidant activity than the
Our results are concordant with previous observations on the antioxidant activities of the UF fractions of fennel seed hydrolysate [34]
Summary
Corn silk (Stigma maydis) (CS) is the thread-like style at the top of an ear of corn. CS is discarded as an agricultural by-product worldwide, the value of CS as an herbal remedy has been recognized in the traditional medicines of some countries [1]. CS health supplements and CS-based tea are available to consumers. CS is rich in flavonoids, which are responsible for some bioactivities of CS, such as antioxidant, anti-fatigue, and anti-hyperlipidemic [1]. In contrast to natural product exploration, the identification and characterization of CS-derived bioactive peptides are limited. CS consists of 17.6% of crude proteins by dry weight [1], it may be a potential
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