Ogunrinola, Oluwaseyi2025-04-282025-04-282025-04-28http://hdl.handle.net/10393/50384https://doi.org/10.20381/ruor-31056Interaction between peptides and polyphenols, yielding peptide-polyphenol complexes, spontaneously occurs in most food systems, and is known to have an impact on sensory, functional, and nutraceutical properties of the food products. A better understanding of peptide-phenolic compound interactions would help to control the functional properties of peptides in food products during processing, transportation, and storage. Furthermore, it is necessary to understand the binding mechanism between polyphenols and peptides, which is useful for the development of peptides as delivery systems for insoluble polyphenols in the functional foods formulation. Thus, the understanding of the binding mechanism between polyphenols and peptide would be essential to evaluate the bioavailability of polyphenols. Moreover, a rational design of polyphenol-peptides particles would ensure a positive contribution to food quality, protein nutrition, and delivery of a health-relevant dose of polyphenols to the gastrointestinal tract. Hence, the polyphenols-proteins interactions and the impact of the inhibition of peptide activities by polyphenols are two key themes which are fundamental to draw attention to the importance of polyphenols. For all the reasons cited above, an insight into the in vitro and in vivo aspect of the peptide-polyphenols interactions and about an interesting impact of the antioxidant activities is the purpose of this work. The results indicated a clear antagonistic interaction between Phe-Cys and quercetin in vitro, with the peptide reducing the free radical scavenging ability of quercetin. The data suggest that molecular interactions, such as π-π stacking between the phenylalanine residue of the peptide and the aromatic rings of quercetin, limit the accessibility of quercetin's hydroxyl groups, which are essential for its antioxidant activity. Furthermore, dynamic light scattering analysis showed that the formation of peptide-quercetin complexes did not significantly alter particle size but likely contributed to the reduced antioxidant capacity observed in vitro. To complement the in vitro findings, an in vivo C. elegans model was employed to investigate the effects of these peptide-quercetin mixtures under oxidative stress induced by juglone, a known prooxidant. Despite the antagonistic in vitro results, the in vivo experiments demonstrated that the mixtures, particularly quercetin and the quercetin-peptide combination, significantly extended the lifespan of C. elegans by reducing reactive oxygen species (ROS) levels. These findings suggest that while the peptide-quercetin interactions reduce antioxidant efficacy in vitro, they still confer protective benefits against oxidative stress in a biological system. Molecular docking simulations further elucidated the interactions between Phe-Cys and quercetin, confirming the presence of π-π stacking and hydrogen bonding, which likely contributed to the observed reduction in antioxidant activity. The study highlights the complex nature of peptide-quercetin interactions, where antagonistic effects in vitro do not necessarily translate to reduced biological efficacy in vivo. Overall, this research provides new insights into the molecular mechanisms of peptide-quercetin interactions, with implications for the development of antioxidant formulations in food and nutraceutical applications. While the antagonistic effects observed in vitro present challenges, the positive in vivo results underscore the potential of peptide-quercetin mixtures in mitigating oxidative stress and promoting health.enPeptidesQuercetinAntioxidantC. elegansAntagonisticInteractionThesis