Different cultures worldwide have attributed particular healing abilities to various plants for a long time. After decades of studies, research has demonstrated that their bioactivity is associated mainly with the presence of natural products, including short protein fragments known as peptides. These molecules may occur naturally in plants or be generated from plant protein through enzyme hydrolysis. In recent years, a growing body of evidence has linked plant-derived peptides to diverse biological activities, underscoring the importance of their structural and physicochemical features in determining functionality. Compared with peptides of animal or microbial origin, plant peptides stand out for their high abundance in sustainable sources, low allergenic potential, and distinctive structural traits- such as enrichment in hydrophobic and aromatic residues- that influence their stability, mechanisms of action, and biological functions. This review compiles and analyzes current literature to provide insights into how amino acid composition, secondary structure, net charge, and hydrophobicity influence peptide bioactivity. In addition, the review highlights the mechanisms of action most frequently described for plant peptides. Finally, the article discusses the current landscape and prospects of peptide-based drugs.

Reactive oxygen species are produced as part of the cellular metabolism. However, lifestyle can promote an excess in their concentration. Free radicals react with DNA, promoting the appearance of cancer cells. Therefore, natural antioxidants have been suggested as an alternative to prevent this disorder. Peptides are protein fragments that have been produced from various plants. In previous work, Moringa oleifera leaf peptides (MOPHs) with antioxidant potential were generated and identified. However, the spectrophotometric methods used to evaluate their antioxidant activity do not fully reflect its potential. In this work, the antioxidant activity of MOPHs was assessed by the ferric reducing antioxidant power assay (FRAP) and cellular antioxidant activity method on the human colon cancer cell line Caco-2. Also, their antiproliferative activity was evaluated. The MOPHs exhibited a FRAP activity of 1435 µmol TE/g, and at 500 µg/mL; the peptides did not show a cytotoxic effect on healthy colon CCD-18Co cells. Moreover, the MOPHs increased Caco-2 antioxidative activity to a greater extent by 73.45% and 83.62% at 250 and 500 µg/mL, respectively. Regarding cellular proliferation, the MOPHs inhibited it by 78.19% and 90.20% at 200 and 500 µg/mL, respectively. These findings highlight the potential of Moringa oleifera leaf peptides as functional ingredients with significant health benefits, demonstrating antioxidant and antiproliferative properties.