Food-derived antihypertensive peptides have attracted increasing attention in functional foods for health promotion, due to their high biological activity, low toxicity and easy metabolism in the human body. Angiotensin converting enzyme (ACE) is a key enzyme that causes the increase in blood pressure in mammals. However, few reviews have summarized the current understanding of ACE inhibitory peptides and their knowledge gaps. This paper focuses on the food origins and production methods of ACE inhibitory peptides. Compared with conventional methods, the advanced technologies and emerging bioinformatics approaches have recently been applied for efficient and targeted release of ACE inhibitory peptides from food proteins. Furthermore, the transport and underlying mechanisms of ACE inhibitory peptides are emphatically described. Molecular modeling and the Michaelis-Menten equation can provide information on how ACE inhibitors function. Finally, we discuss the structure-activity relationships and other bio-functional properties of ACE inhibitory peptides. Molecular weight, hydrophobic amino acid residues, charge, amino acid composition and sequence (especially at the C-terminal and N-terminal) have a significant influence on ACE inhibitory activity. Some studies are required to increase productivity, improve bioavailability of peptides, evaluate their bio-accessibility and efficiency on reducing blood pressure to provide a reference for the development and application of health products and auxiliary treatment drugs.

The present study aimed to prepare polysaccharides from the pomace of Polygonatum rhizome and characterize their structural features and biological activities. After hot water extraction and DEAE-52 cellulose fractionation, a neutral polysaccharide (PKP) was obtained with 91.85% sugars and 0.45% proteins. Structural characterization indicated that PKP contained a main fraction with a molecular weight of 4.634 × 10³ Da and was composed of →1)-β-D-Fruf-(2→ and →6)-β-D-Fruf-(2→ residues. PKP was a semi-crystalline polymer, and the Congo red assay suggested the presence of triple-helix structure in PKP. PKP exhibited moderate radical scavenging activity (including 15.55% inhibition of DPPH, 21.48% inhibition of ABTS, and 22.52% inhibition of ·OH) and could effectively protect MRC-5 cells from H₂O₂-induced oxidative damage at 0.01 mg/mL through inhibiting apoptosis, decreasing SA-β-galactosidase activity, and downregulating the expression levels of p16 and p53. Therefore, PKP could be used in functional foods and pharmaceuticals as an antioxidant. This study provides an attractive method for utilizing polysaccharides from waste materials.

This study demonstrates the feasibility of producing three polysaccharides (neutral LJP-1, acidic LJP-2 and acidic LJP-3) with significant in vitro and in vivo anti-inflammatory activities from the flowers of Lonicera japonica. The three polysaccharides differed in chemical composition, Mw distribution, glycosidic linkage pattern, functional groups and morphology. They exhibited excellent protective effects (in a dose-dependent manner) in lipopolysaccharide-injured RAW264.7 macrophages and CuSO₄-damaged zebrafish via reducing NO production and inhibiting the overexpressions of inflammation-related transcription factors, inflammatory proteins and cytokines in the NF-κB/MAPK signaling pathways. Their anti-inflammatory effects varied owing to their different molecular characteristics and chemical compositions. Overall, LJP-2 at 400 μg/mL was the most effective. LJP-2 consisted mainly of →5)-α-L-Araf (1→, →4)-α-L-GalpA (1→ and →2)-α-L-Rhap (1→ residues with terminal T-β-D-Glcp. Thus, honeysuckle flowers are good sources of anti-inflammatory polysaccharides, and precise fractionation enables the production of potent anti-inflammatory agents for the development of functional foods and healthcare products.