Bioactive peptides, specific protein fragments with positive health effects, are gaining traction in drug development for advantages like enhanced penetration, low toxicity, and rapid clearance. This comprehensive review navigates the intricate landscape of peptide science, covering discovery to functional characterization. Beginning with a peptidomic exploration of natural sources, the review emphasizes the search for novel peptides. Extraction approaches, including enzymatic hydrolysis, microbial fermentation, and specialized methods for disulfide-linked peptides, are extensively covered. Mass spectrometric analysis techniques for data acquisition and identification, such as liquid chromatography, capillary electrophoresis, untargeted peptide analysis, and bioinformatics, are thoroughly outlined. The exploration of peptide bioactivity incorporates various methodologies, from in vitro assays to in silico techniques, including advanced approaches like phage display and cell-based assays. The review also discusses the structure–activity relationship in the context of antimicrobial peptides (AMPs), ACE-inhibitory peptides (ACEs), and antioxidative peptides (AOPs). Concluding with key findings and future research directions, this interdisciplinary review serves as a comprehensive reference, offering a holistic understanding of peptides and their potential therapeutic applications.

Arimisia annua L. is an important anticancer herb used in traditional Chinese medicine. The molecular basis underpinning the anticancer activity is complex and not fully understood, but the herbal polysaccharides, broadly recognised as having immunomodulatory, antioxidant and anticancer activities, are potential key active agents. To examine the functions of polysaccharides from A. annua, their immunomodulatory and antioxidant potentials were evaluated, as well as their structural characterization. The water-soluble polysaccharides (AAPs) were fractionated using size-exclusion chromatography to obtain three dominant fractions, AAP-1, AAP-2 and AAP-3, having molecular masses centered around 1684, 455 and 5.8kDa, respectively. The antioxidant potentials of the isolated polysaccharides were evaluated by measuring radical scavenging activities against DPPH^● (2,2-diphenyl-1-picrylhydrazyl radical), ABTS^●+ (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid radical ion), and the OH^● (hydroxyl radical). AAP-1 displayed high antioxidant activities against these radicals, which were 68%, 73% and 78%, respectively. AAP-2 displayed lower scavenging activities than the other two fractions. Immunostimulatory activities of AAPs were measured using mouse macrophages. The three polysaccharide fractions displayed significant antioxidant activities and stimulated the production of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). AAP-1 showed significant immunostimulatory activity (16-fold increase in the production of IL-6 compared to the control and 13-fold increase in the production of TNF-α) with low toxicity (>60% cell viability at 125 μg/mL concentration). Preliminary structural characterization of the AAPs was carried out using gas chromatography (GC) and FTIR techniques. The results indicate that AAP-1 and AAP-2 are pyranose-containing polysaccharides with β-linkages, and AAP-3 is a β-fructofuranoside. The results suggest that these polysaccharides are potential candidates for immunotherapy and cancer treatment.

Lupin is an undervalued legume despite its high protein content with known health benefits. In this research, Australian blue lupin protein was isolated and hydrolysed enzymatically to produce bioactive peptides with a view to assess their potential for nutraceutical and therapeutic applications. Pepsin, pancreatin and flavourzyme were used to enzymatically hydrolyse blue lupin protein, and the hydrolysates were subjected to molecular weight cut‐off (MWCO) fractionation. Measurement of biological activities led to the identification of angiotensin converting enzyme (ACE) inhibitory fractions in the molecular weight range of 2–3 and 3–5 kDa. For the most active fractions in this range, the ACE inhibitory activities were very significant with IC₅₀ values from 450 to 600 μg/ml. Blue lupin protein‐derived MWCO fractions were significantly active against Gram‐positive bacteria and only a little inhibition was observed against Gram‐negative bacteria. Pancreatin hydrolysed fractions showed the best antimicrobial activities with several fractions exhibiting ≥85% inhibition against Bacillus cereus and Staphylococcus aureus. These properties reveal the potential of lupin protein hydrolysates for developing antihypertensive and host defence agents. In order to demonstrate the potential of isolated blue lupin protein in food industry, functional properties including water and oil absorption capacity, gelling properties, solubility and emulsifying properties were evaluated and found to be extremely suitable for developing functional foods with enhanced health benefits.

Lupin is a major rotational crop produced abundantly in Australia. Three varieties of sweet lupins are grown in Australia depending on soil types and climatic conditions; these are white lupin (Lupinus albus), blue lupin (Lupinus angustifolius), and yellow lupin (Lupinus luteus). In this study, polysaccharides from the three lupin species have been extracted with hot water and a range of their biological activities investigated. The antioxidant activities of lupin polysaccharides have been measured in terms of ABTS^•+ radical and hydroxyl radical scavenging activities, and their affinity to chelate with iron. Immune-enhancing power of the lupin polysaccharides was examined by measuring their capacity to stimulate the macrophages (RAW 264.7) to release TNF-α and nitric oxide. The prebiotic activities were determined against the beneficial probiotics such as Lactobacillus rhamnosus DR20, Lactobacillus acidophilus LAFTI L10, Bifidobacterium lactis DR10, and Bifidobacterium animalis BB-12. Polysaccharides from the three lupin species have exhibited significant antioxidant, immunostimulatory, and prebiotic activities. The results demonstrated that blue lupins displayed the best activities, and therefore are expected to possess high potential to be used as nutraceutical and functional ingredients with significant therapeutic value. FT-IR spectroscopic technique was employed for a preliminary structural characterization. Studies involving surface morphology and thermal behavior have indicated that the lupin polysaccharides are suitable for end product development.