Applications of Peptides

I. Cytokine-mimetic peptides

Using known receptors as targets, peptide libraries can be screened to identify cytokine-mimetic peptides that activate the same signaling pathways. Multiple studies have yielded functional mimetics of erythropoietin, thrombopoietin, nerve growth factor, and several interleukins. In growth-hormone research, many agents act on the ghrelin receptor (GHSR) as growth hormone secretagogues (GHS/GHRP), enhancing endogenous GH secretion. Although their amino-acid sequences differ from native cytokines, these peptides can reproduce similar biological activities while being small and easy to synthesize; many are in preclinical or clinical phases.

II. Antimicrobial peptides (AMPs)

Upon stimulation, insects can induce large amounts of cationic antimicrobial peptides; hundreds have been identified. In vitro and in vivo studies show broad-spectrum bactericidal activity, and some also display cytotoxicity against certain tumor cells. The antimicrobial peptide D from Bombyx mori shows promising application potential and can be produced at scale via genetic engineering. Numerous snake-venom–derived peptides with antimicrobial activity have also been identified, some of which inhibit Gram-positive or Gram-negative bacteria in experimental systems.

III. Cardiovascular-related small peptides

Various plant-derived small peptides exhibit antihypertensive, lipid-lowering, and antithrombotic effects and can serve as active ingredients in drugs or functional foods. For example, soy-derived bioactive peptides can be absorbed in the small intestine and have been reported to show antithrombotic, antihypertensive/antilipidemic, and anti-aging effects. Small peptides with potential cardiovascular benefits have also been isolated from ginseng, tea leaves, and ginkgo leaves.

IV. Other therapeutic peptide advances

• The synthetic peptide TP508 promotes angiogenesis and accelerates healing of deep skin wounds.
• The small peptide (RTR)₄ reduces corneal inflammatory cell infiltration after alkali burns, mitigating inflammation.
• Several screening-derived synthetic peptides inhibit osteoclast-mediated bone resorption, suggesting potential in disorders of bone metabolism.

V. Diagnostic peptides

Peptides are widely used as synthetic antigens in immunodiagnostics. Compared with native pathogen proteins, peptide antigens offer higher specificity, better controllability, and ease of manufacture, thereby reducing false negatives and nonspecific background. Existing peptide-antigen–based assays cover numerous viruses (hepatitis A/B/C/G viruses, HIV, human cytomegalovirus, herpes simplex virus, rubella virus), bacteria (e.g., Treponema pallidum for syphilis; pathogens associated with Lyme disease), and parasites (cysticercosis, trypanosomes), as well as rheumatoid-related autoantibodies. The peptides used are typically derived from immunodominant regions of the relevant pathogen proteins, with some de novo sequences obtained via peptide-library screening.

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