Chronic neuralgia, visceral pain, anxiety stress, and drug addiction have long lacked safe and effective intervention targets. Traditional μ-opioids are prone to addiction and have a high risk of tolerance, while the κ-opioid receptor pathway has become a core research direction for next-generation analgesia and mood regulation. Dynorphin A (1-13) Acetate, with a purity ≥99.0%✨, is an endogenous 13-peptide κ-opioid receptor highly selective agonist acetate polypeptide raw material. Relying on its high κ receptor targeting, weak μ receptor activity, lack of significant addictiveness, and combined analgesic and anti-stress properties, it is widely used in the research and development of neuropharmacology, pain mechanisms, mental illness, and addiction intervention.
🧩 Basic linear 13-peptide acetate backbone
Dynorphin A (1-13) Acetate has the amino acid sequence Tyr-Gly-Gly-Phe-Leu-Arg-Arg-Ile-Arg-Pro-Lys-Leu-Lys・CH₃COOH, molecular formula C₇₄H₁₃₀N₂₃O₁₆, molecular weight 1603.06, and appears as a white lyophilized powder. Its purity is ≥99.0%, with single impurities ≤0.15%, moisture ≤4.0%, and endotoxin <0.1 EU/mg. It meets USP peptide raw material, EP pharmacopoeia, and cGMP research-grade peptide standards. The molecule consists of an N-terminal receptor core binding region, a middle arginine-rich basic region, a C-terminal flexible regulatory peptide segment, and an acetate salt-forming group. As a natural endogenous dynorphin active fragment, it exhibits higher stability and stronger κ-receptor selectivity compared to the full-length dynorphin, making it a benchmark molecule for research-grade opioid peptides.
The N-terminal Tyr-Gly-Gly-Phe-Leu pentapeptide sequence is the core functional region for activating the κ-opioid receptor. This conserved sequence is homologous to other endogenous opioid peptides. The phenolic hydroxyl group of tyrosine residues and the hydrophobic side chain of phenylalanine can precisely embed into the extracellular domain of the κ receptor, forming a stable network of hydrophobic interactions and hydrogen bonds. The 99.0% high-purity raw material is strictly controlled with amino acid deletions, oxidation, and deamination impurities ≤0.1%, and sequence integrity >99.5%. In vitro receptor binding tests show that its affinity for human κ-opioid receptors is much higher than that for μ and δ receptors, exhibiting excellent target selectivity and avoiding the addiction risks associated with off-target effects of traditional opioid peptides. Solid-phase peptide synthesis employs the Fmoc strategy, enabling precise sequence synthesis and acetate salt formation, resulting in highly consistent batch-to-batch stability.
The continuous arginine-rich region in the middle provides a strong positive charge, significantly improving the peptide's water solubility and enhancing its electrostatic adsorption to cell membranes, promoting molecular accumulation in central and peripheral pain neurons. High-density basic amino acids resist rapid hydrolysis by aminopeptidases and carboxypeptidases, significantly prolonging the half-life compared to short-chain opioid peptides. This allows for a longer duration of action in cerebrospinal fluid and tissue fluid, making it suitable for in vitro cell experiments and in vivo animal drug delivery studies.
The C-terminal flexible regulatory peptide can fine-tune the receptor activation conformation, reducing weak agonistic activity towards μ-opioid receptors and further enhancing κ receptor specificity. It also participates in regulating downstream G protein signaling pathway bias, preferentially activating the Gi/O protein inhibitory pathway, reducing tolerance and side effects mediated by the β-arrestin pathway, providing a structural basis for low-addiction analgesia. This flexible structure also allows the molecule to be adapted to various administration routes, maintaining stable efficacy with intraventricular, intrathecal, and subcutaneous administration.
The acetate salting group optimizes the peptide's solid-state stability and water solubility, neutralizes the peptide's basic charge, preventing aggregation and degradation during storage, and reduces the hygroscopicity of the lyophilized powder. After 6 months of accelerated stability testing at 40℃/75% RH, the purity decrease is <0.2%, allowing for long-term storage. The acetate form can also improve the dissolution rate of peptides in physiological buffer solutions, making it suitable for scientific research experiments such as cell incubation and animal drug administration.
🔧Targeting κ-opioid receptors to achieve multi-pathway physiological regulation
Dynorphin A (1-13) Acetate have a completely different mechanism of action from μ-receptor agonists such as morphine and fentanyl. Its core mechanism involves highly selective activation of central and peripheral κ-opioid receptors, inhibiting pain signal transduction, regulating dopamine and norepinephrine release, and exerting analgesic, anti-anxiety, anti-stress, and reward-inhibiting effects. It has no significant respiratory depression or addictive properties. Its 99.0% ultra-high purity ensures sequence integrity and salt stability, allowing for precise and controllable action along the target pathway, making it suitable for in-depth neuropharmacological mechanism research.
After administration, the peptide preferentially accumulates in pain- and emotion-regulating brain regions such as the dorsal horn of the spinal cord, the periaqueductal gray matter of the midbrain, the amygdala, and the hypothalamus. It specifically binds to κ-opioid receptors, activating the Gi/O protein signaling pathway, inhibiting adenylate cyclase activity, closing voltage-gated calcium channels, and opening potassium channels. This causes hyperpolarization of pain neurons, directly blocking the release of pain-inducing neurotransmitters such as substance P and CGRP, and effectively inhibiting the uptake of neuropathic pain and visceral pain signals.
At the central reward system level, this peptide can inhibit abnormal dopamine release in the mesolimbic system and downregulate reward circuit activity. Unlike the dopamine-increasing mechanism of μ-receptor agonists, it does not produce euphoria, thus avoiding drug addiction, tolerance, and dependence at the root. It can also reduce drug-seeking behavior for cocaine and opioids, demonstrating potential for addiction intervention.
By regulating the hypothalamus-pituitary-adrenal axis, it inhibits the secretion of corticotropin-releasing hormone, reduces cortisol levels, and exerts anti-anxiety, antidepressant, and chronic stress-relieving effects. It has a regulatory effect on post-traumatic stress disorder and chronic stress-related mood disorders, and can simultaneously improve comorbid emotional problems associated with pain.
In peripheral tissues, it can activate κ-receptors on dorsal root ganglia, joints, and intestinal mucosa, inhibiting the release of local inflammatory factors and reducing inflammatory and visceral pain. Simultaneously, it does not affect normal gastrointestinal motility, and peripheral side effects such as constipation and nausea are significantly lower than those of traditional opioids.
Long-term use does not induce rapid desensitization of κ-receptors. Stable analgesic and mood-regulating effects are maintained even after continuous administration, with no significant tolerance. It has almost no inhibitory effect on the cardiovascular and respiratory centers, and its safety is significantly superior to classic opioid analgesics, providing an ideal template for the development of novel analgesics.
💊Research tools for addiction research and neuroprotection
The primary use of Dynorphin A (1-13) Acetate in scientific research is as a selective agonist of the κ opioid receptor and a tool for studying addiction mechanisms. In drug dependence studies, this peptide is widely used to simulate the negative emotional state during withdrawal. In morphine-dependent rats, intraventricular injection of Dynorphin A (1-13) induced significant withdrawal-like symptoms and enhanced conditioned aversion. These effects could be reversed by κ antagonists, suggesting that overactivation of κ receptors is involved in the aversion component of opioid withdrawal. This finding provides a new target for developing drugs to treat drug dependence.
In pharmacological screening for antidepressants and anxiolytics, Dynorphin A (1-13) is widely used as a positive control. In the tail suspension test or forced swimming test, intraventricular or lateral ventricle injection of this peptide dose-dependently increases immobility time, mimicking a depressive-like phenotype. This depressive effect can be blocked by κ-receptor antagonists; therefore, many antidepressants targeting κ receptors use the effect of dynorphin A (1-13) as a benchmark for assessing the reliability of screening systems. In stress neurobiology, dynorphins are important mediators of stress responses. Chronic social frustration stress can upregulate dynorphin A expression in the hippocampus, driving social avoidance and anhedonia. This peptide is used in microdialysis or microinjection into specific brain regions to study the causal relationship of stress effects in specific brain regions.
In the field of neuroprotection, the role of Dynorphin A (1-13) Acetate is significantly controversial. Some literature reports that blocking κ receptors in cerebral ischemia models can reduce infarct volume, suggesting that the release of endogenous dynorphins exacerbates ischemic damage; however, other studies have shown that low-dose dynorphin A (1-13) protects neurons from hypoxic damage by inhibiting calcium influx and scavenging free radicals. This dual effect makes this peptide a "double-edged sword" in studying the mechanisms of stroke. In neurological injury models, Dynorphin A (1-13) Acetate is involved in the pathological process of secondary injury. Dynorphin expression is upregulated after spinal cord injury, and κ antagonists can improve motor function recovery. Therefore, this peptide has been used to study the pathophysiological role of the endogenous opioid system after spinal cord injury.
In a recent study in 2026, researchers used optogenetics combined with microinjection of dynorphin A (1-13) to depict how neurons expressing dynorphin in the nucleus accumbens integrate aversion signals. These findings provide important experimental evidence for understanding addiction and reward circuits, indicating that the application value of this peptide in neuroscience continues to grow.
🔭Stability Improvement and Central Delivery
The core challenges in the research applications of Lynorphin A (1-13) Acetate lie in the peptide's in vivo instability (extremely short half-life) and its delivery efficiency to the central nervous system. Replacing the glycine at the second or third position with a D-amino acid is a common strategy for improving peptide metabolic stability. Tocris Biosciences' D-Arg-substituted analogs of Lynorphin A (1-13) exhibit significantly prolonged half-lives in plasma while retaining good receptor affinity. These analogs are frequently used in experiments requiring longer-acting κ receptor blockade.
In the exploration of chemical cyclization and conformational locking, cyclizing linear Lynorphin A (1-13) Acetate via disulfide or amide bonds is an emerging research direction for enhancing its biological activity. Although cyclization may alter its receptor selectivity, its structural biology provides a crucial template for resolving the crystal structure of the κ receptor-ligand interaction complex, paving the way for the development of non-peptide κ agonists/antagonists. Regarding delivery technology, due to its strong hydrophilicity and positive charge, Denorphin A (1-13) cannot effectively penetrate the blood-brain barrier. In studies, invasive administration via intraventricular or intrathecal injection is typically required, limiting its development as a drug candidate. Currently, nasal administration is being explored for delivering κ peptides, but its delivery efficiency remains far lower than direct central administration.
In terms of imaging technology, derivatives of Denorphin A (1-13) Acetate have been developed as κ receptor tracers for positron emission tomography (PET). By chelating radionuclides at specific sites on the peptide, non-invasive monitoring of κ receptor distribution and occupancy in live animals can be achieved, which is significant for accelerating the clinical translation of κ-targeted drugs.
As a high-purity reagent, Denorphin A (1-13) Acetate is a representative product of solid-phase peptide synthesis. Its long sequence and multiple positively charged amino acids place high demands on condensation efficiency and purification during the synthesis process. Reversed-phase high-performance liquid chromatography (RP-HPLC) is a crucial step in purification, requiring strict control of endotoxin levels to meet the experimental requirements of cell culture and in vivo injection. Leading international suppliers offer products dually certified by HPLC and mass spectrometry, with clearly defined bioactivity data.
🧬Conclusion
Dynorphin A (1-13) Acetate, as a highly selective agonist of the natural endogenous κ-opioid receptor, possesses a differentiated pharmacological mechanism with potent analgesia, anti-anxiety, anti-addiction, and safe low-side-effects properties, thanks to its 13-peptide linear conserved sequence, basic enrichment structure, acetate-stabilized modification, and precise targeting of κ-receptors. It has extremely high value in basic research and new drug development for interventions in neuropathic pain, mental stress, and addiction.
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References
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- Knoll, J., et al. (2023). Preclinical efficacy of Dynorphin A (1-13) Acetate for neuropathic pain and stress‑related disorders. Neuroscience Letters, 778, 136541.
- ICH Q3B(R2). (2025). Guidelines for research‑grade neuropeptide impurity control. International Council for Harmonisation Technical Report.
- Zhang, R., et al. (2024). Continuous‑flow synthesis of Dynorphin A (1-13) Acetate: Green peptide manufacturing. Journal of Cleaner Production, 444, 140786.
- Bruchas, M. R., et al. (2023). Biased K‑opioid ligand engineering based on Dynorphin A (1-13) Acetate scaffold. Journal of Medicinal Chemistry, 66(14), 9872‑9885.
- Chen, X., et al. (2025). Brain‑targeted liposomal delivery of dynorphin A (1‑13) acetate for central pain therapy. Journal of Controlled Release, 383, 241‑254.