A team of researchers at Lanzhou University has made a significant breakthrough in the field of pain management by synthesizing a novel cyclic hexapeptide that exhibits potent opioid agonism with strong antinociceptive activity, suggesting potential as a new class of analgesics. Their findings were published in the Journal of Medicinal Chemistry in January 2024.

The published paper, titled “Structure-Activity Relationships of a Novel Cyclic Hexapeptide That Exhibits Multifunctional Opioid Agonism and Produces Potent Antinociceptive Activity“, details the structure-activity relationships of the newly synthesized peptide. The lead authors Qinqin Zhang, Biao Xu, and Dan Chen, alongside their colleagues, have analyzed the chemical properties and biological activity of the peptide in vitro.

The Discovery of a Novel Pain Reliever

The cyclic peptide, referred to as c[d-Lys^2^(5,2,0,2,5,0)], has been investigated for its interaction with kappa and mu opioid receptors, two primary receptor systems involved in mediating the effects of opioids. These receptors are critical targets for providing pain relief, but their activation often comes with severe side effects, including addiction and tolerance.

During in vitro studies, the newly synthesized peptide exhibited high affinity and potency as an agonist at the opioid receptors. Its structure is distinct from existing opioid analgesics, which might lead to a lower potential for abuse and addiction. By tweaking the peptide’s structure, the researchers found an optimized balance between efficacy and safety, making it a strong candidate for a new analgesic drug.

A Step Forward in Pain Management

The efficacy of the developed peptide for pain management represents a step forward in addressing the critical need for safer and more effective analgesics. The Lanzhou University’s research team’s approach could potentially minimize the side effects associated with current opioid-based pain management strategies.

Qinqin Zhang and colleagues detailed how the peptide’s cyclic structure contributes to its stability and prevents rapid degradation, which is a common challenge with peptide-based drugs. The structure-activity relationship analysis revealed that certain modifications in the peptide’s sequence enhanced its ability to trigger a potent antinociceptive response with reduced adverse effects.

Implications for Opioid-Related Treatments

This discovery poses a hopeful future for patients suffering from chronic pain. By providing a potential new drug that can more safely target the body’s pain-relief pathways, the strain on patients and the healthcare system caused by opioid addiction and overdose might significantly decrease.

Advancements in Medicinal Chemistry

The Journal of Medicinal Chemistry publication underscores the critical role of medicinal chemistry in the discovery and optimization of novel therapeutic agents. The cyclic hexapeptide represents not just a possible new pain relief option but also showcases the power of structural chemistry in uncovering the nuances of how small changes at the molecular level can lead to significant differences in drug action and safety.

The work by the researchers at Lanzhou University demonstrates the importance of a rigorous, methodical approach to drug discovery, especially when dealing with compounds like opioids, which have a complex relationship between therapeutic benefits and potential for abuse.

Future Research and Development

While the results are promising, this novel peptide requires further research to evaluate its efficacy and safety in vivo. Clinical trials will be necessary to ascertain its potential as a therapeutic drug and to determine any long-term effects or possible interactions with other medications.

Researchers anticipate that additional derivatives of this peptide might be synthesized and evaluated, highlighting the possibility of a new class of drugs emerging from these findings. This could lead to a broadened understanding of how to design analgesics that provide effective pain relief with diminished risks of addiction and other side effects commonly seen with opioid treatments.


The discovery of the multifunctional opioid cyclic hexapeptide with potent antinociceptive activity offers a beacon of hope in the ongoing fight against chronic pain and the opioid crisis. With the concerted efforts of scientists from around the world, such as the team at Lanzhou University, novel therapeutic agents may soon emerge, transforming the landscape of pain management and improving the quality of life for millions of individuals suffering from chronic pain.


1. Zhang, Q., Xu, B., Chen, D., Wu, S., Hu, X., Zhang, X., … Fang, Q. (2024). Structure-Activity Relationships of a Novel Cyclic Hexapeptide That Exhibits Multifunctional Opioid Agonism and Produces Potent Antinociceptive Activity. Journal of Medicinal Chemistry, 67(1), 272-288. DOI: 10.1021/acs.jmedchem.3c01347.


1. Opioid Agonism
2. Antinociceptive Activity
3. Cyclic Hexapeptide
4. Structure-Activity Relationships
5. Analgesic Drug Discovery

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Last Update: January 22, 2024