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In traditional Chinese medicine, the medicinal leech—known as shuizhi (水蛭)—has been used for over two millennia to treat conditions ranging from blood stasis to cardiovascular disease. But for centuries, its therapeutic mechanisms remained a mystery, explained largely through the framework of humoral theory and empirical observation. Today, a growing body of experimental research is finally catching up with what traditional practitioners long believed: leeches possess powerful anti-inflammatory properties, and modern science is beginning to understand exactly how they work.

What the Research Shows

Several recent studies have provided compelling evidence for the anti-inflammatory effects of leech-derived compounds. One of the most notable involves a polysaccharide called SZ, isolated from Hirudo nipponica Whitman, the very species we cultivate at Jingzhou Minkang Biotechnology. Researchers extracted SZ through enzymatic hydrolysis, alkaline extraction, and chromatographic purification, then characterized its structure using high-performance liquid chromatography and nuclear magnetic resonance spectroscopy. What they found was a complex polysaccharide with a molecular weight of 221.28 kDa, predominantly composed of glucose, that exhibited potent immune-enhancing activity in laboratory tests.

When tested on RAW264.7 macrophages—immune cells that play a central role in the body‘s inflammatory response—SZ significantly modulated the expression of key inflammatory cytokines, upregulating iNOS, TNF-α, and IL-6 mRNA expression. These findings, published in the International Journal of Biological Macromolecules, suggest that SZ has the potential to serve as an immunomodulatory agent, offering a natural avenue for managing inflammation.

This isn’t an isolated finding. Another study, published in Immunologic Research, analyzed lyophilized leech saliva extract using LC-MS/MS and proteomics. The results were striking: the extract decreased the production of pro-inflammatory cytokines by activated mammalian macrophages compared to control groups. The authors concluded that lyophilized leech saliva could be utilized as an anti-inflammatory biotechnological drug candidate against inflammatory and autoimmune disorders.

Meanwhile, transcriptomic analysis of Hirudo nipponia has revealed a rich repertoire of active ingredients in the leech‘s saliva, including anticoagulant factors such as hirudin, as well as previously unrecognized immune-related genes. The study, published in Developmental & Comparative Immunology, confirmed that the species possesses significant medical potential due to its anticoagulant, anti-inflammatory, and antibacterial effects.

From the Lab Bench to Real Patients

But what does all this mean outside the laboratory? Clinical evidence is accumulating as well. In a study on patients with rheumatoid arthritis, researchers observed reductions in inflammatory markers alongside measurable decreases in joint inflammation following leech therapy. A randomized trial on knee osteoarthritis found that a single treatment with four to six locally applied leeches provided symptomatic relief comparable to a 28-day course of topical diclofenac.

Perhaps most dramatically, a 2026 study published in the Chinese Journal of Traditional Medical Traumatology & Orthopedics examined the effects of hirudin on diabetic foot ulcer healing in rats. The results were unambiguous: the model group showed extensive inflammatory cell infiltration and sparse new blood vessels, while hirudin-treated groups showed significantly fewer inflammatory cells and increased angiogenesis. The study also measured reductions in serum levels of TNF-α, IL-6, and IL-8—all key drivers of inflammation.

Why This Matters

The implications are significant. Chronic inflammation underlies a staggering range of modern diseases: arthritis, cardiovascular disease, diabetes complications, autoimmune disorders, and more. The search for effective anti-inflammatory agents that are both potent and well-tolerated is ongoing, and natural products offer a promising alternative to conventional pharmaceuticals, which often come with side effects such as gastrointestinal bleeding, kidney damage, or increased cardiovascular risk.

What makes leech-derived compounds particularly interesting is their multi-target mechanism of action. Unlike many synthetic drugs that block a single pathway, the active ingredients in leech saliva and body tissue appear to work through multiple signaling pathways simultaneously. The polysaccharide SZ, for instance, modulates inflammatory cytokine expression through immune cell activation. Hirudin has been shown to regulate the VEGF/Notch1 pathway to promote wound healing and reduce inflammation. And leech saliva extract works directly on activated macrophages to suppress pro-inflammatory cytokine production.

Look Ahead

At Jingzhou Minkang Biotechnology, we‘ve spent nearly two decades building the infrastructure to make this science practical. As the only large-scale, standardized, factory-based leech farming operation in China, we maintain the country’s largest Hirudo nipponia population across 200 acres of breeding facilities, producing over 100 tons of medicinal leeches annually. Our farming methods have earned GAP certification, and our proprietary cultivation techniques—developed entirely in-house—have filled multiple technical gaps in domestic leech aquaculture.

But farming is only half the story. We‘ve been investing heavily in R&D, expanding our product line from traditional Chinese medicinal slices to cosmetics and other applications, all backed by the kind of quality control that has earned us recognition through platforms like Xinhua Net‘s premium product selection.

The future of leech-derived therapeutics lies in standardization and innovation. Researchers are already working to identify the most active ingredients in leech saliva, with plans to test them on animal models of inflammatory and autoimmune disorders. Meanwhile, advances in recombinant production technology are opening the door to biotechnological drug candidates that could replicate the benefits of leech-derived compounds without the variability inherent in natural products.

For us at Jingzhou Minkang, the path forward is clear: continue refining our cultivation and processing methods, deepen our research into the anti-inflammatory mechanisms of Hirudo nipponia, and bridge the gap between ancient wisdom and modern medicine. The evidence is mounting. Now it‘s time to build on it.

If you’re interested in learning more about our research into leech-derived anti-inflammatory compounds, or exploring partnership opportunities in product development and clinical applications, please contact our team at Jingzhou Minkang Biotechnology.

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About Jingzhou Minkang Biotechnology Co., Ltd.
*Founded in 2008 and based in Gong‘an County, Hubei Province, Jingzhou Minkang Biotechnology is China’s leading producer of the medicinal leech Hirudo nipponia. With 200 acres of GAP-certified breeding facilities, proprietary cultivation technology, and an annual output exceeding 100 tons, the company is at the forefront of integrating traditional leech medicine with modern biotechnology.*