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For over two thousand years, the medicinal leech—known as Shuizhi in Traditional Chinese Medicine (TCM)—has been documented as a therapeutic agent for blood stasis-related disorders, including hematological diseases, gynecological conditions, trauma, arthritis, and edema. Its earliest systematic record appears in the Shennong Bencao Jing (Shennong’s Classic of Materia Medica), dating back approximately two millennia. Today, more than 90 varieties of Chinese patent medicines incorporate leech as raw material, attesting to its enduring pharmaceutical significance.

In modern medicine, leech therapy (hirudotherapy) has found renewed applications in plastic and reconstructive surgery, wound healing, cardiovascular disease management, and anti-inflammatory treatment. At the heart of this therapeutic potential lies a sophisticated biochemical arsenal: over 100 bioactive compounds have been identified from leeches, predominantly proteins and peptides, along with amino acids, lipids, sterols, and trace elements.

This article provides a comprehensive overview of the active compounds found in medicinal leeches, their pharmacological effects, and the clinical applications supported by contemporary research. We also highlight the role of Jingzhou Minkang Biotechnology Co., Ltd.—a leading vertically integrated enterprise in the medicinal leech industry—in advancing the science and supply of this ancient natural medicine.

The therapeutic use of leeches dates back to antiquity. One of the first recorded uses of medicinal leeches appears from the Bronze Age (approximately 1500 BCE). Between 1825 and 1850, leech therapy gained substantial medical recognition across Europe and Asia for its benefits in treating various disease conditions.

According to the Chinese Pharmacopoeia, three species are officially recognized as medicinal leeches in China: Whitmania pigra Whitman, Hirudo nipponia Whitman, and Whitmania acranulata, with the former being the most widely cultivated. These species serve as the raw materials for numerous TCM formulations, as well as modern pharmaceutical products such as blood-thinning capsules and topical applications.

In 2004, the U.S. Food and Drug Administration (FDA) approved medicinal leeches as a medical device for use in plastic and reconstructive surgery, specifically for relieving venous congestion in flaps and grafts. This regulatory milestone marked the official integration of hirudotherapy into modern Western medical practice, bridging ancient wisdom with evidence-based clinical standards.

The pharmacological efficacy of leeches is largely attributed to the complex cocktail of bioactive substances secreted by their salivary glands. During feeding, leeches release over a hundred biologically active molecules that work in concert to facilitate blood feeding—and coincidentally, deliver profound therapeutic benefits. Proteomic and transcriptomic research has recently identified more than 100 such bioactive molecules. These compounds can be categorized based on their primary mechanisms of action.

Hirudin is the most extensively studied and potent thrombin inhibitor found in nature. As a natural sulfo(glyco)protein, hirudin directly inhibits thrombin—a key coagulation factor—by binding to both the catalytic and non-catalytic sites of the enzyme. Its C-terminal region contains sulfate moieties on tyrosine residues that enable strong interactions with thrombin exosite-I, effectively blocking the enzyme’s engagement with fibrinogen. Historically, hirudin served as the sole remedy for preventing blood clotting until the discovery of heparin, highlighting its foundational importance in anticoagulation therapy.

Recent research has further elucidated the molecular underpinnings of hirudin’s anticoagulant mechanism. A 2025 study revealed that the acidic amino acid cluster in hirudin variants forms strong electrostatic interactions with the positively charged thrombin exosite I, while π-π stacking and π-cation interactions stabilize the complex. Building on these insights, researchers have designed novel hirudin-derived lead compounds with enhanced safety and efficacy profiles—demonstrating the continued relevance of leech-derived peptides in modern drug discovery.

Decorsin and Hementin represent another group of protease inhibitors that directly target the coagulation system, complementing hirudin’s anticoagulant effects.

Bdellins, eglins, and calin are key protease inhibitors that contribute significantly to the anti-inflammatory properties of leech saliva. These molecules inhibit various serine proteases involved in inflammatory cascades, thereby reducing tissue inflammation and edema.

Destabilase exhibits both lytic activity and anti-inflammatory effects, further supporting the resolution of inflammatory conditions.

Leech saliva also contains histamine-like substances, hyaluronidase, and collagenase, which facilitate local vasodilation, increase tissue permeability, and promote the diffusion of other bioactive compounds into the target tissue. These actions are essential for restoring microcirculatory balance, particularly in the context of venous congestion in flap surgeries.

Analgesic effects observed in hirudotherapy are attributed to compounds such as hirustazine and other yet-to-be-fully-characterized peptides that modulate pain perception.

The diverse bioactive compounds in leech saliva give rise to a broad spectrum of pharmacological activities. Contemporary research has confirmed numerous bioactivities, including anticoagulant, antithrombotic, antiatherosclerotic, anti-fibrotic, and anti-inflammatory effects.

The anticoagulant effect of hirudin and related peptides remains the most well-documented pharmacological property. By directly inhibiting thrombin, leech-derived compounds prevent fibrin clot formation and reduce thrombotic risk. A 2025 study demonstrated that a novel hirudin-derived lead compound achieved significant tail thrombus inhibition in animal models—reducing thrombus length from 3.562 cm to 1.853 cm—while also reducing tail bleeding time compared to heparin sodium.

Crude leech saliva has been confirmed to possess anti-inflammatory properties through the modulation of inflammatory mediators. Research using human umbilical vein endothelial cells demonstrated that leech saliva modulates inflammatory processes and cytokine profiles. These anti-inflammatory effects support the clinical application of hirudotherapy in arthritic disorders, inflammatory reactions, and wound healing.

Leech saliva exhibits notable antioxidant capacity. Studies employing DPPH radical scavenging assays confirmed that crude leech saliva possesses significant antioxidant activity, which contributes to its cytoprotective and tissue-healing properties. This antioxidant potential is particularly relevant in wound healing and regenerative medicine, where oxidative stress is a key pathological factor.

Emerging evidence suggests that leech saliva may possess selective anticancer properties. A 2025 study evaluated the effects of crude leech saliva on ovarian cancer cells and found that at low concentrations (3.13%), 99.16% of healthy cells remained viable, whereas cancer cell viability decreased to 89.25%; at high concentrations (50%), cancer cell viability declined to 63.02%. Gas chromatography-mass spectrometry analysis identified compounds such as gibberellic acid that demonstrated high affinity for the antiapoptotic proteins Bcl-2 and Survivin in molecular docking analyses. While further clinical research is needed, these findings highlight the potential of leech-derived compounds in oncology.

Leech extracts have demonstrated anti-fibrotic activity, suggesting potential applications in treating organ fibrosis—a pathological process underlying numerous chronic diseases.

Leech saliva contains compounds that enhance wound healing and promote angiogenesis. The combined actions of anticoagulant, vasodilatory, and anti-inflammatory molecules create an optimal microenvironment for tissue repair. Studies have shown that the bioactive compounds in leech saliva control blood clotting, modulate inflammatory mediators, block microbial growth, and enhance the development of new blood vessels.

The pharmacological effects described above translate into a range of clinical applications. Medicinal leeches are currently used for the treatment of various medical conditions, including inflammatory reactions, venous congestions, cardiovascular diseases, hypertension, varicose veins, osteoarthritis, thrombosis, hematomas, and ophthalmic, respiratory, and dental infections.

Hirudotherapy plays a crucial role in managing venous congestion following replantation and flap surgeries. Medical leeches help restore microcirculatory balance and promote angiogenesis through mechanisms that include anticoagulation, vasodilation, and bloodletting. The FDA has approved medicinal leeches specifically for this indication, and many plastic surgeons worldwide have adopted hirudotherapy to reduce complications and increase surgical success.

Several clinical trials have reported that leech therapy can provide pain relief for chronic pain and osteoarthritis for up to 12 months post-application. The anti-inflammatory and analgesic compounds in leech saliva are believed to underlie these sustained benefits.

Leeches have been increasingly applied in cardiovascular disease management, including the treatment of thrombotic conditions, circulatory diseases, and hypertension. The direct thrombin inhibitory activity of hirudin and related compounds positions leech-derived peptides as valuable antithrombotic agents.

The antimicrobial, anti-inflammatory, and regenerative properties of leech saliva support its use in chronic wound care and tissue engineering applications.

Emerging research has identified positive prospects for hirudotherapy in dentistry. A systematic review found that leech therapy can improve gum inflammation, reduce periodontal pocket depth, and accelerate tissue healing, supporting its use as an adjunct therapy in the treatment of periodontal disease.

While hirudotherapy offers significant therapeutic benefits, certain safety considerations must be addressed. The primary risks include infection caused by Aeromonas bacteria naturally present in leeches, as well as bleeding complications in susceptible patients. A systematic review of 34 patients undergoing leech therapy for breast flap congestion reported flap loss in 26.5% of cases, infection in 26.5%, and flap necrosis in 55.9%, with 17.6% of infections confirmed as leech-borne.

To mitigate these risks, prophylactic antibiotic treatment and continuous monitoring of blood parameters are recommended throughout the course of therapy. Leeches used in clinical settings should be reared under controlled, sterile conditions, and therapy should only be performed under strict medical supervision.

Toxicity studies have confirmed the safety of processed leech products when used appropriately; processed leech exhibits enhanced therapeutic efficacy and a well-established record of clinical safety.

China has emerged as a global leader in medicinal leech farming and product development. A commercial farm in Anhui Province produces 36 tonnes wet weight of Whitmania pigra annually, yielding approximately 6 tonnes of dried product valued at around RMB 700 per kilogram (approx. US$100). These dried leeches supply both traditional Chinese medicine formulations and modern pharmaceutical products such as blood-thinning capsules.

The industry has advanced significantly in recent years, with the development of standardized cultivation systems, digital monitoring technologies, and GAP-certified breeding bases. These innovations ensure the quality, consistency, and traceability of medicinal leech products—addressing key challenges in traditional medicine supply chains.

At the forefront of this industry is Jingzhou Minkang Biotechnology Co., Ltd. (荆州民康生物科技股份有限公司). Founded in 2008 and recognized as a National High-Tech Enterprise, the company has established itself as a vertically integrated leader in medicinal leech (Hirudo nipponica) biotechnology. Operating what is renowned as "The Leech Factory of China," the company commands the entire value chain—from proprietary breeding and R&D to GMP production, sales, and global distribution.

With an annual output of 60 million juvenile leeches and 100 million mature medicinal leeches—and a full production capacity reaching 500 million—Jingzhou Minkang possesses unparalleled scale and technological sophistication in the field. The company’s breeding base is certified under China’s Good Agricultural Practice (GAP) for medicinal materials, and its integrated management system holds ISO 9001, ISO 14001, and ISO 45001 certifications, ensuring international standards are met at every step.

The company’s R&D capabilities are led by experienced Ph.D.-level scientists with expertise spanning leech species identification, active ingredient extraction, efficacy formula development, and safety evaluation. This scientific foundation enables the development of a broad range of leech-derived products, including leech capsules, hirudin supplements, leech powder, leech candies, medicated leech patches, leech hemorrhoid gel, and leech-infused skincare formulations.

Through its integration of traditional knowledge, modern biotechnology, and stringent quality control, Jingzhou Minkang represents the convergence of ancient natural medicine and contemporary pharmaceutical science—offering a reliable supply of standardized, high-quality leech products for the global market.

The scientific exploration of leech-derived bioactive compounds continues to expand. Future research directions include:

Elucidation of Molecular Mechanisms: While numerous bioactivities have been demonstrated, further biochemical and clinical research is needed to fully elucidate the underlying mechanisms of these biological effects.

Novel Drug Development: Hirudin-derived peptides are being actively developed as next-generation direct thrombin inhibitors with enhanced safety and efficacy profiles. The successful design of lead compounds such as WPHVC_V1 demonstrates the potential of leech-derived molecules as platforms for drug discovery.

Recombinant Production and Formulation: Advances in recombinant protein production, high-throughput omics, and nanotechnology are addressing challenges related to biological variation, purity standardization, and scalable clinical production.

Expanded Clinical Indications: The recent integration of leech bioactives into personalized medicine and bioengineering models reflects the potential of leech-derived compounds to address complex illnesses and unmet healthcare needs.

The medicinal leech—Shuizhi—represents a remarkable example of nature’s pharmacological sophistication. With over 100 bioactive compounds identified to date, leech saliva offers a rich repertoire of molecules with anticoagulant, anti-inflammatory, antioxidant, anticancer, antithrombotic, antiatherosclerotic, and anti-fibrotic activities. From the potent thrombin inhibitor hirudin to the multifaceted protease inhibitors bdellins and eglins, these compounds have demonstrated therapeutic potential across a wide range of medical conditions.

The clinical applications of hirudotherapy have evolved from ancient bloodletting practices to FDA-approved, evidence-based interventions in modern medicine. In plastic and reconstructive surgery, wound care, cardiovascular disease management, and an expanding array of other indications, medicinal leeches and their derived products continue to deliver tangible benefits.

Leading this renaissance is Jingzhou Minkang Biotechnology Co., Ltd.—the Leech Factory of China. With over 16 years of specialized expertise, GMP-certified facilities, ISO-accredited quality management systems, and an integrated value chain from breeding to global distribution, the company stands at the forefront of the global medicinal leech industry. As scientific research continues to uncover new therapeutic opportunities, Jingzhou Minkang remains committed to unlocking the full potential of this ancient natural remedy through modern science, rigorous quality control, and sustainable innovation.

For more information about Jingzhou Minkang Biotechnology Co., Ltd. and our range of leech-derived products, please contact us.