For centuries, medicinal leeches, particularly the species Hirudo medicinalis, have been used in traditional medicine to treat a variety of ailments. Modern scientific research has shed light on the complex composition of leech saliva and its remarkable healing properties, offering new possibilities for the treatment of various diseases.
The saliva of medicinal leeches contains a wide array of active compounds, including:
- Anticoagulants: Hirudin, antistatin, and plasma transglutaminase inhibitors I and II, which stabilize fibrin and prevent blood clotting.
- Platelet aggregation inhibitors: Apyrase, saratin, kalin, and destabilase, which have antibacterial properties, break down stable fibrin in blood clots, and stimulate nerve cell growth.
- Fibrinolytic agents: Hementin and hementerine.
- Platelet aggregation inhibitors and blood pressure regulators: PC-LS.
- Enzymes: Triglyceridase and cholesterol esterase, which break down triglycerides and cholesterol.
- Anti-inflammatory proteinase inhibitors: Bdelins, eglins, and hirustatin.
- Neurotransmitters: Dopamine, serotonin, histamine, and acetylcholine.
- Endorphins, which act as natural painkillers.
- Antimicrobial factors: Chloromycetin, hyaluronidase, and collagenase.
- Steroids: Cortisol, dehydroepiandrosterone, progesterone, testosterone, and estradiol.
- Antielastase, which breaks down elastin.
Structure of hirudin (ball-stick model) in complex with thrombin (ribbon model).
Photo taken from Wikipedia
The combined action of these compounds has a profound effect on various body systems:
Cardiovascular system: The anticoagulant, anti-aggregation, and fibrinolytic properties of leech saliva make it an effective treatment for thrombotic diseases, atherosclerosis, hypertension, and post-surgical care, particularly after replantation surgeries. Hirudin, a potent thrombin inhibitor, is considered more effective than aspirin or heparin in preventing heart attacks and strokes. Recombinant hirudin derivatives, such as desirudin and lepirudin, are registered in Germany for the treatment of thrombotic disorders.
Nervous system: Leech saliva contains endorphins, known as “happiness hormones,” which have a calming and euphoric effect and act as natural painkillers. Additionally, the saliva contains neurotransmitters essential for proper nervous system function. Compounds isolated from leech saliva, such as destabilase, bdellastatin, bdelin B, and eglin C, have been found to stimulate the growth of nerve cells, offering hope for the treatment of neurodegenerative disorders, neuromuscular dystrophy, Parkinson’s disease, and Alzheimer’s disease.
Inflammatory processes and pain management: Leech saliva contains numerous anti-inflammatory substances, such as eglin, a potent inhibitor of inflammatory factors released by human granulocytes. Bdelins, which accelerate wound healing, also have anti-inflammatory properties. Hirudotherapy has been found to reduce the intensity of pain in osteoarthritis and improve motor activity. It is used to treat various inflammatory conditions, including spine diseases, neuritis, rheumatoid arthritis, osteoarthritis, headaches, and sciatica.
Genitourinary system: Hirudotherapy has been used to treat various female diseases, such as vaginal inflammations, endometritis, adnexitis, ovarian or fallopian tube abscesses, ovarian cysts, and cervical erosions. In men, leeches are used to reduce prostate enlargement. The anti-inflammatory effects of leech saliva on the genitourinary system may be attributed to the presence of bdellastatin and acrosin inhibitors.
Infections: Medicinal leeches live in symbiosis with a microorganism that produces the antibacterial substance chloromycetin (chloramphenicol). As a result, leech therapy may be helpful in situations where chloramphenicol is indicated, such as meningitis, tetanus, Staphylococcus aureus infections, and meningococcal sepsis. Hyaluronidase, another substance produced by leeches, dissolves the sugar components of the cell walls of many microorganism spores. Destabilase has also been shown to have antibacterial properties.
Oncology: Studies have indicated the antitumor effects of extracts from the salivary glands of the Amazonian leech Haementeria ghilianii. When mice were inoculated with T 241 sarcoma and then intravenously administered an extract from the salivary glands of Haementeria ghilianii, tumor growth was inhibited. The specific substances responsible for this effect have not yet been identified, but the role of gilantins present in leech saliva has been suggested.
Dermatology and cosmetology: In the 19th century, women used leeches to achieve a more youthful appearance. Today, hirudotherapy is used to treat cellulite, acne, psoriasis, eczema, scleroderma, hyperpigmentation, rosacea, and telangiectasia, as well as to promote the healing of boils and abscesses. Antielastase, a substance released from leech saliva, slows down the breakdown of skin elastin and the aging process. Clinical studies have also shown that leech therapy is effective as an adjunctive treatment for lupus.
In conclusion, the complex composition of medicinal leech saliva, with its wide range of active compounds, offers a promising avenue for the treatment of various diseases. As modern research continues to unravel the secrets of this ancient therapy, hirudotherapy may find new applications in the fields of cardiology, neurology, dermatology, and oncology, among others.
