Hirudin, contained in the salivary glands of fresh leeches, is a polypeptide composed of various amino acids, including aspartic acid 10, glutamic acid 13, cysteine 6, serine 4, glycine 9, threonine 4, alanine 1, valine 3, leucine 4, isoleucine 2, proline 3, phenylalanine 2, kojic acid 2, histidine 1, and lysine 4 (the number represents the number of molecules), because of the high content of amino acids with dihydroxyl groups in the molecule. Because of the high content of amino acids with dihydroxyl group in the molecule, its isoelectric point is ph3.8, and it is more stable to the denaturation reaction; the pure product is gray or white scales or powder, acidic, soluble in water, physiological saline and pyridine, insoluble in alcohol, acetone and benzene, and it is easy to be degraded when it meets with heat or in dilute acid. Hirudin has been destroyed in the dried herbs. Also contains heparin (heparin), anti-thrombin (antithromfin).

Pharmacology

1. Action on blood

Hirudin can prevent the action of thrombin on fibrin, hindering blood coagulation. Hirudin is not damaged by heat or ethanol. Hirudin is not destroyed by heat or ethanol. Hirudin also secretes a histamine-like substance, which can dilate capillaries and increase bleeding. The effect of the alcoholic extract of hirudin on blood coagulation is stronger than that of gadfly, worm and peach kernel, and the effect of the alcoholic preparation of hirudin is stronger than that of the aqueous preparation. Hirudin 20mg can prevent the coagulation of 100g of human blood.

The aqueous extract of hirudin can inhibit ADP-induced platelet aggregation in rats, and also inhibit platelet aggregation in normal people, and has the effect of antithrombotic.

Experiments have shown that leech has strong fibrinolytic effect on fibrin in vitro, and its activity is significantly higher than that of Salvia divinorum and rhubarb; in vivo, it also has fibrinolytic activity, and it can shorten the rabbit euglobulin lysis time (ELT) significantly. Therefore, leech can activate the fibrinolytic system and dissolve thrombus. It has also been reported that hirudin has a significant inhibitory effect on experimental thrombosis, and has a dissolving effect on experimental venous thrombosis caused by thrombin.

Hirudin extract can reduce whole blood specific viscosity and plasma specific viscosity in rats. It can shorten the electrophoresis time of erythrocytes. Clinical studies have shown that leeches have improved the concentration, viscosity and aggregation of patients with ischemic cerebrovascular disease due to abnormal blood rheology.

2. Effects on cardiovascular system

It has been reported that hirudin can increase myocardial trophic blood flow to a certain extent, and it has a protective effect on tissue ischemia and hypoxia. Hirudin can counteract coronary artery spasm induced by pituitary retroleptin in rabbits, and has the therapeutic effect of inhibiting myocardial ischemia. Hirudin can significantly reduce aortic atherosclerotic plaques, so that the collagen fibers within the plaque proliferation, cholesterol crystals decreased. It suggests that leeches have potential application value for the prevention and treatment of atherosclerosis.

Leech has the effect of dilating capillaries, improving microcirculation, and increasing renal blood flow. Its effect of improving microcirculation is similar to that of heparin, only the effect time is short. Experiments have shown that leeches have the effect of dilating peripheral blood vessels, increasing blood flow and decreasing vascular resistance, which is similar to the effect of popaverine hydrochloride.

3. Effect on pregnancy

Experiments have shown that leeches have the effect of terminating pregnancy in all periods of pregnancy in mice (including implantation and the early, middle and late stages of pregnancy). Different routes of administration have good effect on termination of early pregnancy. If exogenous progesterone and leeches are injected at the same time, premature labor can be prevented. Leeches have an inhibitory effect on ecchymotic lesions.

4, other effects

Leech has a significant reduction in cholesterol and triglycerides in experimental hyperlipidemic rabbits.

Hirudin has an inhibitory effect on tumor cells, and has a certain inhibitory effect on the growth of liver cancer in mice. Due to the high anticoagulant effect of hirudin, it is beneficial for anti-cancer drugs and immune-active cells to infiltrate into cancer tissues to kill cancer cells.