RESUMEN
Since a few thousand years ago, the earthworm has been used as a drug for various diseases in China and the Far East. However, modern scientific pharmacological studies have not so far been performed. We extracted a very strong fibrinolytic enzyme from the earthworm, Lumbricus rubellus. This enzyme was heat-stable and displayed a very broad optimal pH range. Purification of the enzyme was performed and three partially purified fractions were obtained. These three fractions were further subdivided, and six purified fractions (F-I-0, 1, 2, F-II, and F-III-1,2) were finally obtained. Based on results of their enzymatic activities against various substrates, the fraction I enzymes are thought to represent chymotrypsin-like enzymes and the fraction III enzymes to represent trypsin-like enzymes. The fraction II enzyme appears to be neither a trypsin-nor chymotrypsin-like enzyme nor an elastase. We therefore designed trials for in vivo experiments on human volunteers. 120 mg of lyophilized earthworm powder was administered orally to 7 healthy volunteers (aged 28-52 years old) three times after meals every day for 17 days. Blood was withdrawn once a day before and at 1, 2, 3, 8, 11 and 17 days after commencing the administration. The fibrin degradation products (FDP) value, tissue plasminogen activator (t-PA) antigen level and t-PA activities were measured in the blood. Before the administration, the t-PA antigen level was 5.6 +/- 0.38 ng/ml, and it gradually increased until the 17th day. The FDP level was increased on the 1st and 2nd day after the administration, but had decreased and normalized by the 17th day. The fibrinolytic activities also tended to show an increase during the experiment. These results suggest that earthworm powder represents a possible oral thrombolytic agent. The earthworm enzyme may thus be applicable for treating patients with thalassemia.