Hepatic Lipids Deposition Were Alleviated by Fibrinolytic Enzyme:a Protein Extracted from Earthworms

The present study aimed to explore the lipid‐lowering effect of fibrinolytic enzyme from earthworms on high‐fat‐fed mice. Earthworms were rinsed and homogenized. Homogenates were extracted by ammonium sulfate precipitation to obtain crude protein and it was further purified by Sephadex G‐75 gel filtration chromatography and DEAE‐sepharose Fast Flow anion‐exchange chromatography. Fibrinolytic enzyme activity was determined by Nα‐Benzoyl‐L‐arginine ethyl ester (BAEE) method and its purity and molecular weight was determined by SDS‐PAGE. There were 2 elution peaks after Sephadex G‐75 gel chromatography and the one showed fibrinolytic enzyme activity was collected and further purified by anion‐exchange chromatography.4 elution peaks were then found and only one showed fibrinolytic enzyme activity and thus was collected and submitted to SDS‐PAGE.It was showed that only one band could be detected and the molecular weight was estimated to be 33kD. 160 Kunming mice (80 male and 80 female, wt 17–23g) were divided into 5 groups. Control group were fed on a basal diet for 6 weeks. High‐fat‐fed group were fed on a diet consisting of additional 1% cholesterol, 0.5% sodium deoxycholate and 10% lard on basal diet for 6 weeks. High dose fibrinolytic enzyme group were fed on high‐fat diet for 3 weeks and then treated with 0.2ml original purified fibrinolytic enzyme by gavage everyday for 3 weeks. Medium and low dose group followed the same feeding and treatment pattern as high dose group did except that diluted fibrinolytic enzyme was introduced to mice, 5× dilution and 10× dilution for medium dose group and low dose group respectively. It was found that heptic triglycerides(TG) were 2.42±0.07 mM, 2.08±0.12 mM, 1.86±0.11 mM, 3.39±0.15 mM in low dose group, medium dose group, high dose group and high‐fat‐fed group respectively. There was a significant difference between three fibrinolytic enzyme treated groups and high‐fat‐fed group(P<0.05).Hepatic total cholesterol(TC) were 3.97±0.09 mM, 2.89±0.29 mM, 2.75±0.34 mM, 5.89±0.48 mM in low dose group, medium dose group, high dose group and high‐fat‐fed group respectively. There was also a significant difference between three fibrinolytic enzyme treated groups and high‐fat‐fed group(P<0.05). Besides, compared with high‐fat‐fed group, three fibrinolytic enzyme treated groups all showed significant decreased level of malonaldehyde (MDA), aspartate aminotransferase(AST), alanine aminotransferase(ALT) and increased level of superoxide dismutase(SOD)(P<0.05). It was also shown in histotomy that fibrinolytic enzyme treated groups had lower level of inflammatory cell infiltration and alleviated hepatic steatosis compared with high‐fat‐fed group. The present study comfirmed a lipid‐lowering effect of fibrinolytic enzyme from earthworms on high‐fat‐fed mice. However its underlying mechanism needs to be determined. Support or Funding Information This study was financially supported by grant from National Natural Science Foundation of China (No. 31502135) and Hunan province science and technology plan(No.2012NK4030).