Context: Earthworm Eisenia foetida (Lumbricus rubellus), a traditional Chinese medicine, is used for treating many diseases, and its coelomic fluid has extensive biological functions.
Objective: The hemolytic, antibacterial and antitumor activities of an earthworm protein purified from coelomic fluid were investigated in vitro.
Materials and methods: We used ultrafiltration, gel chromatography, and ion exchange chromatography in sequence to isolate and purify an earthworm protein from coelomic fluid (ECFP), and ECFP was characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Hemolytic assay and antibacterial tests were applied to determine the cytolytic activity of ECFP. The MTT method was carried out to evaluate the antitumor effect of ECFP on HeLa cells and LTEP-A2 cells.
Results: ECFP, with molecular weight determined to be approximately 38.6 kilodaltons (KDa), was shown to possess significant hemolytic activity to chicken red blood cells (CRBC) (minimal hemolytic concentration 0.39 µg/mL). Antibacterial effect of ECFP obviously tested against Escherichia coli (minimal bactericidal concentration, MBC 180 µg/ mL) and Staphylococcus aureus (MBC 90 µg/mL) were observed. Moreover, ECFP notably inhibited the proliferation of HeLa cells (IC₅₀ 77 µg/mL) and LTEP-A2 cells (IC₅₀ 126 µg/mL) both in a time- and dose-dependent manner.
Discussion and conclusion: ECFP could serve as a component of the innate defense system of earthworms against foreign organisms, and thus it has potential pharmaceutical application in the future.