Abstract: Superoxide dismutase (SOD) has been demonstrated to be an important antioxidant, which protects the cells exposed to the toxicity of oxygen and has displayed huge application value and development prospect. The phosphate buffer was used to extract SOD, the antioxidant component of earthwarm (Eisenia foetida). Four key extraction process parameters factors selected for single-factor tests were phosphate buffer pH value，Heat-treatment temperature，Ratio of solid to liquid, and degree of saturation((NH₄)₂SO₄). Four factors and four levels of orthogonal experiment were used to determine the optimum factors levels above. Then activity of the SOD was measured by adjacent benzene three phenolic autoxidation method. Results indicated that the optimal levels of these parameters were as follows: phosphate buffer pH value 8.0, the heat treatment temperature 30⁰C, ratio of solid to liquid 6, and degree of saturation((NH₄)₂SO₄) 51%~70%. Under these conditions, the activity of the SOD was up to 2895.32U/g[FW]. This study provided a technical basis for the production of large scale production of SOD from earthworm.

Key words: earthworm, superoxide dismutase, activity, extraction conditions, orthogonal experiment