Antioxidant activity of chemically and enzymatically modified sericin extracted from cocoons of Bombyx mori

• The relationship between sericin protein and its antioxidant activity is proposed.
• The CSE treated with protease exhibit an excellent antioxidant activity.
• The treatments with DTT, β-ME and UV light decrease antioxidant activity.
• The antioxidant activity of SNT fraction is higher than the Yellow-PT fraction.

Thai silk cocoons from polyvoltine silkworm strain, Nangnoi, contain several antioxidant factors, pigments and protein. The present study investigated relationship between sericin protein treated with DTT, β-mercaptoehanol, UV light and protease enzyme and antioxidant activity of resultant sericin protein. The antioxidant activity of crude sericin extract (CSE) treated with protease enzyme measured by ABTS and DPPH assays showed 5.0-fold and 3.0-fold higher activity than that of untreated CSE, while DTT, β-mercaptoethanol and UV light treatments were found to significantly decrease antioxidant activity of CSE. Then, CSE was fractioned by salting out. The colorless supernatant (SNT) fraction showed the highest antioxidant activity. In addition, the antioxidant activity of fractionated sericin protein treated with various treatments showed similar results to those of similarly treated CSE. The results obtained in this study suggest that sericin protein modified using protease enzyme could be adopted as ingredients in food and cosmetic applications.

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