Protein substance (also called sericin) formed by converting silk, which is the soft, lustrous thread obtained from the cocoon of the silkworm. Silk protein can have water-binding properties for skin. However, whether the protein applied to skin is derived from animals or plants, the skin can’t tell the difference. There is a small amount of research showing silk protein may have topical antioxidant properties (Source: Bioscience, Biotechnology, and Biochemistry, January 1998, pages 145–147).