Silk protein can have water-binding properties for skin. However, whether the protein applied to skin is derived from animals or plants, your skin can’t tell the difference. There is a small amount of in vitro research showing silk protein may have topical antioxidant properties.
Not a vegan-friendly ingredient.
Silk protein as an antioxidant
“This report indicates that the silk proteinsericin from the non-mulberry tropical tasar silkworm, A. mylitta can serve as a valuable antioxidant.”
Silk protein as a treatment for pruritus (itchy skin)
“We conclude that sericin (silk protein) cream has a high potential for reducing UP (uremic pruritis) in hemodialysis patients.”
Bioscience, Biotechnology, and Biochemistry, January 1998, pages 145–147
Source: BMB Reports, 2008 Mar 31;41(3):236-41. Antioxidant potential of silk protein sericin against hydrogen peroxide-induced oxidative stress in skin fibroblasts.
Source: BMC Nephrology 2012 Sep 24;13:119. doi: 10.1186/1471-2369-13-119. Sericin cream reduces pruritus in hemodialysis patients: a randomized, double-blind, placebo-controlled experimental study.