High molecular weight sericin/glycerol composition as a novel skin care material supporting human skin barrier function

Abstract

Silk sericin, derived from the domesticated silkworm Bombyx mori, exhibits a highly hydrophilic nature due to its rich content of hydrophilic amino acids. This property, along with its excellent film-forming ability in its native high-molecular-weight state, suggests its potential use as an additional skin barrier. High-molecular-weight sericin (HS) can be efficiently sourced from the Sericin Hope strain, which produces cocoons composed exclusively of sericin. This study investigates the potential of HS as a skin protector. For safety, calcium chloride (CaCl₂), a neutral salt, was used to dissolve the Sericin Hope cocoon shells to extract HS. The extracted sericin was then stabilized with glycerol in fluid formulations. A centrifugation method was employed to desalt excess CaCl₂, offering a simpler and faster alternative to conventional dialysis. When a moisturizing cream containing the desalted high-molecular-weight sericin/glycerol composition (HSG) was applied to human skin, it significantly suppressed transepidermal water loss (TEWL) compared to a placebo cream without HSG. This suppression of TEWL underscores HSG’s ability to prevent water transpiration from human skin. The study concludes that HSG could serve as a useful skin protectant to support the skin barrier.