Silk sericin as a moisturizer: an in vivo study

Abstract

Excessive transepidermal water loss (TEWL) is the one of the causes of dry skin, and skin moisturizers have been used to overcome it. The purpose of this research was to study the moisturizing effect of sericin, a silk protein. Because silk sericin has resemblance with the natural moisturizing factor (NMF), it has been studied for its application in skin cosmetics. Sericin gels were prepared using sericin solution and with pluronic and carbopol as stabilizers. The gels were applied on the skin of healthy human volunteers and its moisturizing efficiency was evaluated by measuring the skin hydroxyproline content, impedance, TEWL, and scanning electron microscopy (SEM) results. Decrease in skin impedance, increase in hydroxyproline level, and hydration of epidermal cells revealed the moisturizing effect of sericin, whereas decrease in the value of TEWL may be attributed to occlusive effect, which prevents water loss from the upper layer of the skin. Skin surface topography revealed the smoothness of the upper layer of the skin as a result of moisturization. Increase in the intrinsic moisturization of skin by sericin may be attributed to restoration of the amino acids and its occlusive effect. Thus, it would become a promising and important moisturizing ingredient in moisturizing formulations.