Cosmeceutical Critique

Sericin, a versatile silk protein, has multiple potential roles in dermatology


 

Inexpensively obtained as a silk industry by-product, sericin is a glycoprotein found to confer various biologic effects.1 The globular protein sericin has also long been known to exhibit antityrosinase and immunomodulatory activities.2,3 This column focuses on the wide range of emerging and potential applications of sericin in cutaneous treatments.

Protection against solar radiation and photoaging

Tasar Silkworm with cocoon Sailesh Patnaik/CCA-SA 4.0 International

Studies in mice to evaluate the potential antioxidant and skin-protective effects of sericin by Zhaorigetu et al. in 2003 revealed that, by diminishing oxidative stress, cyclooxygenase-2 protein, and cell proliferation, sericin exerted a photoprotective effect against acute harm and tumor promotion elicited by UVB.4

Using mouse skin models, Dash et al. showed in 2008 that the silk protein sericin derived from the tropical tasar silkworm is a robust antioxidant and photoprotective agent, displaying a capacity to block UVB-induced apoptosis in irradiated (30 mJ/cm2 UVB) human keratinocytes and, as compared with the mulberry silkworm, yielding protection against oxidative stress.5,6

In 2015, Berardesca et al. conducted a randomized, double-blind, vehicle-controlled, split-face study over 8 weeks in 40 women (ages 40-70 years) to assess the antiaging effects of topically applied combination therapy including gold silk sericin, niacinamide, and signaline. The investigators observed significant improvements in stratum corneum hydration, barrier function, skin elasticity, and roughness as compared with skin treated with the control formulation. They concluded that this combination formulation featuring gold silk sericin warrants attention in the arsenal for ameliorating signs of aging female facial skin.7

A year earlier, Aramwit and Bang introduced a bacterial nanocellulose gel shown to effectively release silk sericin for facial treatment. Formulated at a pH of 4.5, the bioactive mask exhibited an ultrafine and pure fiber network structure. The authors noted that the gel was less adhesive than the commercially available paper mask, while the silk sericin product displayed greater moisture absorption capacity. In vitro cytotoxicity assessments also revealed that the product is safe for facial treatments.8

Cosmeceutical antioxidant for hyperpigmentation

In 2019, Kumar et al. demonstrated the inhibitory effect of topically applied silk sericin derived from Antheraea assamensis against UV-induced melanogenesis in mouse melanoma. They suggested that the formulation shows promise as a cosmeceutical antioxidant agent designed to address hyperpigmentation.3

The previous year, Aramwit et al. demonstrated using an in vitro model that urea-extracted sericin displays a capacity to inhibit melanogenesis by hindering tyrosinase activity, attenuating inflammation and allergic reactions, and reducing the expression of microphthalmia-associated transcription factor, a marker of melanogenesis regulation, in melanocytes and keratinocytes.2

Potential use as an adjunct psoriasis treatment

A combination of naringin (from Citrus maxima) and sericin (from Bombyx mori) was evaluated in 2019 by Deenonpoe et al. for the treatment of psoriasis. They isolated human peripheral blood mononuclear cells from 10 healthy subjects and 10 patients with psoriasis. The combination formulation was much more effective than either compound alone in significantly reducing mRNA expression and the synthesis of proinflammatory cytokines in samples from psoriasis patients. The investigators concluded that the down-regulation of proinflammatory cytokines imparted by the naringin/sericin product points toward its possible clinical use as a complementary treatment for psoriasis and other inflammation-mediated conditions.9

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