Sericin helps in Skin Repair

How Does Sericin Help with Skin Repair?

Introduction

Sericin, a silk protein derived from the cocoon of the silkworm Bombyx mori, has garnered significant attention in the cosmetic and pharmaceutical industries for its remarkable skin repair properties. This blog delves into the scientific mechanisms through which sericin aids in skin repair, backed by research data and clinical studies.

The Science Behind Sericin

Sericin is a glycoprotein that forms a protective layer around the fibroin fibers in silk. It is rich in amino acids such as serine, glycine, and aspartic acid, which contribute to its excellent moisturizing and protective properties. The unique composition of sericin allows it to interact effectively with keratin in the skin, forming a protective film that enhances skin hydration and elasticity.

Mechanisms of Skin Repair

1. Collagen Production

Collagen is a vital protein that maintains the structural integrity of the skin. Sericin has been shown to stimulate collagen production, which is crucial for skin repair and regeneration. Increased collagen levels improve skin elasticity and reduce the appearance of wrinkles and fine lines.

1.1 Measurement of Collagen Production

Collagen production was measured using several biochemical markers and methods:

  • Hydroxyproline Content: Hydroxyproline, a major component of collagen, was quantified to assess collagen synthesis. This method involves hydrolyzing the tissue samples and measuring the hydroxyproline content using colorimetric assays[5].
  • Immunohistochemistry: Specific antibodies against collagen types I and III were used to stain tissue sections, allowing visualization and quantification of collagen deposition[5].
  • RT-qPCR: The expression levels of collagen-related genes (e.g., COL1A1, COL3A1) were analyzed using real-time quantitative PCR to determine the upregulation of collagen synthesis pathways[5].
1.2 Quantification of Collagen Stimulation

Studies have shown that sericin significantly increases collagen production in various models:

  • In vitro Studies: Sericin at concentrations higher than 200 μg/mL induced collagen production in fibroblasts, with a notable increase in hydroxyproline content. Specifically, collagen production increased by approximately 30-40% compared to the control group without sericin treatment[5].
  • In vivo Studies: Sericin-treated skin showed increased collagen deposition, fibrosis, and fibroblastic activity in animal models. For instance, a study on Wistar albino rats demonstrated significant collagen deposition in 83.33% of the sericin-treated group[5].
1.3 Supporting Studies
  • Aramwit et al. demonstrated that sericin significantly increased collagen production in human fibroblasts, with a notable increase in hydroxyproline content[5].
  • Tsubouchi et al. showed that sericin enhanced the proliferation and collagen synthesis in fibroblast cultures, indicating its potential in wound healing applications[5].

2. Antioxidant Properties

Sericin exhibits potent antioxidant properties, which help neutralize free radicals that cause oxidative stress and skin damage. By reducing oxidative stress, sericin minimizes cellular damage and promotes healthier skin.

2.1 Measurement of Antioxidant Activity

The antioxidant activity of sericin was measured using several assays:

  • Trolox Equivalent Antioxidant Capacity (TEAC) Assay: This assay measures the antioxidant capacity of sericin by comparing it to Trolox, a water-soluble vitamin E analog. The antioxidant capacity is expressed in Trolox equivalents[2].
  • DPPH and ABTS Assays: These assays measure the ability of sericin to scavenge free radicals, with results expressed as the percentage reduction in radical concentration[2].
  • Markers of Oxidative Stress: Levels of malondialdehyde (MDA), a marker of lipid peroxidation, and activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were measured in sericin-treated skin[5].
2.2 Quantification of Antioxidant Activity

Studies have shown significant reductions in oxidative stress markers in sericin-treated skin:

  • Reduction in MDA Levels: Sericin treatment resulted in up to a 50% reduction in MDA levels, indicating decreased lipid peroxidation and oxidative damage[5].
  • Increase in Antioxidant Enzyme Activity: Sericin-treated skin showed increased activities of SOD, CAT, and GPx, enhancing the skin’s antioxidant defense system[5].
2.3 Supporting Studies
  • A study by Aramwit et al. demonstrated that sericin significantly reduced oxidative stress markers in wound healing models, with a notable decrease in MDA levels and an increase in antioxidant enzyme activities[5].
  • Another study highlighted that sericin’s antioxidant activity is primarily due to its ability to chelate trace metals and scavenge reactive oxygen species (ROS)[5].

3. Hydration and Moisture Retention

One of the standout features of sericin is its ability to retain moisture. Sericin forms a protective barrier on the skin’s surface, preventing water loss and maintaining hydration. This property is particularly beneficial for dry and damaged skin, as it helps restore the natural moisture balance, leading to smoother and more supple skin. The high serine and threonine content in sericin contributes to its moisture-retaining capabilities.

3.1 Measurement of Skin Hydration and Moisture Retention

Several methods are used to assess the hydration and moisture retention properties of sericin:

  • Transepidermal Water Loss (TEWL): This is a primary marker for skin barrier function and hydration. Lower TEWL values indicate better moisture retention[1].
  • Impedance Measurements: Skin impedance decreases with increased hydration, providing a quantitative measure of moisture levels[1].
  • Hydroxyproline Levels: An increase in hydroxyproline in epidermal cells indicates improved hydration[1].
  • Corneometer Measurements: This device directly measures skin hydration levels, often reported in arbitrary units (AU)[1].
3.2 Quantification of Skin Hydration and Moisture Retention

Studies have shown significant improvements in skin hydration with sericin treatment:

  • In a study using NC/Nga mice, dietary sericin supplementation increased epidermal hydration from 27.2 ± 1.67 AU in the control group to 36.0 ± 2.41 AU, matching levels of normal skin (34.1 ± 2.32 AU)[1].
  • Clinical studies have reported that sericin creams can increase skin hydration by forming an occlusive layer, reducing TEWL responsible for skin dryness[1].
3.3 Supporting Studies
  1. Padamwar et al. conducted an in vivo study demonstrating sericin’s moisturizing effect on human skin. They observed decreased impedance and increased hydroxyproline levels, indicating improved epidermal hydration[1].
  2. Kim et al. found that dietary supplementation with 1% sericin for 10 weeks improved epidermal hydration in an animal model of atopic dermatitis. This improvement was attributed to increased levels of filaggrin and free amino acids, which are crucial for skin moisture retention[1].
  3. A clinical study by Aramwit et al. used an 8% sericin cream for treating uremic pruritus in patients with end-stage renal disease. The treatment resulted in greater skin hydration, less irritation, and reduced skin pigmentation[1].

4. UV Protection

Sericin has been shown to provide significant protection against UV-induced skin damage. This property is particularly valuable in skincare formulations aimed at preventing photoaging and reducing the risk of skin cancer.

4.1 Markers Used to Check UV Damage in Skin

Several markers are used to assess UV damage in skin:

  1. 4-Hydroxynonenal (4-HNE): A marker of lipid peroxidation and oxidative stress.
  2. Cyclooxygenase-2 (COX-2): An enzyme involved in inflammation and oxidative stress.
  3. Proliferating Cell Nuclear Antigen (PCNA): A marker of cell proliferation, which increases with UV damage.
  4. Malondialdehyde (MDA): Another marker of lipid peroxidation.
  5. Sunburn Cells: Apoptotic keratinocytes that appear after UV exposure.
  6. Thymine Dimers: DNA lesions specific to UV damage.
4.2 Quantification of Sericin’s UV Protection

Studies have demonstrated significant improvements in UV protection with sericin:

  1. Zhaorigetu et al. found that topical application of sericin (5 mg) reduced UVB-induced elevation of 4-HNE, COX-2, and PCNA in mouse skin. The reduction was approximately 50% for these markers compared to UVB-exposed skin without sericin treatment.
  2. In the same study, sericin reduced tumor incidence by about 65% in a long-term UVB exposure experiment.
  3. Zhaorigetu et al. also demonstrated that sericin reduced UVB-induced oxidative stress in hairless mouse skin, with a significant decrease in lipid peroxidation and an increase in glutathione levels.
4.3 Supporting Studies
  1. Zhaorigetu et al. (2003) demonstrated sericin’s photoprotective effect against UVB-induced acute damage and tumor promotion in mouse skin.
  2. Zhaorigetu et al. (2007) showed that sericin suppresses DMBA-TPA-induced mouse skin tumorigenesis by reducing oxidative stress, inflammatory responses, and endogenous tumor promoter TNF-alpha.
  3. Padamwar et al. (2005) reviewed the various properties of sericin, including its UV protection capabilities.

Applications in Skincare

Sericin’s unique properties make it an ideal ingredient for various skincare products, including moisturizers, serums, and wound healing creams. Its ability to enhance collagen production, provide antioxidant protection, retain moisture, and reduce UV damage makes it a versatile and valuable addition to cosmetic formulations.

Conclusion

Sericin is a powerful silk protein with multiple benefits for skin repair. Its ability to stimulate collagen production, provide antioxidant protection, retain moisture, and reduce inflammation makes it a valuable ingredient in skincare and wound healing products. Incorporating sericin into your skincare routine can lead to healthier, more resilient skin. Serione can provide high quality Raw Sericin for your Skin care brands. Check out our product page here to know more.

References

  1. Hydrolyzed silk in skincare, What is?
  2. Common Trends and Differences in Antioxidant Activity Analysis of Phenolic Compounds
  3. Spectrophotometric Assays for Total Antioxidant Capacity (TAC)
  4. Silk Sericin Protein Materials: Characteristics and Applications in Biomedical Fields
  5. Effects of Silk Sericin on Incision Wound Healing in a Dorsal Skin Model
  6. Trolox Equivalent Antioxidant Capacity (TEAC-ABTS) Assay Kit
  7. Inhibitory effects of silk protein, sericin on UVB-induced acute damage and tumor promotion by reducing oxidative stress in the skin of hairless mouse

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