Introduction
The skin, as an organ constantly exposed to the external environment, performs the crucial role of protecting the human body from physical damage and chemical substances while preventing moisture loss. Particularly, the stratum corneum, the outermost layer of the epidermis, is essential for skin moisturization and protection. It is well-established that maintaining a moisture content of over 10% in the stratum corneum is vital for healthy skin
Moreover, lamellar structures play a significant role in skin moisturization and barrier functions. Lamellar structures are a type of emulsified membrane composed of phospholipids, which are arranged in successive layers of oil and water phases. The structural characteristics of lamellar structures provide not only moisturization but also excellent stability and usability (Proksch et al., 2008).
Scutellaria baicalensis, native to East Asia including Korea, is known for its efficacy in treating various inflammatory conditions. The major active components of Scutellaria baicalensis roots are glycosides such as baicalin and wogonoside, along with their aglycones baicalein and wogonin. Additionally, other components like chrysin and oroxylin A are present. These constituents are reported to exhibit strong antioxidant, anti-inflammatory, and antimicrobial activities within the human body (Zhao et al., 2016).
In this study, the objective is to evaluate the efficacy of a lamellar structured emulsion containing Scutellaria baicalensis root extract in improving skin surface moisture, reducing transepidermal water loss (TEWL), and alleviating itch through clinical trials (Rawlings et al., 2004).
Materials and Methods
1. Preparing Scutellaria baicalensis Extract Using Supercritical Extraction
Prepare 100 g of finely cut, dry goldenseal root and use a supercritical extractor (ARIinstrument) and supercritical extraction using supercritical carbon dioxide at 45℃ and 350 bar to obtain 0.62 g of golden extract. Meanwhile, the ethanol used as a co-solvent was removed using a reduced pressure evaporator.
2. Preparation of Lamellar Structured Emulsion Containing Scutellaria baicalensis Extract
The lamellar structure is a type of emulsified form composed of phospholipids, where oil and water layers alternately stack to form a block-like arrangement. The structural characteristics of this lamellar structure contribute to its properties. When a liquid crystal phase is formed, the viscosity of the emulsion particles increases, and the structure becomes more stable. Compared to conventional O/W or W/O structures, the lamellar structure acts as a barrier with higher moisturizing properties due to its unique characteristics.
The lamellar structure consists of multiple layers of oil and water phases, offering excellent structural characteristics that can address both effectively.
The preparation of the lamellar structured emulsion involves combining several ingredients, which are divided into two phases: Phase A and Phase B. The composition is detailed in Table 1.
3. A Clinical Study
A study was conducted a survey was conducted on 21 adult men and women aged 19 years or older with dry skin on the forearm area (the part from the elbow to the wrist). Patients are informed before participating in the study, and after receiving their consent, the study proceeds and is tracked through the adherence diary. Participants were instructed to apply the prepared emulsion twice daily (morning and evening). All measurements and evaluations were conducted in an environment with controlled temperature and humidity conditions (22±2℃, 50±5%), ensuring no air movement or direct sunlight exposure. For the study, the test area was cleansed during the visit, and participants were asked to wait for at least 30 minutes to allow the skin to stabilize [IRB:HE-R24-0083].
1) Evaluation of Skin Surface Moisture Improvement
Skin surface moisture content (A.U.) and average dielectric constant (ε) of the forearm area were measured before the application, after 2 weeks of use, and after 4 weeks of use to evaluate the improvement in skin surface moisture. The measurements for skin surface moisture improvement were conducted using a Corneometer CM825 Probe (Courage Khazaka GmbH, Germany) and Epsilon E100 (Biox Systems Ltd., England).
2) Evaluation of TEWL Improvement
The TEWL of the forearm area (g/m2h) was measured before the application, after 2 weeks of use, and after 4 weeks of use to evaluate the improvement in TEWL. The TEWL measurements were conducted using a Tewameter® TM 300 (Courage Khazaka electronic GmbH).
3) Evaluation of Itch Improvement
The itch scores of the forearm area were measured before the application, after 2 weeks of use, and after 4 weeks of use to evaluate the improvement in itching. The itch improvement was evaluated using the visual analog scale (VAS) assessment method (10-point scale) as shown in Table 2.
4) Evaluation of Adverse Skin Reactions
During the study period, the examiner monitored the occurrence of adverse skin reactions and the use of concomitant medications that could potentially affect the study outcomes. In the event of any adverse reaction, the examiner promptly notified the principal investigator. Upon verification, the principal investigator took appropriate measures and determined whether the participant could continue with the study.
5) Data Analysis and Interpretation
Statistical analysis was conducted using SPSS Statistics 26 to verify the statistical significance of changes before and after the use of the test product. Significance was confirmed at a 95% confidence interval with a p-value of <0.05. Continuous variables derived from device evaluations were expressed as means and standard deviations, while categorical variables from survey evaluations were expressed as frequencies and percentages. Normality of the data was assessed using the Shapiro-Wilk test. If normality was confirmed, parametric methods such as Repeated Measures ANOVA were used, followed by Bonferroni correction for post hoc analysis. In cases where normality was not satisfied, non-parametric methods such as the Friedman test were used, followed by Bonferroni correction and post hoc analysis with the Wilcoxon signed-rank test.
Results
1. Effect of Improving Skin Moisture
The skin surface moisture content (A.U.) of the forearm area significantly increased after 2 weeks and 4 weeks of using the test product compared to the baseline (Table 3). The initial average moisture content was 24.11±3.10 A.U., which increased to 31.71±2.78 A.U. after 2 weeks and 37.27±2.53 A.U. after 4 weeks. The statistical significance was confirmed with p-values of <0.001 for both time points. This indicates a substantial improvement in skin moisture, with improvement rates of 32.48% and 54.58% at 2 and 4 weeks, respectively, compared to the baseline.
The average dielectric constant (ε) of the forearm area showed a significant increase after 2 weeks and 4 weeks of using the test product compared to the baseline measurements (Table 4). Initially, the average dielectric constant was recorded at 5.61± 2.18. After 2 weeks of application, it increased to 16.38±2.56, and after 4 weeks, it further rose to 21.46±2.63. The statistical significance of these changes was confirmed with p-values of <0.001 for both time points, indicating that the product effectively improved the dielectric properties of the skin, which correlates with enhanced moisture content.
2. Effect of Reducing TEWL
The TEWL in the forearm area significantly decreased after 2 and 4 weeks of using the test product compared to baseline levels (Table 5). The baseline TEWL was 11.02±1.77 g/m2h, which decreased to 9.49±1.43 g/m2h after 2 weeks and further to 8.19 ±1.13 g/m2h after 4 weeks. Both reductions were statistically significant with p-values of <0.001. These results demonstrate that the product effectively reduced water loss from the skin, showing improvement rates of 13.88% and 25.68% at 2 and 4 weeks, respectively, compared to baseline.
3. Effect of Alleviating Itch
This section highlights significant reductions in itch scores on a 10-point scale after 2 and 4 weeks of using the test product compared to baseline (Table 6). The baseline itch score was 6.86 ±0.91, which decreased to 4.90±0.83 after 2 weeks and 2.81± 1.12 after 4 weeks. These reductions were statistically significant with p-values of <0.001 for both time points. The improvement rates were 28.47% and 59.03% at 2 and 4 weeks, respectively, indicating a notable reduction in itch severity.
Discussion
Strengthening the skin barrier to solve a problem, During the research on substances that help to improve skin barrier and skin itching, it was confirmed that Scutellaria baicalensis supercritically extracted under certain conditions has useful activity for improving skin itching by containing circular liquid crystal lamellar structure, and this substance was developed. Therefore, the present invention has been developed to provide the above-mentioned benefits without side effects in humans (Lee & Park, 2015; Kim et al., 2022).
The present study aims to provide a cosmetic composition comprising Scutellaria baicalensis as an active ingredient that has excellent effects on strengthening the skin barrier and improving skin itching.
Lamellar structures, composed of phospholipids arranged in alternating layers of oil and water, are significant for their role in skin hydration and barrier function. These structures not only enhance the skin’s moisture content but also contribute to the stability and usability of skincare formulations. The effectiveness of lamellar emulsions in improving skin hydration has been demonstrated in various studies, indicating their potential for widespread application in dermatology (Egawa & Hirao, 2007).
Scutellaria baicalensis, a plant native to East Asia, is renowned for its anti-inflammatory, antioxidant, and antimicrobial properties. Its major active components include glycosides like baicalin and wogonoside, and their aglycones, baicalein and wogonin. These constituents have been extensively studied for their biological activities, which include significant benefits for skin health, such as reducing inflammation and protecting against oxidative (Chanchal et al., 2023).
The study investigated the efficacy of a lamellar structured emulsion containing Scutellaria baicalensis root extract in improving skin surface moisture, reducing TEWL, and alleviating itch. The study involved 21 adult participants who applied the emulsion twice daily for four weeks. Measurements of skin surface moisture, TEWL, and itch severity were taken at baseline, after two weeks, and after four weeks using standardized instruments and methods, ensuring reliable and reproducible results (Yan et al., 2024; Safta et al., 2024; Zhu et al., 2006).
The results demonstrated significant improvements in skin hydration, as evidenced by the increase in skin moisture content from 24.11 to 37.27 A.U. and the dielectric constant from 5.61 to 21.46 after four weeks of use (p<0.001). These findings are consistent with previous research that underscores the effectiveness of lamellar structures in enhancing skin moisturization. Additionally, the study showed a significant reduction in TEWL from 11.02 to 8.19 g/m2h, indicating an improved barrier function (p<0.001). This is particularly important as TEWL is a critical indicator of the integrity of the skin barrier. The reduction in itch severity from 6.86 to 2.81 (p<0.001) further supports the emulsion’s potential in managing conditions associated with dry and itchy skin, aligning with the known anti-inflammatory properties of Scutellaria baicalensis. This aligns with the known properties of baicalin, a major component of Scutellaria baicalensis, which inhibits pro-inflammatory cytokines such as IL-6 and TNF-α (Li et al., 2004; Yoon et al. 2013).
Furthermore, the study (Wang et al., 2022; Park et al., 2024) demonstrates the effectiveness of Scutellaria baicalensis extract in alleviating conditions associated with dry and itchy skin, supporting the findings of this study. Further research is recommended to explore long-term effects and broader applications in skincare formulations (Kasolang et al., 2020; Kim et al., 2022).
No adverse reactions were reported during the study, suggesting that the emulsion is well-tolerated and safe for regular use. This is an important consideration for any skincare product, particularly those intended for sensitive or compromised skin (Ruge et al., 2021).
Conclusions
The lamellar structured emulsion containing Scutellaria baicalensis root extract demonstrated significant improvements in skin hydration, reduced TEWL, and alleviated itch without causing any adverse skin reactions. These findings suggest that the emulsion can effectively enhance skin barrier function and address common dermatological concerns such as dryness and itchiness. The emulsion's ability to improve skin moisture and reduce TEWL highlights its potential as a valuable addition to skincare formulations aimed at enhancing skin health.
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