The Anti-Acne and Reduction of Hyperpigmentation Effects of Products Containing Retinol, Niacinamide, Ceramides, and Dipotassium Glycyrrhizinate in Chinese Women

Abstract

Acne vulgaris is a dermatological condition characterized by the hyperkeratinization of sebaceous follicles, which can further lead to post-inflammatory hyperpigmentation. Considering the intricate pathophysiology of acne, it is essential to develop novel topical therapies that are capable of targeting multiple underlying mechanisms of acne. The objective of this study was to study the effect of products containing retinol, niacinamide, ceramides, and dipotassium glycyrriszinate on acne-related markers. A total of 43 women with acne skin (including sensitive skin) were enrolled. To evaluate the effect of test products on acne-related indicators following 4 weeks of use, this study combined clinical assessments of skin condition (acne lesion counts), instrumental assessments (skin gloss), and photo tracking using VISIA-CR and Primos CR systems, which encompass metrics such as a*, ITA°, skin area (%) covered by sebum spots, and the presence of sebum spots. Adverse reactions were also assessed. After 4 weeks of treatment, significant reductions were observed in both the inflammatory acne lesion count and non-inflammatory acne lesion count, while there was also a significant decrease in skin redness a* and skin area (%) covered by sebum spots and a significant increase in skin brightness ITA° and gloss. No adverse events occurred during the entire testing process. In summary, the daily application of products containing retinol, niacinamide, and ceramides not only improves acne-related symptoms but also alleviates post-inflammatory hyperpigmentation caused by acne, which suggests that such products have the potential to meet the dual needs of brightening and acne care.

1. Introduction

Acne vulgaris (commonly referred to as acne) is a multifactorial dermatological condition characterized by a chronic course marked by recurrent acute flares and remissions, which imposes substantial social, psychological, and physical burdens on affected individuals [1,2]. Acne is a chronic inflammatory skin disease primarily affecting the hair follicle–sebaceous gland unit, commonly occurring during adolescence and predominantly on the face [3]. Globally, Acne vulgaris accounted for 4.96 million (95% uncertainty interval: 2.98–7.85) disability-adjusted life years (DALYs) in 2019 [4]. The prevalence rate of acne in the Chinese population is reported to be 8.1% [5]. Acne is a multifactorial condition characterized by various underlying factors. It typically involves excessive sebum production and enlargement of the sebaceous glands, which would lead to the formation of microcomedones. This process triggers inflammatory responses in keratinocytes and sebocytes, thereby attracting inflammatory cells. Notably, Cutibacterium acnes (C. acnes), an anaerobic bacterium commonly found in sebum-rich skin, is believed to play a role in perpetuating the pathogenic process of acne. C. acnes induces the production of proinflammatory and chemotactic molecules, further contributing to inflammation. The inflammatory processes involved in acne stimulate an overproduction of melanin and abnormal deposition, resulting in pigmentation issues known as post-inflammatory hyperpigmentation (PIH). These pigmentary sequelae can occur in individuals with all skin tones [6]. In addition, individuals with acne often experience negative emotions like embarrassment, humiliation, and self-consciousness, as well as lower self-esteem, anxiety, and depression [7].

The majority of conventional therapeutic agents used for treating acne and acne-related PIH are primarily designed to target a single pathophysiological aspect [8]. However, the underlying physiological and mechanistic dysregulations involved in acne and PIH development implicate multiple signaling pathways [9,10]. Consequently, it becomes apparent that a multi-targeted approach is necessary to effectively address this skin disorder. Increasing evidence emphasizes the significance of topical products that can simultaneously target multiple pathogenic factors [11]. By leveraging their complementary mechanisms of action, combination products offer a promising avenue for a comprehensive and multitargeted treatment approach to acne. Retinoids function by normalizing the process of desquamation through a reduction in keratinocyte proliferation and the promotion of differentiation [12]. Clinical studies have demonstrated that 0.2% retinol exhibits significant efficacy in ameliorating Acne vulgaris symptoms [13]. Niacinamide and ceramides exhibit strong anti-inflammatory effects and aids in the repair of the skin barrier [14,15]. Furthermore, research demonstrates that 4% niacinamide effectively addresses inflammatory Acne vulgaris in clinical trials [16]. Here, the objective of this study was to study the effect of products containing retinol, niacinamide, and ceramides on acne-related indicators.

2. Materials and Methods

This study was conducted in a group of 43 Chinese women with mean age 25.0 years. Volunteers were recruited through advertising and electronic media. And there are 22 people who self-reported sensitive skin in panels.

Exclusion criteria were as follows: history of allergy to facial care products; currently pregnant, or planning to become pregnant; suffering from heart, brain, lung, liver, or kidney diseases; subjects with cysts/nodules; subjects with occupational acne caused by chemicals; subjects with acne lesions caused by drugs; having a history of skin cancer within the past 5 years; psychological or mental diseases; having a health condition and/or pre-existing or dormant dermatologic disease on the face (e.g., psoriasis, rosacea, eczema, seborrheic dermatitis, severe excoriations) that the Investigator or designee deems inappropriate for participation or could interfere with the outcome of this study; active status of Herpes Simplex; regularly taking or have taken oral or topical prescription medications for acne such as doxycycline, minocycline, clindamycin, Bactrim, tetracycline, erythromycin, vibramycin, azelaic acid, and benzoyl; having observable sunburn, suntan, scars, nevi, excessive hair, unremovable facial jewelry, artificial eyelashes, eyelash extensions, or other conditions on the face that might influence the test results in the opinion of the Investigator or designee; currently using or having regularly used corticosteroids (systemic or topical, not nasal or ocular) within the past 4 weeks (including but not limited to betamethasone, clobetasol, desoximetasone, diflorasone, fluocinonide, fluticasone, mometasone, halcinonide, and halobetasol); has participated in any clinical trial during the study period; having started hormone replacement therapy (HRT) or hormones for birth control less than 3 months prior to study entry or who plan on starting, stopping, or changing doses of HRT or hormones for birth control during this study; having a history of immunosuppression/immune deficiency disorders (including HIV infection, AIDS, multiple sclerosis, Crohn’s disease, rheumatoid arthritis), organ transplant (heart, kidney, etc.), or currently using oral or systemic immunosuppressive medications and biologics; and having a disease such as asthma, diabetes, epilepsy, hypertension, hyperthyroidism, or hypothyroidism that is not controlled by diet or medication. Individuals having multiple health conditions may be excluded from participation even if the conditions are controlled by diet, medication, etc.; other exclusion criteria include routinely having excess exposure to sun via outdoor activities (e.g., sunbathing) and having any planned surgeries or invasive medical procedures during this study; Non-invasive medical procedures or surgeries were reviewed for their impact on the study outcome and acceptability by the Investigator or designee; additional exclusion criteria include the following: subject having applied self-tanner products on the concerned areas during the 4 weeks before the starting day of this study; subject having undergone aesthetic care at home or in a beauty salon (such as exfoliating scrub, mask, deep cleansing) on the evaluation areas during the 2 weeks before the starting day of this study. Inclusion criteria were as follows: Chinese female, 18 to 60 years of age; in good general health (physical, mental, and social well-being, not merely the absence of disease/infirmity), according to subject self-report; all types of skin, 50% of subjects self-perceived sensitive skin; subjects self-perceived acne prone skin; have not used any acne products or received any treatment for acne in the past 1 or 2 weeks; daily use of sunscreen with SPF 15 or higher; willing to provide written informed consent and able to read, speak, write, and understand Mandarin; willing to cooperate and participate by following study requirements for the duration of this study and to report any changes in health status or medications, AE symptoms, or reactions immediately; having not had any facial treatments in the past 6 months and are willing to withhold all facial treatments during the course of this study including facials, facial peels, photo facials, laser treatments, dermabrasion, botulinum toxin (Botox^®), injectable filler treatments, intense pulsed light (IPL), acid treatments, tightening treatments, facial plastic surgery, or any other treatment administered by a physician or skin care professional designed to improve the appearance or firmness of facial skin; with at least 10 open comedones caused by clogged pores on the nose at baseline visit; having 3 or more inflammatory acne lesions (papules, pustules) and 5 or more non-inflammatory acne lesions (open and closed comedones) on the global face at baseline visit; with at least 1 targeted pigmentation that is mild to moderate (score of 3–6 according to a modified Griffiths scale 1). This targeted pigmentation’s diameter should be ≥2 mm with sharp contrast at the edge. The treatment products contains 0.06% retinol, 2% niacinamide, 1% dipotassium glycyrrhizinate, and, more importantly, ceramide 1,3,6-II (ceramide EOP, ceramide NP, ceramide AP).

All subjects were informed and gave their consent before enrollment. This study was conducted by SGS-CSTC Standards Technical Services Co., Ltd. Xiamen Branch. The code of SGS ethics committee for clinical research is No. 2023021, and test reference is no.: SHCPCHE23000048.

2.1. Clinical Assessment

Clinical assessment of acne lesion at baseline, weeks 2 and 4, includes counting inflammatory lesions and non-inflammatory lesions. The total number of lesions is the sum of inflammatory and non-inflammatory lesions. Inflammatory lesions are defined as the combination of papules and pustules, while non-inflammatory lesions comprise open comedones (blackheads) and closed comedones (whiteheads).

2.2. Photo Tracking

2.2.1. VISIA-CR Imaging Procedures

VISIA-CR imaging procedures were performed at baseline, weeks 2 and 4. Prior to imaging procedures, clinic personnel ensured that subjects had a clean face with no makeup. Subjects removed any jewelry from the areas to be photographed. Clinic personnel provided subjects with a black matte headband to keep hair away from the face, and a black matte cloth was draped over the subjects’ clothing. Subjects were instructed to adopt neutral, nonsmiling expressing with their eyes gently closed and were carefully positioned for each photograph. Digital images were taken of each subject’s face (left, center, and right views) using the VISIA-CR photo station (Canfield Imaging Systems, Fairfield, NJ, USA) with a Canon Mark II digital SLR camera (Canon Incorporated, Tokyo, Japan).

The IPP 7.0.1.658 software was used to analyze the a* and ITA value according to a predetermined randomization list in every subject’s RBX-Red lighting mode images taken by VISIA CR. The analysis area should remain the same for each subject’s images at each time point. The index a* directly reflects the situation of blood hemoglobin in the dermal papillary layer, while the ITA measures the brightness of facial skin. The IPP software was also be used to analyze the number of open comedones on the nose in every subject’s images taken by VISIA CR. In addition, the IPP software was used to analyze the targeted pigmentation area, proportion of the targeted pigmentation area, and targeted pigmentation’s optical density in the AOI area.

2.2.2. Visioscan^® VC 20plus and Sebufix^® F 16 Imaging Procedures

Visioscan^® VC 20plus and Sebufix^® F 16 imaging procedures were performed at baseline, weeks 2 and 4. Visioscan^® VC 20plus and Sebufix^®F 16 imaging procedures were taken on the area where oil secretion was most vigorous on the forehead. Visioscan^® VC 20plus (Courage + Khazaka electronic GmbH, Köln, Germany) is a UVA-light (390–395 nm) video camera with high resolution to study the skin surface directly. The image captures skin surface texture, which can be characterized using Surface Evaluation of the Living Skin (SELS) parameters. The imaging area is 10 mm × 8 mm at a resolution of 1280 × 1024 pixels. Sebufix^®F 16 (Courage + Khazaka electronic GmbH, Köln, Germany) analyzes the sebum content of the skin not only quantitatively but also qualitatively (how quick and how constantly the sebum production takes place). The parameters “skin area (%) covered by sebum spots”, reflecting the sebum content, were calculated using Visioscan^® VC 20plus and Sebufix^® F 16 image on the forehead.

2.2.3. Primos CR Imaging Procedures

The Primos CR system is a 3D imaging device to assess the microtopography of skin. In this study, it was positioned for acne volume evaluation [17,18]. Primos CR imaging procedures were performed at baseline, weeks 2 and 4. The targeted raised inflammatory lesion was captured, and subsequent analysis of volume was conducted through Primos 5.8E software.

2.3. Bioinstrumentation Measurements

Skin-Glossymeter GL 200 (Courage + Khazaka electronic GmbH (CK), Köln Germany) was performed at baseline, weeks 2 and 4. Skin gloss is the attribute that describes the way the skin’s surface reflects light. The probe measures reflection. The gloss of a surface can be expressed by direct reflection of light send to this surface. In the probe head, parallel white light was sent in a 60 degree angle to the skin surface. Part of the light was directly reflected in the same angle (angle of incidence = angle of reflection), and part of the light was absorbed by the surface and then scattered and reflected. The Skin-Glossymeter GL 200 measures both the portion of directly reflected light (reflection channel), mirrored from the surface, which is related to the gloss and the scattered portion from the surface (diffuse channel).

2.4. Biostatistics and Data Management

The changes were calculated in each parameter after use by subtracting the post-use measurement from the pre-use measurement. The paired t-test or Wilcoxon signed-rank test was used to test the null hypothesis that the mean change value before use was zero. Statistical analysis was performed using SPSS 28.0 with a significance level of α = 0.05 and a two-tailed test.

3. Results

3.1. Clinical Assessment

The longitudinal assessment of acne lesion counts demonstrated progressive improvements across all lesion categories from baseline through week 4 of treatment. At the 2-week evaluation, inflammatory lesions showed marked reduction, with papules decreasing by 20.23% (p < 0.05) and total inflammatory lesions declining by 21.33% (p < 0.05). Although pustules demonstrated a substantial 28.95% reduction, this change did not reach statistical significance, potentially reflecting the variable nature of these acute inflammatory lesions. Non-inflammatory lesions exhibited even greater improvement at week 2, with open comedones showing a robust 39.62% reduction (p < 0.05) and closed comedones decreasing by 25.00% (p < 0.05). These changes contributed to a significant 25.93% reduction in total non-inflammatory lesions (p < 0.05). The combined improvement across all lesion types resulted in a 24.71% reduction in total lesion count (p < 0.05).

By week 4, the therapeutic effects showed further enhancement. Inflammatory lesions demonstrated progressive improvement, with papules decreasing by 29.01% (p < 0.05) and total inflammatory lesions declining by 30.33% (p < 0.05) compared to baseline. Pustules showed a more pronounced 39.47% reduction, though this change remained statistically non-significant. Among non-inflammatory lesions, open comedones maintained substantial improvement with a 41.51% reduction (p < 0.05), while closed comedones showed a 21.39% decrease (p < 0.05). The total non-inflammatory lesion count decreased by 22.68% (p < 0.05), and the overall lesion burden showed a 24.71% reduction (p < 0.05) compared to baseline (

Table 1. Clinical assessment of acne lesion counts.

Parameter	Mean			Rate of Change		Significant Difference Compared with D0
	Baseline	Week 2	Week 4	Week 2	Week 4	Week 2	Week 4
Papule count	6.09	4.86	4.33	−20.23%	−29.01%	0.035	0.001
Pustules count	0.88	0.63	0.53	−28.95%	−39.47%	0.27	0.198
Total inflammatory lesion count	6.98	5.49	4.86	−21.33%	−30.33%	0.015	<0.001
Open comedone count (on face)	1.23	0.74	0.72	−39.62%	−41.51%	0.018	0.016
Closed comedone count	18.05	13.53	14.19	−25.00%	−21.39%	<0.001	0.002
Total non-inflammatory lesion count	19.28	14.28	14.91	−25.93%	−22.68%	<0.001	0.001
Total lesion count	26.26	19.77	14.88	−18.73%	−23.17%	<0.001	<0.001

).

The differential response patterns observed between weeks 2 and 4 suggest distinct therapeutic trajectories for different lesion types. While inflammatory lesions showed progressive improvement throughout the treatment period, non-inflammatory lesions demonstrated more rapid initial response with some plateauing effects by week 4. These patterns may reflect the distinct pathophysiological mechanisms underlying different acne lesion types and their respective response kinetics to treatment intervention.

3.2. Image Analysis

The following will present several key indicators obtained through image analysis, including the number of skin comedones (nose), the volume of targeted raised inflammatory lesions, the percentage of skin area covered by sebum spots, a*, and ITA.

Skin Acne-Related Indicators

The clinical evaluation demonstrated significant improvements in comedonal lesions following treatment intervention. At the 2-week follow-up, quantitative analysis revealed a statistically significant reduction in nasal comedones by 21.06% compared to baseline measurements (p < 0.05). This improvement was clinically evident, with 86% of study participants showing measurable enhancement in their comedonal profile. The therapeutic effects became more pronounced by week 4, with a marked 25.76% reduction in nasal comedone count relative to baseline (p < 0.05). At this time point, an overwhelming majority of participants (98%) exhibited clinical improvement, as illustrated in Figure 1.

The therapeutic outcomes demonstrated significant reductions in inflammatory lesion volume throughout the treatment period. Comparative analysis against baseline measurements revealed a substantial 25.04% decrease in the volume of targeted raised inflammatory lesions at the 2-week evaluation point (p < 0.05). This early response was clinically meaningful, with 95% of participants showing measurable improvement. The anti-inflammatory effects continued to progress, reaching a 31.04% reduction in lesion volume by week 4 (p < 0.05), accompanied by an increased responder rate of 98%. As depicted in Figure 2, these findings indicate a progressive therapeutic response.

The quantitative assessment of sebum regulation revealed marked improvements in sebum spot distribution throughout the treatment period. At the 2-week evaluation, digital image analysis demonstrated a 46.73% reduction in the percentage of skin area covered by sebum spots compared to baseline measurements (p < 0.05 versus baseline), with all participants (100%) showing measurable improvement. The therapeutic effects on sebum regulation continued to progress, reaching a 63.44% decrease in sebum spot coverage by week 4 (p < 0.05 versus baseline), with 95% of participants maintaining improvement (Figure 3).

The evaluation of skin erythema, as measured by a* values, demonstrated significant improvements throughout the treatment period. At the 2-week assessment point, colorimetric analysis revealed a 9.57% reduction in a* values compared to baseline measurements (p < 0.05), indicating a measurable decrease in cutaneous redness. This improvement was clinically relevant, with 88% of participants showing positive changes in erythema parameters. The therapeutic effects on skin redness showed continued progression, with a 10.31% reduction in a* values observed at week 4 compared to baseline (p < 0.05). While the absolute reduction in a* values increased between weeks 2 and 4, the responder rate remained stable at 88%, suggesting consistent treatment efficacy across the study population (Figure 4).

The assessment of skin tone improvement, quantified through ITA° values, demonstrated significant enhancements in skin brightness throughout the treatment period. At the 2-week evaluation, analysis revealed a 21.20% increase in ITA° values compared to baseline measurements (p < 0.05), indicating measurable improvement in skin tone luminosity (Figure 5). This improvement was clinically significant, with 93% of participants showing positive changes in skin brightness parameters. The skin tone enhancement continued to progress, reaching a 24.77% increase in ITA° values by week 4 compared to baseline (p < 0.05).

3.3. Bioinstrumentation Measurements

The evaluation of cutaneous surface characteristics demonstrated significant improvements in skin gloss throughout the treatment period. At the 2-week assessment, photometric analysis revealed an 8.02% increase in skin gloss compared to baseline measurements (p < 0.05), indicating measurable enhancement in skin surface reflectivity. This improvement was nearly universal, with 98% of participants showing positive changes in skin gloss parameters. The treatment effects on skin surface quality showed progressive enhancement, reaching a 16.33% increase in skin gloss by week 4 compared to baseline (p < 0.05). Notably, the responder rate reached 100% at week 4, demonstrating complete treatment efficacy in improving skin gloss among the study population (Figure 6).

4. Discussion

Acne is a complex condition influenced by multiple factors. It commonly involves increased sebum production and enlargement of the sebaceous glands, resulting in the development of microcomedones caused by the excessive buildup of keratin in follicular walls [19]. Our research demonstrates that a product containing retinol, ceramides, niacinamide, and dipotassium glycyrrhizinate can effectively reduce the number of acne lesions and regulate sebum secretion. Retinoids function by normalizing the process of desquamation through a reduction in keratinocyte proliferation and the promotion of differentiation. Niacinamide has the ability to regulate sebum production and also possesses anti-inflammatory properties [20,21]. Our study also demonstrates a significant reduction in both redness (a*) and volume of the targeted raised inflammatory lesion after using the products, suggesting that it not only prevents skin irritation but also possesses potential anti-inflammatory properties. In the past decade, a growing body of evidence has highlighted the involvement of inflammation in all stages of acne, including the subclinical phase that occurs before the formation of comedones [22]. Previous in vitro studies have indicated that ceramides not only possess skin barrier reparative properties but also exhibit the ability to downregulate the expression of inflammatory enzymes and cytokines, consequently exerting an anti-inflammatory effect [23]. Specifically, acne is linked to intrinsic impairments in epidermal barrier function [24], and recent studies have shown that acne-affected skin exhibits lower levels of ceramides, indicating the potential significance of ceramides in acne [25]. In addition, dipotassium glycyrrhizinate also exerts its anti-inflammatory effect by inhibiting the inflammatory cytokines IL-4 and IL-13 [26]. Topical retinoids exert their anti-inflammatory effects in acne through the modulation of key inflammatory mechanisms, including the inhibition of toll-like receptor signaling, the suppression of leukocyte chemotaxis, and the downregulation of the AP-1 transcriptional pathway [27].

Post-inflammatory hyperpigmentation (PIH) commonly accompanies acne and can be more concerning for patients than the acne lesions [28]. In cases of post-inflammatory hyperpigmentation (PIH) related to acne, current understanding suggests that arachidonic acid release triggered by epidermal inflammatory processes undergoes oxidation, generating prostaglandins, leukotrienes, and related compounds that activate melanocyte function [29]. This biochemical cascade results in increased melanin production and subsequent transfer to surrounding keratinocytes. The prevailing hypothesis indicates a direct relationship between the severity of the pigmentary reaction and both the intensity of inflammation and the duration or recurrent nature of the inflammatory response [30]. The results demonstrate that our product not only improves acne-related symptoms but also significantly enhances skin luminosity (ITA°). This is primarily due to the presence of retinol in the product, which inhibits tyrosinase expression [31]. Tyrosinase, the key regulatory enzyme, plays a central role in mediating melanogenesis, including the pigmentary processes associated with post-inflammatory hyperpigmentation in acne [32]. Tyrosinase serves as the critical enzyme responsible for the biosynthesis of both eumelanin, which confers black and brown pigmentation, and pheomelanin, which produces yellow to red hues. Additionally, niacinamide can also suppress melanosome transfer [31]. Melanocytes, located within the basal layer of the epidermis adjacent to the dermal–epidermal junction, establish functional connections with surrounding keratinocytes through dendritic processes, facilitating the transfer of melanin-containing melanosomes to provide photoprotection [33]. Furthermore, ceramides and dipotassium glycyrrhizinate exert anti-inflammatory effects.

Our study has several limitations. One area for improvement is to design in vitro experiments to explore the synergistic mechanisms of multiple ingredients in depth. In addition, we only focused on Chinese women subjects in this study. Future studies should expand participant demographics to include individuals across diverse ethnicities, skin types, and gender groups to enhance the generalizability and applicability of the research findings. Another limitation of our study is the lack of a control group. Future studies should establish a control group to exclude the effects of placebo and other external factors. The establishment of a control group will help to more accurately assess the true effects of the ingredients. Finally, the observation period for adverse events was only four weeks. Longer-term studies are needed to assess the long-term safety and efficacy of the product.

5. Conclusions

In summary, the daily application of products containing retinol, niacinamide, ceramides, and dipotassium glycyrrhizinate not only improves acne-related symptoms but also alleviates post-inflammatory hyperpigmentation caused by acne, which suggests that such products have the potential to meet the dual needs of brightening and acne care.