Efficacy of anti‐sebum moisturizing cream containing 2% l‐carnitine and 5% epigallocatechin gallate in seborrhea: A randomized clinical trial

Seborrhea leads to facial greasiness and unpleasant feeling. People with seborrhea also have trouble with selecting moisturizers. l‐Carnitine and epigallocatechin gallate (EGCG) are reported anti‐sebum properties. However, neither efficacy comparison nor the combination effect of the two topical anti‐sebum agents was studied. Moisturizing cream with these agents is supposed to provide skin with an optimal water–oil balance.


| INTRODUC TI ON
Seborrhea is a common aesthetic problem in adolescence and reproductive age.The facial skin becomes greasy, causing discomfort feeling, acne, poor self-confidence, and socialization. 1 In addition, people with seborrhea have difficulty choosing skin care products, in particular a moisturizer, since conventional moisturizing cream has a tendency to be greasier and not allow for continuous application.In fact, moisturizer is necessary to maintain healthy skin condition.It also prevents the skin irritation or sensitization frequently causes by some therapeutic agents of acne treatment. 2A moisturizer with an anti-sebum agent will reduce sebum on the face and increases the water content of the skin.Therefore, it is supposed to be helpful to the oily skin people for better skin condition and perception.
At present, there is no standard topical treatment for reducing sebum on the face.However, there are several active ingredients that have been studied for the possession of sebum reduction properties. 3,4One of them is l-carnitine, a natural protein found in the human body that facilitates lipid transportation into the mitochondria of the sebocytes.It presents a concentration-dependent rise in beta-oxidation which is resulting in a deteriorating level of intracellular lipid content in sebocytes. 5Another substance is epigallocatechin gallate (EGCG), the active ingredients in green tea.It is one of the major polyphenol derivatives that has properties of a concentrationdependent inhibiting lipogenesis of the sebocytes, and also inducing apoptosis of human sebocytes. 6Additionally, it has a mechanism of antioxidant effect, anti-inflammatory effect, anti-androgenic effect, and antimicrobial effect against Cutibacterium acne. 6-8However, there have not been studies comparing the sebum-reducing effect between the two anti-sebum agents and the synergistic effect of the two mixtures.
Moisturizing cream contain humectants that attract water from the dermis to the epidermis together with occlusives that form hydrophobic film within the superficial interstitium between corneocytes to reduce transepidermal water loss (TEWL).Moisturizing cream for oily skin should be non-comedogenicity. 2Glycerin is an effective humectant that work well for oily-skinned people. 9The appropriate occlusive for oily skin is dimethicone, a silicone derivative, that does not cause greasy feeling after applying unlike other occlusive agents. 9,10In addition to improving the quality of the skin, moisturizer also promotes absorption of substances applied to the skin. 11e aim of this study was to evaluate and compare the efficacy of the anti-sebum moisturizers which using l-carnitine, EGCG, and the combination of both agents as the sebum-reducing agents together with glycerin and dimethicone as moisturizing cream base in order to determine an effective and safe topical treatment for seborrhea in the future.

| Study participant
Ninety subjects aged 18-40 years with oily skin type or combined skin type enrolled in the study were screened with modified criteria from Baumann et al. 12 The subjects were evaluated as follows: (1) characterization of their skin as oily skin type or combined skin type, (2) frequent perception of oily on the forehead and nose, (3) the face had been shiny and reflective after 2-3 h of face washing without applying any products, (4) face washing more than twice a day, and (5)   have comedones on the face.The exclusion criteria were subjects' pregnancy, lactation, history of allergic contact dermatitis, moderate or severe acne vulgaris, hyperandrogenism, subjects who have taken isotretinoin, spironolactone, anti-androgens, contraceptive pills within the past 6 months or have used a topical retinoid or oily skin products within the past 2 weeks, subjects who have received botulinum toxin or facial phototherapy within the past 6 months.

| Material
Three types of cream were used in the study: 2% l-carnitine cream, 5% EGCG cream, and a combination of 2% l-carnitine and 5% EGCG cream.The moisturizing cream formulation consists of dimethicone and glycerin which are present in equal amounts in all three creams.
Prior to the trial, all creams were subjected to an irritation test with a closed patch test.

| Treatment protocol
Subjects were randomly allocated to three treatment groups based on the type of cream.Subjects would not know what cream they received and were assigned to apply the cream all over the face twice a day, morning and evening after washing their face for 4 weeks.
During the study, subjects were given a gentle cleansing gel for washing their faces and refrained from using all other personal products, including sunscreen and makeup.

| Clinical assessment
Clinical assessment was conducted at baseline (Week 0), Weeks 1, 2, and 4. When subjects arrived at the research site, they had to wash their faces with the provided facial cleanser, then waited in a closed room with a temperature of 25°C and relative humidity at 50%-60% for 30 min.The subject's skins were then examined.The sebum level was measured with Sebumeter® SM815 (Courage + Khazaka) on the nose tip and forehead on both sides. 13,14e anti-sebum efficacy was evaluated by using the following formula: where, SebumT0 = Sebum level at baseline visit; SebumTx = Sebum level at each follow visit.
Achievement of oil control was defined by a mean sebum level below 106 μg/cm 2 after treatment. 15The median time to oil control from baseline was also evaluated.
Besides, skin capacitance and transepidermal water loss on both cheeks were measured with Corneometer® CM825 (Courage + Khazaka) and Tewameter® TM300 (Courage + Khazaka), respectively. 16,17Side effects of treatment were evaluated by both the physician and the subjects.All measurements were performed by the same observer.

| Subjective outcome evaluation
Oily skin perception and its effects on the subjects' psychological, sociability, and quality of life were assessed by the Oily skin selfimage questionnaire (OSSIQ) adapted from Segot-Chicq et al. 18 There were 18 questions about the oily skin towards the perception of the subjects.The total score obtained was a percentage calculated from the total score.High percentage scores mean that oily skin problems are very disturbing to the patient's perception.Subjects had to do a pretreatment and at Week 4 test to assess whether the subjects' sensitivity to oily skin improved after treatment.

| Statistical analyses
All statistical analyses were performed by STATA version17.The quantitative data were presented as mean and standard deviations.Mixed linear model was used to compare the differences between baseline and each time-point after treatment in each group and to compare the differences between the three groups.The categorical data were presented as numbers and percentages using the chisquare test to compare the differences between the three groups.
The Kaplan-Meier method was used to estimate the median time of oil control achievement in three groups, and Log-rank test was used for comparison between the groups.A p-value of less than 0.05 was considered statistically significant.

| RE SULTS
A total of 90 subjects participated and completed the study.
The subjects were 58 females and 32 males with a mean age of 27.62 years and were randomly divided into three groups of 30 each.
The baseline characteristic of the three groups was not different in demographic data, sebum level, skin capacitance, TEWL, and OSSIQ scores (Table 1).The baseline mean sebum levels for the l-carnitine group, the EGCG group, and the combine group were 155.50 ± 33.36, 141.15 ± 43.77, and 155.46 ± 34.25 μg/cm 2 , respectively, which were not significantly different (p = 0.279).

| Sebum level
The mean sebum levels of all three subjects were significantly lower from pretreatment (p < 0.01).The mean sebum level at Week 4 for the lcarnitine group was 99.66 ± 31.26, the EGCG group was 80.63 ± 29.55 and the combine group was 86.93 ± 24.70.When calculating the percentage reduction from baseline for anti-sebum efficacy, it was found that the value of the l-carnitine group was 34.84 ± 15.93%, the EGCG group was 41.36 ± 17.59% and the combine group was 43.45 ± 13.66% (Figure 1).When compared between the groups, it was found that the efficacy of combine group had statistically significantly higher antisebum efficacy than the l-carnitine group (p = 0.009).
According to the achievement of oil control, the number of subjects who achieved sebum control results on Day 28 from the l-carnitine, EGCG and combine groups were 14, 19, and 23, respectively.The l-carnitine group had a median time to oil control of 28 days.EGCG and the combine group had a median time to oil control of 14 days (Figure 2).When compared between the three groups, there was a statistically significant difference (p = 0.015).
There was no statistically significant difference between the EGCG group and the combine group (p = 0.069).

F I G U R E 2 Kaplan-Meier curves
for survival analysis of oil control achievement by different treatment (*p < 0.05).EGCG, epigallocatechin gallate.

| Subjective oiliness and life quality
The perception of oily skin and the psychological and social effects of the subjects assessed by the OSSIQ score found that all three groups had a statistically significant reduction in score, or perception compared to pretreatment.The l-carnitine group score decreased from 51.99 ± 20.65% at baseline to 25.13 ± 20.88% at Week 4 (p < 0.05; Table 1), the EGCG group score decreased from 43.

| Adverse effect
Subjects in three groups could continue to apply the cream throughout the period of study and revealed mild skin redness in one subject in the EGCG group and one subject in the combine group, which could be resolved at subsequent follow-ups without discontinuation of the cream.There was no itching or burning symptoms.The adverse effects between the three groups were not significantly different.

| DISCUSS ION
According to the study by Tangkijngamvong et al., 15 it was demonstrated that a sebum level greater than 106 μg/cm 2 was clearly as- glands.Combination of these could theoretically promote synergistic anti-sebum effect.When comparing the anti-sebum efficacy between the two formulations, it was found that the combine cream was statistically significantly lower in sebum levels than l-carnitine cream.A comparison between the EGCG group and the combine group in percentage of sebum reduction, including oil control achievement, are no statistically significant differences.In other words, l-carnitine may not significantly enhance EGCG's ability to reduce sebum level.However, if there is an extension of the sample size or the study period, it may make the difference more noticeable.
The efficacy of topical green tea in inhibiting skin sebum was studied by Mahmood et al., 19 which was a randomized controlled study in 22 subjects.In a study of 5% green tea emulsion versus 2.5% green tea plus 2.5% lotus emulsion once a day, it was found that at Week 4, sebum levels were reduced by 29.14% and 18.27%, respectively.
Another study by Meetham et al., 20 a randomized controlled study of 20 oily-skinned subjects using 4.5% green tea toner versus 7% green tea applied to their face once a day, found that at Week 4, sebum levels were reduced by 20.26% and 31.57%,respectively.Comparing to the results of the previous studies, EGCG cream and combine cream in our study had greater effect on sebum reduction.It may be caused by the effects of the following factors: (1) The green tea compound contains several polyphenol compounds with approximately 40%-60% EGCG. 21In fact, EGCG is the most potent polyphenol derivative along with the anti-androgen activity which cannot be found in some derivatives. 7,21From previous both in vitro and in vivo studies, it was found that the concentration of green tea or EGCG potentially tended to affect its anti-sebum efficacy. 6,20(2) The formulation of the topical drug as a moisturizing cream which nourishes the skin hydration can promote better absorption of the anti-sebum agent, resulting in a better therapeutic effect.(3) Applying an anti-sebum twice a day results in greater effects than applying once a day.This study found that applying twice daily did not cause serious side effects.
Concerning the effects on skin barrier, there was a study demonstrated that the TEWL in oily skin people was slightly higher than that of normal skin people. 22Some people with oily skin also had sensitive skin. 23Since there are the alteration and imbalance in lipid composition of sebum on the skin.The unsaturated free fatty acids, which are released from sebum by bacterial lipases, are demonstrated the inductions of calcium influx into epidermal keratinocytes and cause the abnormal epidermal keratinization process that can disrupt the barrier function. 23,24Our study demonstrated that the skin hydration was increased, while the TEWL were decreased after treatment.These determined the improvement of the waterreserving function of the skin.The moisturizers are supposed to provide hydration along with occlusive effects for restoration of the disrupted epidermal barrier.The overall results showed that when the facial oiliness was diminished, the skin hydration raised; the skin barrier function was promoted.
However, this study had some limitations.First, the study period may be extended to be sufficient to show how the most effective each anti-sebum agent is, and if treatment is discontinued, how long will the sebum control last.Second, this study did not have a placebo group to show that the reduction of sebum was due to the actual anti-sebum activity, not caused by other components of the cream formulation.

| CON CLUS IONS
In conclusion, anti-sebum moisturizing cream is beneficial and safe

ACK N OWLED G M ENTS
The researchers would like to thank the Faculty of Medicine, Srinakharinwirot University for providing the research funding.In addition, we sincerely thank all volunteers in this study.

CO N FLI C T O F I NTER E S T S TATEM ENT
The researchers declare no conflict of interest.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available from the corresponding author upon reasonable request.

E TH I C S S TATEM ENT
The

A
prospective, randomized, single-blinded clinical study was conducted at Skin Center Srinakharinwirot University, Bangkok, Thailand from November 2021 to March 2022.This study was endorsed by the Human Research Ethics Committee of Srinakharinwirot University.All subjects who participated in the study signed an informed consent form.
sociated with skin discomfort.Therefore, we used this cutoff value to indicate an effective clinical outcome for the anti-sebum action of the three moisturizing creams.It was found that all three anti-sebum creams were effective in reducing the level of sebum on the skin significantly and continuously decreasing with the length of time the cream was applied.Although the mean levels of sebum levels of the three treatment groups were similarly reduced through this criterion, it revealed that after treatment of the three groups, there were significant differences in numbers of people who achieved results and duration of the time to achieve the results.The EGCG group and the combine group had greater number of subjects who achieved oil control with shorter median time to oil control than l-carnitine group.The posttreatment sebum level reduction of the three group was consistent with the emotional, psychological, and social outcomes assessed by the OSSIQ score with significantly improved across all three groups.Mechanism of action of l-carnitine is facilitating the lipid catabolism while EGCG is inhibiting the lipogenetic process in sebaceous F I G U R E 3 Changes in the mean skin capacitance after treatment in the three groups.**p < 0.01.EGCG, epigallocatechin gallate.F I G U R E 4 Changes in the mean transepidermal water loss level after treatment in the three groups.*p < 0.05; **p < 0.01.EGCG, epigallocatechin gallate.
to reduce sebum on the skin, moisturize the skin and promote the epidermal barrier.Anti-sebum moisturizing cream has a positive effect on perception, satisfaction, and better skin quality.Anti-sebum compounds containing 2% l-carnitine combined with 5% EGCG, or 5% EGCG alone are more effective in sebum control than l-carnitine.5%EGCG alone can be substitute used to reduce the cost of treatment.In addition, EGCG possesses various bioactivities, including anti-inflammatory effect and antimicrobial effects on C. acne which can correct other key pathogenesis of acne.Therefore, it could be applied in further studies as adjuvant therapy and prevention of the side effects of acne treatment.AUTH O R CO NTR I B UTI O N SPD (MSc student) contributed to conceptualization, study design, data collection, and original draft preparation.NK contributed to conceptualization and all data analysis.AP contributed to the study material invention and study design.PU contributed to study planning, subject enrollment, and drafting the manuscript.MU contributed to critical review of study design, methodology, manuscript analysis, and final manuscript writing.All the authors have read and approved the final manuscript.